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XCCDF
Red Hat Enterprise Linux 9 Security Technical Implementation Guide
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An XCCDF Profile
Details
Items
Prose
452 rules organized in 452 groups
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must be a vendor-supported release.
High Severity
An operating system release is considered "supported" if the vendor continues to provide security patches for the product. With an unsupported release, it will not be possible to resolve security issues discovered in the system software. Red Hat offers the Extended Update Support (EUS) add-on to a Red Hat Enterprise Linux subscription, for a fee, for those customers who wish to standardize on a specific minor release for an extended period.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 vendor packaged system security patches and updates must be installed and up to date.
Medium Severity
Installing software updates is a fundamental mitigation against the exploitation of publicly known vulnerabilities. If the most recent security patches and updates are not installed, unauthorized users may take advantage of weaknesses in the unpatched software. The lack of prompt attention to patching could result in a system compromise.
SRG-OS-000023-GPOS-00006
1 Rule
RHEL 9 must display the Standard Mandatory DOD Notice and Consent Banner before granting local or remote access to the system via a command line user logon.
Medium Severity
Display of a standardized and approved use notification before granting access to the operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance. System use notifications are required only for access via login interfaces with human users and are not required when such human interfaces do not exist. Satisfies: SRG-OS-000023-GPOS-00006, SRG-OS-000228-GPOS-00088
SRG-OS-000480-GPOS-00227
1 Rule
The graphical display manager must not be the default target on RHEL 9 unless approved.
Medium Severity
Unnecessary service packages must not be installed to decrease the attack surface of the system. Graphical display managers have a long history of security vulnerabilities and must not be used, unless approved and documented.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must enable the hardware random number generator entropy gatherer service.
Low Severity
The most important characteristic of a random number generator is its randomness, namely its ability to deliver random numbers that are impossible to predict. Entropy in computer security is associated with the unpredictability of a source of randomness. The random source with high entropy tends to achieve a uniform distribution of random values. Random number generators are one of the most important building blocks of cryptosystems. The rngd service feeds random data from hardware device to kernel random device. Quality (nonpredictable) random number generation is important for several security functions (i.e., ciphers).
SRG-OS-000269-GPOS-00103
1 Rule
RHEL 9 systemd-journald service must be enabled.
Medium Severity
In the event of a system failure, RHEL 9 must preserve any information necessary to determine cause of failure and any information necessary to return to operations with least disruption to system processes.
SRG-OS-000324-GPOS-00125
1 Rule
The systemd Ctrl-Alt-Delete burst key sequence in RHEL 9 must be disabled.
High Severity
A locally logged-on user who presses Ctrl-Alt-Delete when at the console can reboot the system. If accidentally pressed, as could happen in the case of a mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot. In a graphical user environment, risk of unintentional reboot from the Ctrl-Alt-Delete sequence is reduced because the user will be prompted before any action is taken. Satisfies: SRG-OS-000324-GPOS-00125, SRG-OS-000480-GPOS-00227
SRG-OS-000324-GPOS-00125
1 Rule
The x86 Ctrl-Alt-Delete key sequence must be disabled on RHEL 9.
High Severity
A locally logged-on user who presses Ctrl-Alt-Delete when at the console can reboot the system. If accidentally pressed, as could happen in the case of a mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot. In a graphical user environment, risk of unintentional reboot from the Ctrl-Alt-Delete sequence is reduced because the user will be prompted before any action is taken. Satisfies: SRG-OS-000324-GPOS-00125, SRG-OS-000480-GPOS-00227
SRG-OS-000324-GPOS-00125
1 Rule
RHEL 9 debug-shell systemd service must be disabled.
Medium Severity
The debug-shell requires no authentication and provides root privileges to anyone who has physical access to the machine. While this feature is disabled by default, masking it adds an additional layer of assurance that it will not be enabled via a dependency in systemd. This also prevents attackers with physical access from trivially bypassing security on the machine through valid troubleshooting configurations and gaining root access when the system is rebooted. Satisfies: SRG-OS-000324-GPOS-00125, SRG-OS-000480-GPOS-00227
SRG-OS-000080-GPOS-00048
1 Rule
RHEL 9 must require a boot loader superuser password.
Medium Severity
To mitigate the risk of unauthorized access to sensitive information by entities that have been issued certificates by DOD-approved PKIs, all DOD systems (e.g., web servers and web portals) must be properly configured to incorporate access control methods that do not rely solely on the possession of a certificate for access. Successful authentication must not automatically give an entity access to an asset or security boundary. Authorization procedures and controls must be implemented to ensure each authenticated entity also has a validated and current authorization. Authorization is the process of determining whether an entity, once authenticated, is permitted to access a specific asset. Information systems use access control policies and enforcement mechanisms to implement this requirement. Password protection on the boot loader configuration ensures users with physical access cannot trivially alter important bootloader settings. These include which kernel to use, and whether to enter single-user mode.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must disable the ability of systemd to spawn an interactive boot process.
Medium Severity
Using interactive or recovery boot, the console user could disable auditing, firewalls, or other services, weakening system security.
SRG-OS-000080-GPOS-00048
1 Rule
RHEL 9 must require a unique superusers name upon booting into single-user and maintenance modes.
High Severity
Having a nondefault grub superuser username makes password-guessing attacks less effective.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /boot/grub2/grub.cfg file must be group-owned by root.
Medium Severity
The "root" group is a highly privileged group. Furthermore, the group-owner of this file should not have any access privileges anyway.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /boot/grub2/grub.cfg file must be owned by root.
Medium Severity
The " /boot/grub2/grub.cfg" file stores sensitive system configuration. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must disable virtual system calls.
Medium Severity
System calls are special routines in the Linux kernel, which userspace applications ask to do privileged tasks. Invoking a system call is an expensive operation because the processor must interrupt the currently executing task and switch context to kernel mode and then back to userspace after the system call completes. Virtual system calls map into user space a page that contains some variables and the implementation of some system calls. This allows the system calls to be executed in userspace to alleviate the context switching expense. Virtual system calls provide an opportunity of attack for a user who has control of the return instruction pointer. Disabling virtual system calls help to prevent return oriented programming (ROP) attacks via buffer overflows and overruns. If the system intends to run containers based on RHEL 6 components, then virtual system calls will need enabled so the components function properly. Satisfies: SRG-OS-000480-GPOS-00227, SRG-OS-000134-GPOS-00068
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must clear the page allocator to prevent use-after-free attacks.
Medium Severity
Poisoning writes an arbitrary value to freed pages, so any modification or reference to that page after being freed or before being initialized will be detected and prevented. This prevents many types of use-after-free vulnerabilities at little performance cost. Also prevents leak of data and detection of corrupted memory. Satisfies: SRG-OS-000480-GPOS-00227, SRG-OS-000134-GPOS-00068
SRG-OS-000433-GPOS-00192
1 Rule
RHEL 9 must clear SLUB/SLAB objects to prevent use-after-free attacks.
Medium Severity
Some adversaries launch attacks with the intent of executing code in nonexecutable regions of memory or in memory locations that are prohibited. Security safeguards employed to protect memory include, for example, data execution prevention and address space layout randomization. Data execution prevention safeguards can be either hardware-enforced or software-enforced with hardware providing the greater strength of mechanism. Poisoning writes an arbitrary value to freed pages, so any modification or reference to that page after being freed or before being initialized will be detected and prevented. This prevents many types of use-after-free vulnerabilities at little performance cost. Also prevents leak of data and detection of corrupted memory. SLAB objects are blocks of physically contiguous memory. SLUB is the unqueued SLAB allocator. Satisfies: SRG-OS-000433-GPOS-00192, SRG-OS-000134-GPOS-00068
SRG-OS-000433-GPOS-00193
1 Rule
RHEL 9 must enable mitigations against processor-based vulnerabilities.
Low Severity
Kernel page-table isolation is a kernel feature that mitigates the Meltdown security vulnerability and hardens the kernel against attempts to bypass kernel address space layout randomization (KASLR). Satisfies: SRG-OS-000433-GPOS-00193, SRG-OS-000095-GPOS-00049
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must enable auditing of processes that start prior to the audit daemon.
Low Severity
Without the capability to generate audit records, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. If auditing is enabled late in the startup process, the actions of some startup processes may not be audited. Some audit systems also maintain state information only available if auditing is enabled before a given process is created. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000473-GPOS-00218, SRG-OS-000254-GPOS-00095
SRG-OS-000132-GPOS-00067
1 Rule
RHEL 9 must restrict access to the kernel message buffer.
Medium Severity
Preventing unauthorized information transfers mitigates the risk of information, including encrypted representations of information, produced by the actions of prior users/roles (or the actions of processes acting on behalf of prior users/roles) from being available to any current users/roles (or current processes) that obtain access to shared system resources (e.g., registers, main memory, hard disks) after those resources have been released back to information systems. The control of information in shared resources is also commonly referred to as object reuse and residual information protection. This requirement generally applies to the design of an information technology product, but it can also apply to the configuration of particular information system components that are, or use, such products. This can be verified by acceptance/validation processes in DOD or other government agencies. There may be shared resources with configurable protections (e.g., files in storage) that may be assessed on specific information system components. Restricting access to the kernel message buffer limits access to only root. This prevents attackers from gaining additional system information as a nonprivileged user. Satisfies: SRG-OS-000132-GPOS-00067, SRG-OS-000138-GPOS-00069
SRG-OS-000132-GPOS-00067
1 Rule
RHEL 9 must prevent kernel profiling by nonprivileged users.
Medium Severity
Preventing unauthorized information transfers mitigates the risk of information, including encrypted representations of information, produced by the actions of prior users/roles (or the actions of processes acting on behalf of prior users/roles) from being available to any current users/roles (or current processes) that obtain access to shared system resources (e.g., registers, main memory, hard disks) after those resources have been released back to information systems. The control of information in shared resources is also commonly referred to as object reuse and residual information protection. This requirement generally applies to the design of an information technology product, but it can also apply to the configuration of particular information system components that are, or use, such products. This can be verified by acceptance/validation processes in DOD or other government agencies. There may be shared resources with configurable protections (e.g., files in storage) that may be assessed on specific information system components. Setting the kernel.perf_event_paranoid kernel parameter to "2" prevents attackers from gaining additional system information as a nonprivileged user. Satisfies: SRG-OS-000132-GPOS-00067, SRG-OS-000138-GPOS-00069
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent the loading of a new kernel for later execution.
Medium Severity
Changes to any software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor. Disabling kexec_load prevents an unsigned kernel image (that could be a windows kernel or modified vulnerable kernel) from being loaded. Kexec can be used subvert the entire secureboot process and should be avoided at all costs especially since it can load unsigned kernel images. Satisfies: SRG-OS-000480-GPOS-00227, SRG-OS-000366-GPOS-00153
SRG-OS-000132-GPOS-00067
1 Rule
RHEL 9 must restrict exposed kernel pointer addresses access.
Medium Severity
Exposing kernel pointers (through procfs or "seq_printf()") exposes kernel writeable structures, which may contain functions pointers. If a write vulnerability occurs in the kernel, allowing write access to any of this structure, the kernel can be compromised. This option disallows any program without the CAP_SYSLOG capability to get the addresses of kernel pointers by replacing them with "0". Satisfies: SRG-OS-000132-GPOS-00067, SRG-OS-000433-GPOS-00192, SRG-OS-000480-GPOS-00227
SRG-OS-000312-GPOS-00123
1 Rule
RHEL 9 must enable kernel parameters to enforce discretionary access control on hardlinks.
Medium Severity
By enabling the fs.protected_hardlinks kernel parameter, users can no longer create soft or hard links to files they do not own. Disallowing such hardlinks mitigates vulnerabilities based on insecure file system accessed by privileged programs, avoiding an exploitation vector exploiting unsafe use of open() or creat(). Satisfies: SRG-OS-000312-GPOS-00123, SRG-OS-000324-GPOS-00125
SRG-OS-000312-GPOS-00123
1 Rule
RHEL 9 must enable kernel parameters to enforce discretionary access control on symlinks.
Medium Severity
By enabling the fs.protected_symlinks kernel parameter, symbolic links are permitted to be followed only when outside a sticky world-writable directory, or when the user identifier (UID) of the link and follower match, or when the directory owner matches the symlink's owner. Disallowing such symlinks helps mitigate vulnerabilities based on insecure file system accessed by privileged programs, avoiding an exploitation vector exploiting unsafe use of open() or creat(). Satisfies: SRG-OS-000312-GPOS-00123, SRG-OS-000324-GPOS-00125
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must disable the kernel.core_pattern.
Medium Severity
A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers trying to debug problems.
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must be configured to disable the Asynchronous Transfer Mode kernel module.
Medium Severity
Disabling Asynchronous Transfer Mode (ATM) protects the system against exploitation of any flaws in its implementation.
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must be configured to disable the Controller Area Network kernel module.
Medium Severity
Disabling Controller Area Network (CAN) protects the system against exploitation of any flaws in its implementation.
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must be configured to disable the FireWire kernel module.
Medium Severity
Disabling firewire protects the system against exploitation of any flaws in its implementation.
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must disable the Stream Control Transmission Protocol (SCTP) kernel module.
Medium Severity
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Failing to disconnect unused protocols can result in a system compromise. The Stream Control Transmission Protocol (SCTP) is a transport layer protocol, designed to support the idea of message-oriented communication, with several streams of messages within one connection. Disabling SCTP protects the system against exploitation of any flaws in its implementation.
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must disable the Transparent Inter Process Communication (TIPC) kernel module.
Medium Severity
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Failing to disconnect unused protocols can result in a system compromise. The Transparent Inter Process Communication (TIPC) is a protocol that is specially designed for intra-cluster communication. It can be configured to transmit messages either on UDP or directly across Ethernet. Message delivery is sequence guaranteed, loss free and flow controlled. Disabling TIPC protects the system against exploitation of any flaws in its implementation.
SRG-OS-000433-GPOS-00193
1 Rule
RHEL 9 must implement address space layout randomization (ASLR) to protect its memory from unauthorized code execution.
Medium Severity
Address space layout randomization (ASLR) makes it more difficult for an attacker to predict the location of attack code they have introduced into a process' address space during an attempt at exploitation. Additionally, ASLR makes it more difficult for an attacker to know the location of existing code in order to repurpose it using return oriented programming (ROP) techniques. Satisfies: SRG-OS-000433-GPOS-00193, SRG-OS-000480-GPOS-00227
SRG-OS-000132-GPOS-00067
1 Rule
RHEL 9 must disable access to network bpf system call from nonprivileged processes.
Medium Severity
Loading and accessing the packet filters programs and maps using the bpf() system call has the potential of revealing sensitive information about the kernel state. Satisfies: SRG-OS-000132-GPOS-00067, SRG-OS-000480-GPOS-00227
SRG-OS-000132-GPOS-00067
1 Rule
RHEL 9 must restrict usage of ptrace to descendant processes.
Medium Severity
Unrestricted usage of ptrace allows compromised binaries to run ptrace on other processes of the user. Like this, the attacker can steal sensitive information from the target processes (e.g., SSH sessions, web browser, etc.) without any additional assistance from the user (i.e., without resorting to phishing). Satisfies: SRG-OS-000132-GPOS-00067, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must disable core dump backtraces.
Medium Severity
A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers or system operators trying to debug problems. Enabling core dumps on production systems is not recommended; however, there may be overriding operational requirements to enable advanced debugging. Permitting temporary enablement of core dumps during such situations must be reviewed through local needs and policy.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must disable storing core dumps.
Medium Severity
A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers or system operators trying to debug problems. Enabling core dumps on production systems is not recommended; however, there may be overriding operational requirements to enable advanced debugging. Permitting temporary enablement of core dumps during such situations must be reviewed through local needs and policy.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must disable core dumps for all users.
Medium Severity
A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers trying to debug problems.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must disable acquiring, saving, and processing core dumps.
Medium Severity
A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers trying to debug problems.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must disable the use of user namespaces.
Medium Severity
User namespaces are used primarily for Linux containers. The value "0" disallows the use of user namespaces.
SRG-OS-000433-GPOS-00192
1 Rule
RHEL 9 must implement nonexecutable data to protect its memory from unauthorized code execution.
Medium Severity
ExecShield uses the segmentation feature on all x86 systems to prevent execution in memory higher than a certain address. It writes an address as a limit in the code segment descriptor, to control where code can be executed, on a per-process basis. When the kernel places a process's memory regions such as the stack and heap higher than this address, the hardware prevents execution in that address range. This is enabled by default on the latest Red Hat and Fedora systems if supported by the hardware.
SRG-OS-000480-GPOS-00227
1 Rule
The kdump service on RHEL 9 must be disabled.
Medium Severity
Kernel core dumps may contain the full contents of system memory at the time of the crash. Kernel core dumps consume a considerable amount of disk space and may result in denial of service by exhausting the available space on the target file system partition. Unless the system is used for kernel development or testing, there is little need to run the kdump service.
SRG-OS-000366-GPOS-00153
1 Rule
RHEL 9 must ensure cryptographic verification of vendor software packages.
Medium Severity
Cryptographic verification of vendor software packages ensures that all software packages are obtained from a valid source and protects against spoofing that could lead to installation of malware on the system. Red Hat cryptographically signs all software packages, which includes updates, with a GPG key to verify that they are valid.
SRG-OS-000366-GPOS-00153
1 Rule
RHEL 9 must check the GPG signature of software packages originating from external software repositories before installation.
High Severity
Changes to any software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor. All software packages must be signed with a cryptographic key recognized and approved by the organization. Verifying the authenticity of software prior to installation validates the integrity of the software package received from a vendor. This verifies the software has not been tampered with and that it has been provided by a trusted vendor.
SRG-OS-000366-GPOS-00153
1 Rule
RHEL 9 must check the GPG signature of locally installed software packages before installation.
High Severity
Changes to any software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor. All software packages must be signed with a cryptographic key recognized and approved by the organization. Verifying the authenticity of software prior to installation validates the integrity of the software package received from a vendor. This verifies the software has not been tampered with and that it has been provided by a trusted vendor.
SRG-OS-000366-GPOS-00153
1 Rule
RHEL 9 must have GPG signature verification enabled for all software repositories.
High Severity
Changes to any software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor. All software packages must be signed with a cryptographic key recognized and approved by the organization. Verifying the authenticity of software prior to installation validates the integrity of the software package received from a vendor. This verifies the software has not been tampered with and that it has been provided by a trusted vendor.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must be configured so that the cryptographic hashes of system files match vendor values.
Medium Severity
The hashes of important files such as system executables should match the information given by the RPM database. Executables with erroneous hashes could be a sign of nefarious activity on the system.
SRG-OS-000437-GPOS-00194
1 Rule
RHEL 9 must remove all software components after updated versions have been installed.
Low Severity
Previous versions of software components that are not removed from the information system after updates have been installed may be exploited by some adversaries.
SRG-OS-000366-GPOS-00153
1 Rule
RHEL 9 subscription-manager package must be installed.
Medium Severity
The Red Hat Subscription Manager application manages software subscriptions and software repositories for installed software products on the local system. It communicates with backend servers, such as the Red Hat Customer Portal or an on-premise instance of Subscription Asset Manager, to register the local system and grant access to software resources determined by the subscription entitlement.
SRG-OS-000074-GPOS-00042
1 Rule
RHEL 9 must not have a File Transfer Protocol (FTP) server package installed.
High Severity
The FTP service provides an unencrypted remote access that does not provide for the confidentiality and integrity of user passwords or the remote session. If a privileged user were to log on using this service, the privileged user password could be compromised. SSH or other encrypted file transfer methods must be used in place of this service. Removing the "vsftpd" package decreases the risk of accidental activation. Satisfies: SRG-OS-000074-GPOS-00042, SRG-OS-000095-GPOS-00049, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not have the sendmail package installed.
Medium Severity
The sendmail software was not developed with security in mind, and its design prevents it from being effectively contained by SELinux. Postfix must be used instead. Satisfies: SRG-OS-000480-GPOS-00227, SRG-OS-000095-GPOS-00049
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must not have the nfs-utils package installed.
Medium Severity
"nfs-utils" provides a daemon for the kernel NFS server and related tools. This package also contains the "showmount" program. "showmount" queries the mount daemon on a remote host for information about the Network File System (NFS) server on the remote host. For example, "showmount" can display the clients that are mounted on that host.
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must not have the ypserv package installed.
Medium Severity
The NIS service provides an unencrypted authentication service, which does not provide for the confidentiality and integrity of user passwords or the remote session. Removing the "ypserv" package decreases the risk of the accidental (or intentional) activation of NIS or NIS+ services.
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must not have the rsh-server package installed.
Medium Severity
The "rsh-server" service provides unencrypted remote access service, which does not provide for the confidentiality and integrity of user passwords or the remote session and has very weak authentication. If a privileged user were to login using this service, the privileged user password could be compromised. The "rsh-server" package provides several obsolete and insecure network services. Removing it decreases the risk of accidental (or intentional) activation of those services.
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must not have the telnet-server package installed.
Medium Severity
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities are often overlooked and therefore, may remain unsecure. They increase the risk to the platform by providing additional attack vectors. The telnet service provides an unencrypted remote access service, which does not provide for the confidentiality and integrity of user passwords or the remote session. If a privileged user were to login using this service, the privileged user password could be compromised. Removing the "telnet-server" package decreases the risk of accidental (or intentional) activation of the telnet service.
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must not have the gssproxy package installed.
Medium Severity
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore, may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services provided by default may not be necessary to support essential organizational operations (e.g., key missions, functions). The gssproxy package is a proxy for GSS API credential handling and could expose secrets on some networks. It is not needed for normal function of the OS. Satisfies: SRG-OS-000095-GPOS-00049, SRG-OS-000480-GPOS-00227
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must not have the iprutils package installed.
Medium Severity
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). The iprutils package provides a suite of utilities to manage and configure SCSI devices supported by the ipr SCSI storage device driver. Satisfies: SRG-OS-000095-GPOS-00049, SRG-OS-000480-GPOS-00227
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must not have the tuned package installed.
Medium Severity
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Operating systems are capable of providing a wide variety of functions and services. Some of the functions and services, provided by default, may not be necessary to support essential organizational operations (e.g., key missions, functions). The tuned package contains a daemon that tunes the system settings dynamically. It does so by monitoring the usage of several system components periodically. Based on that information, components will then be put into lower or higher power savings modes to adapt to the current usage. The tuned package is not needed for normal OS operations. Satisfies: SRG-OS-000095-GPOS-00049, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not have a Trivial File Transfer Protocol (TFTP) server package installed.
High Severity
Removing the "tftp-server" package decreases the risk of the accidental (or intentional) activation of tftp services. If TFTP is required for operational support (such as transmission of router configurations), its use must be documented with the information systems security manager (ISSM), restricted to only authorized personnel, and have access control rules established.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not have the quagga package installed.
Medium Severity
Quagga is a network routing software suite providing implementations of Open Shortest Path First (OSPF), Routing Information Protocol (RIP), Border Gateway Protocol (BGP) for Unix and Linux platforms. If there is no need to make the router software available, removing it provides a safeguard against its activation.
SRG-OS-000480-GPOS-00227
1 Rule
A graphical display manager must not be installed on RHEL 9 unless approved.
Medium Severity
Unnecessary service packages must not be installed to decrease the attack surface of the system. Graphical display managers have a long history of security vulnerabilities and must not be used, unless approved and documented.
SRG-OS-000105-GPOS-00052
1 Rule
RHEL 9 must have the openssl-pkcs11 package installed.
Medium Severity
Without the use of multifactor authentication, the ease of access to privileged functions is greatly increased. Multifactor authentication requires using two or more factors to achieve authentication. A privileged account is defined as an information system account with authorizations of a privileged user. The DOD common access card (CAC) with DOD-approved PKI is an example of multifactor authentication. Satisfies: SRG-OS-000105-GPOS-00052, SRG-OS-000375-GPOS-00160, SRG-OS-000376-GPOS-00161, SRG-OS-000377-GPOS-00162
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must have the gnutls-utils package installed.
Medium Severity
GnuTLS is a secure communications library implementing the SSL, TLS and DTLS protocols and technologies around them. It provides a simple C language application programming interface (API) to access the secure communications protocols as well as APIs to parse and write X.509, PKCS #12, OpenPGP and other required structures. This package contains command line TLS client and server and certificate manipulation tools.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must have the nss-tools package installed.
Medium Severity
Network Security Services (NSS) is a set of libraries designed to support cross-platform development of security-enabled client and server applications. Install the "nss-tools" package to install command-line tools to manipulate the NSS certificate and key database.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must have the rng-tools package installed.
Medium Severity
"rng-tools" provides hardware random number generator tools, such as those used in the formation of x509/PKI certificates.
SRG-OS-000363-GPOS-00150
1 Rule
RHEL 9 must have the s-nail package installed.
Medium Severity
The "s-nail" package provides the mail command required to allow sending email notifications of unauthorized configuration changes to designated personnel.
SRG-OS-000480-GPOS-00227
1 Rule
A separate RHEL 9 file system must be used for user home directories (such as /home or an equivalent).
Medium Severity
Ensuring that "/home" is mounted on its own partition enables the setting of more restrictive mount options, and also helps ensure that users cannot trivially fill partitions used for log or audit data storage.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must use a separate file system for /tmp.
Medium Severity
The "/tmp" partition is used as temporary storage by many programs. Placing "/tmp" in its own partition enables the setting of more restrictive mount options, which can help protect programs that use it.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must use a separate file system for /var.
Low Severity
Ensuring that "/var" is mounted on its own partition enables the setting of more restrictive mount options. This helps protect system services such as daemons or other programs which use it. It is not uncommon for the "/var" directory to contain world-writable directories installed by other software packages.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must use a separate file system for /var/log.
Low Severity
Placing "/var/log" in its own partition enables better separation between log files and other files in "/var/".
SRG-OS-000341-GPOS-00132
1 Rule
RHEL 9 must use a separate file system for the system audit data path.
Low Severity
Placing "/var/log/audit" in its own partition enables better separation between audit files and other system files, and helps ensure that auditing cannot be halted due to the partition running out of space. Satisfies: SRG-OS-000341-GPOS-00132, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must use a separate file system for /var/tmp.
Medium Severity
The "/var/tmp" partition is used as temporary storage by many programs. Placing "/var/tmp" in its own partition enables the setting of more restrictive mount options, which can help protect programs that use it.
SRG-OS-000114-GPOS-00059
1 Rule
RHEL 9 file system automount function must be disabled unless required.
Medium Severity
An authentication process resists replay attacks if it is impractical to achieve a successful authentication by recording and replaying a previous authentication message. Satisfies: SRG-OS-000114-GPOS-00059, SRG-OS-000378-GPOS-00163, SRG-OS-000480-GPOS-00227
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must prevent device files from being interpreted on file systems that contain user home directories.
Medium Severity
The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access. The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must prevent files with the setuid and setgid bit set from being executed on file systems that contain user home directories.
Medium Severity
The "nosuid" mount option causes the system to not execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access. Satisfies: SRG-OS-000368-GPOS-00154, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent code from being executed on file systems that contain user home directories.
Medium Severity
The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary files, as they may be incompatible. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent special devices on file systems that are imported via Network File System (NFS).
Medium Severity
The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent code from being executed on file systems that are imported via Network File System (NFS).
Medium Severity
The "noexec" mount option causes the system not to execute binary files. This option must be used for mounting any file system not containing approved binary as they may be incompatible. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent files with the setuid and setgid bit set from being executed on file systems that are imported via Network File System (NFS).
Medium Severity
The "nosuid" mount option causes the system not to execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent code from being executed on file systems that are used with removable media.
Medium Severity
The "noexec" mount option causes the system not to execute binary files. This option must be used for mounting any file system not containing approved binary files, as they may be incompatible. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent special devices on file systems that are used with removable media.
Medium Severity
The "nodev" mount option causes the system not to interpret character or block special devices. Executing character or blocking special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent files with the setuid and setgid bit set from being executed on file systems that are used with removable media.
Medium Severity
The "nosuid" mount option causes the system not to execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /boot with the nodev option.
Medium Severity
The only legitimate location for device files is the "/dev" directory located on the root partition. The only exception to this is chroot jails.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must prevent files with the setuid and setgid bit set from being executed on the /boot directory.
Medium Severity
The "nosuid" mount option causes the system not to execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access. Satisfies: SRG-OS-000368-GPOS-00154, SRG-OS-000480-GPOS-00227
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must prevent files with the setuid and setgid bit set from being executed on the /boot/efi directory.
Medium Severity
The "nosuid" mount option causes the system not to execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access. Satisfies: SRG-OS-000368-GPOS-00154, SRG-OS-000480-GPOS-00227
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /dev/shm with the nodev option.
Medium Severity
The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access. The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /dev/shm with the noexec option.
Medium Severity
The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary files, as they may be incompatible. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /dev/shm with the nosuid option.
Medium Severity
The "nosuid" mount option causes the system to not execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /tmp with the nodev option.
Medium Severity
The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access. The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /tmp with the noexec option.
Medium Severity
The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary files, as they may be incompatible. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /tmp with the nosuid option.
Medium Severity
The "nosuid" mount option causes the system to not execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /var with the nodev option.
Medium Severity
The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access. The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /var/log with the nodev option.
Medium Severity
The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access. The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /var/log with the noexec option.
Medium Severity
The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary files, as they may be incompatible. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /var/log with the nosuid option.
Medium Severity
The "nosuid" mount option causes the system to not execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /var/log/audit with the nodev option.
Medium Severity
The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access. The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /var/log/audit with the noexec option.
Medium Severity
The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary files, as they may be incompatible. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /var/log/audit with the nosuid option.
Medium Severity
The "nosuid" mount option causes the system to not execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /var/tmp with the nodev option.
Medium Severity
The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access. The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /var/tmp with the noexec option.
Medium Severity
The "noexec" mount option causes the system to not execute binary files. This option must be used for mounting any file system not containing approved binary files, as they may be incompatible. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must mount /var/tmp with the nosuid option.
Medium Severity
The "nosuid" mount option causes the system to not execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access.
SRG-OS-000405-GPOS-00184
1 Rule
RHEL 9 local disk partitions must implement cryptographic mechanisms to prevent unauthorized disclosure or modification of all information that requires at rest protection.
High Severity
RHEL 9 systems handling data requiring "data at rest" protections must employ cryptographic mechanisms to prevent unauthorized disclosure and modification of the information at rest. Selection of a cryptographic mechanism is based on the need to protect the integrity of organizational information. The strength of the mechanism is commensurate with the security category and/or classification of the information. Organizations have the flexibility to either encrypt all information on storage devices (i.e., full disk encryption) or encrypt specific data structures (e.g., files, records, or fields). Satisfies: SRG-OS-000405-GPOS-00184, SRG-OS-000185-GPOS-00079, SRG-OS-000404-GPOS-00183
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 must disable mounting of cramfs.
Low Severity
It is detrimental for operating systems to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked and therefore may remain unsecured. They increase the risk to the platform by providing additional attack vectors. Removing support for unneeded filesystem types reduces the local attack surface of the server. Compressed ROM/RAM file system (or cramfs) is a read-only file system designed for simplicity and space-efficiency. It is mainly used in embedded and small-footprint systems.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent special devices on non-root local partitions.
Medium Severity
The "nodev" mount option causes the system to not interpret character or block special devices. Executing character or block special devices from untrusted file systems increases the opportunity for nonprivileged users to attain unauthorized administrative access. The only legitimate location for device files is the "/dev" directory located on the root partition, with the exception of chroot jails if implemented.
SRG-OS-000259-GPOS-00100
1 Rule
RHEL 9 system commands must have mode 755 or less permissive.
Medium Severity
If RHEL 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to RHEL 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.
SRG-OS-000259-GPOS-00100
1 Rule
RHEL 9 library directories must have mode 755 or less permissive.
Medium Severity
If RHEL 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to RHEL 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.
SRG-OS-000259-GPOS-00100
1 Rule
RHEL 9 library files must have mode 755 or less permissive.
Medium Severity
If RHEL 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to RHEL 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.
SRG-OS-000206-GPOS-00084
1 Rule
RHEL 9 /var/log directory must have mode 0755 or less permissive.
Medium Severity
Only authorized personnel should be aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can identify the RHEL 9 system or platform. Additionally, personally identifiable information (PII) and operational information must not be revealed through error messages to unauthorized personnel or their designated representatives. The structure and content of error messages must be carefully considered by the organization and development team. The extent to which the information system is able to identify and handle error conditions is guided by organizational policy and operational requirements.
SRG-OS-000206-GPOS-00084
1 Rule
RHEL 9 /var/log/messages file must have mode 0640 or less permissive.
Medium Severity
Only authorized personnel should be aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can identify the RHEL 9 system or platform. Additionally, personally identifiable information (PII) and operational information must not be revealed through error messages to unauthorized personnel or their designated representatives. The structure and content of error messages must be carefully considered by the organization and development team. The extent to which the information system is able to identify and handle error conditions is guided by organizational policy and operational requirements.
SRG-OS-000256-GPOS-00097
1 Rule
RHEL 9 audit tools must have a mode of 0755 or less permissive.
Medium Severity
Protecting audit information also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operation on audit information. RHEL 9 systems providing tools to interface with audit information will leverage user permissions and roles identifying the user accessing the tools, and the corresponding rights the user enjoys, to make access decisions regarding the access to audit tools. Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 cron configuration directories must have a mode of 0700 or less permissive.
Medium Severity
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should have the correct access rights to prevent unauthorized changes.
SRG-OS-000480-GPOS-00227
1 Rule
All RHEL 9 local initialization files must have mode 0740 or less permissive.
Medium Severity
Local initialization files are used to configure the user's shell environment upon logon. Malicious modification of these files could compromise accounts upon logon.
SRG-OS-000480-GPOS-00227
1 Rule
All RHEL 9 local interactive user home directories must have mode 0750 or less permissive.
Medium Severity
Excessive permissions on local interactive user home directories may allow unauthorized access to user files by other users.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/group file must have mode 0644 or less permissive to prevent unauthorized access.
Medium Severity
The "/etc/group" file contains information regarding groups that are configured on the system. Protection of this file is important for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/group- file must have mode 0644 or less permissive to prevent unauthorized access.
Medium Severity
The "/etc/group-" file is a backup file of "/etc/group", and as such, contains information regarding groups that are configured on the system. Protection of this file is important for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/gshadow file must have mode 0000 or less permissive to prevent unauthorized access.
Medium Severity
The "/etc/gshadow" file contains group password hashes. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/gshadow- file must have mode 0000 or less permissive to prevent unauthorized access.
Medium Severity
The "/etc/gshadow-" file is a backup of "/etc/gshadow", and as such, contains group password hashes. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/passwd file must have mode 0644 or less permissive to prevent unauthorized access.
Medium Severity
If the "/etc/passwd" file is writable by a group-owner or the world the risk of its compromise is increased. The file contains the list of accounts on the system and associated information, and protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/passwd- file must have mode 0644 or less permissive to prevent unauthorized access.
Medium Severity
The "/etc/passwd-" file is a backup file of "/etc/passwd", and as such, contains information about the users that are configured on the system. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/shadow- file must have mode 0000 or less permissive to prevent unauthorized access.
Medium Severity
The "/etc/shadow-" file is a backup file of "/etc/shadow", and as such, contains the list of local system accounts and password hashes. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/group file must be owned by root.
Medium Severity
The "/etc/group" file contains information regarding groups that are configured on the system. Protection of this file is important for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/group file must be group-owned by root.
Medium Severity
The "/etc/group" file contains information regarding groups that are configured on the system. Protection of this file is important for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/group- file must be owned by root.
Medium Severity
The "/etc/group-" file is a backup file of "/etc/group", and as such, contains information regarding groups that are configured on the system. Protection of this file is important for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/group- file must be group-owned by root.
Medium Severity
The "/etc/group-" file is a backup file of "/etc/group", and as such, contains information regarding groups that are configured on the system. Protection of this file is important for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/gshadow file must be owned by root.
Medium Severity
The "/etc/gshadow" file contains group password hashes. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/gshadow file must be group-owned by root.
Medium Severity
The "/etc/gshadow" file contains group password hashes. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/gshadow- file must be owned by root.
Medium Severity
The "/etc/gshadow-" file is a backup of "/etc/gshadow", and as such, contains group password hashes. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/gshadow- file must be group-owned by root.
Medium Severity
The "/etc/gshadow-" file is a backup of "/etc/gshadow", and as such, contains group password hashes. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/passwd file must be owned by root.
Medium Severity
The "/etc/passwd" file contains information about the users that are configured on the system. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/passwd file must be group-owned by root.
Medium Severity
The "/etc/passwd" file contains information about the users that are configured on the system. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/passwd- file must be owned by root.
Medium Severity
The "/etc/passwd-" file is a backup file of "/etc/passwd", and as such, contains information about the users that are configured on the system. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/passwd- file must be group-owned by root.
Medium Severity
The "/etc/passwd-" file is a backup file of "/etc/passwd", and as such, contains information about the users that are configured on the system. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/shadow file must be owned by root.
Medium Severity
The "/etc/shadow" file contains the list of local system accounts and stores password hashes. Protection of this file is critical for system security. Failure to give ownership of this file to root provides the designated owner with access to sensitive information, which could weaken the system security posture.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/shadow file must be group-owned by root.
Medium Severity
The "/etc/shadow" file stores password hashes. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/shadow- file must be owned by root.
Medium Severity
The "/etc/shadow-" file is a backup file of "/etc/shadow", and as such, contains the list of local system accounts and password hashes. Protection of this file is critical for system security.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/shadow- file must be group-owned by root.
Medium Severity
The "/etc/shadow-" file is a backup file of "/etc/shadow", and as such, contains the list of local system accounts and password hashes. Protection of this file is critical for system security.
SRG-OS-000206-GPOS-00084
1 Rule
RHEL 9 /var/log directory must be owned by root.
Medium Severity
Only authorized personnel should be aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can identify the RHEL 9 system or platform. Additionally, personally identifiable information (PII) and operational information must not be revealed through error messages to unauthorized personnel or their designated representatives. The structure and content of error messages must be carefully considered by the organization and development team. The extent to which the information system is able to identify and handle error conditions is guided by organizational policy and operational requirements.
SRG-OS-000206-GPOS-00084
1 Rule
RHEL 9 /var/log directory must be group-owned by root.
Medium Severity
Only authorized personnel should be aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can identify the RHEL 9 system or platform. Additionally, personally identifiable information (PII) and operational information must not be revealed through error messages to unauthorized personnel or their designated representatives. The structure and content of error messages must be carefully considered by the organization and development team. The extent to which the information system is able to identify and handle error conditions is guided by organizational policy and operational requirements.
SRG-OS-000206-GPOS-00084
1 Rule
RHEL 9 /var/log/messages file must be owned by root.
Medium Severity
Only authorized personnel should be aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can identify the RHEL 9 system or platform. Additionally, personally identifiable information (PII) and operational information must not be revealed through error messages to unauthorized personnel or their designated representatives. The structure and content of error messages must be carefully considered by the organization and development team. The extent to which the information system is able to identify and handle error conditions is guided by organizational policy and operational requirements.
SRG-OS-000206-GPOS-00084
1 Rule
RHEL 9 /var/log/messages file must be group-owned by root.
Medium Severity
Only authorized personnel should be aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can identify the RHEL 9 system or platform. Additionally, personally identifiable information (PII) and operational information must not be revealed through error messages to unauthorized personnel or their designated representatives. The structure and content of error messages must be carefully considered by the organization and development team. The extent to which the information system is able to identify and handle error conditions is guided by organizational policy and operational requirements.
SRG-OS-000259-GPOS-00100
1 Rule
RHEL 9 system commands must be owned by root.
Medium Severity
If RHEL 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to RHEL 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.
SRG-OS-000259-GPOS-00100
1 Rule
RHEL 9 system commands must be group-owned by root or a system account.
Medium Severity
If RHEL 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to RHEL 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.
SRG-OS-000259-GPOS-00100
1 Rule
RHEL 9 library files must be owned by root.
Medium Severity
If RHEL 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to RHEL 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.
SRG-OS-000259-GPOS-00100
1 Rule
RHEL 9 library files must be group-owned by root or a system account.
Medium Severity
If RHEL 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to RHEL 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.
SRG-OS-000259-GPOS-00100
1 Rule
RHEL 9 library directories must be owned by root.
Medium Severity
If RHEL 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to RHEL 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.
SRG-OS-000259-GPOS-00100
1 Rule
RHEL 9 library directories must be group-owned by root or a system account.
Medium Severity
If RHEL 9 allowed any user to make changes to software libraries, then those changes might be implemented without undergoing the appropriate testing and approvals that are part of a robust change management process. This requirement applies to RHEL 9 with software libraries that are accessible and configurable, as in the case of interpreted languages. Software libraries also include privileged programs that execute with escalated privileges.
SRG-OS-000256-GPOS-00097
1 Rule
RHEL 9 audit tools must be owned by root.
Medium Severity
Protecting audit information also includes identifying and protecting the tools used to view and manipulate log data. Therefore, protecting audit tools is necessary to prevent unauthorized operation on audit information. RHEL 9 systems providing tools to interface with audit information will leverage user permissions and roles identifying the user accessing the tools, and the corresponding rights the user enjoys, to make access decisions regarding the access to audit tools. Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators.
SRG-OS-000256-GPOS-00097
1 Rule
RHEL 9 audit tools must be group-owned by root.
Medium Severity
Protecting audit information also includes identifying and protecting the tools used to view and manipulate log data; therefore, protecting audit tools is necessary to prevent unauthorized operation on audit information. RHEL 9 systems providing tools to interface with audit information will leverage user permissions and roles identifying the user accessing the tools, and the corresponding rights the user enjoys, to make access decisions regarding the access to audit tools. Audit tools include, but are not limited to, vendor-provided and open source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 cron configuration files directory must be owned by root.
Medium Severity
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations; therefore, service configuration files must be owned by the correct group to prevent unauthorized changes.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 cron configuration files directory must be group-owned by root.
Medium Severity
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations; therefore, service configuration files should be owned by the correct group to prevent unauthorized changes.
SRG-OS-000480-GPOS-00227
1 Rule
All RHEL 9 world-writable directories must be owned by root, sys, bin, or an application user.
Medium Severity
If a world-writable directory is not owned by root, sys, bin, or an application user identifier (UID), unauthorized users may be able to modify files created by others. The only authorized public directories are those temporary directories supplied with the system or those designed to be temporary file repositories. The setting is normally reserved for directories used by the system and by users for temporary file storage, (e.g., /tmp), and for directories requiring global read/write access. Satisfies: SRG-OS-000480-GPOS-00227, SRG-OS-000138-GPOS-00069
SRG-OS-000138-GPOS-00069
1 Rule
A sticky bit must be set on all RHEL 9 public directories.
Medium Severity
Preventing unauthorized information transfers mitigates the risk of information, including encrypted representations of information, produced by the actions of prior users/roles (or the actions of processes acting on behalf of prior users/roles) from being available to any current users/roles (or current processes) that obtain access to shared system resources (e.g., registers, main memory, hard disks) after those resources have been released back to information systems. The control of information in shared resources is also commonly referred to as object reuse and residual information protection. This requirement generally applies to the design of an information technology product, but it can also apply to the configuration of particular information system components that are, or use, such products. This can be verified by acceptance/validation processes in DOD or other government agencies.
SRG-OS-000480-GPOS-00227
1 Rule
All RHEL 9 local files and directories must have a valid group owner.
Medium Severity
Files without a valid group owner may be unintentionally inherited if a group is assigned the same Group Identifier (GID) as the GID of the files without a valid group owner.
SRG-OS-000480-GPOS-00227
1 Rule
All RHEL 9 local files and directories must have a valid owner.
Medium Severity
Unowned files and directories may be unintentionally inherited if a user is assigned the same user identifier "UID" as the UID of the unowned files.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must be configured so that all system device files are correctly labeled to prevent unauthorized modification.
Medium Severity
If an unauthorized or modified device is allowed to exist on the system, there is the possibility the system may perform unintended or unauthorized operations.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/crontab file must have mode 0600.
Medium Severity
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations; therefore, service configuration files must have the correct access rights to prevent unauthorized changes.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 /etc/shadow file must have mode 0000 to prevent unauthorized access.
Medium Severity
The "/etc/shadow" file contains the list of local system accounts and stores password hashes. Protection of this file is critical for system security. Failure to give ownership of this file to root provides the designated owner with access to sensitive information, which could weaken the system security posture.
SRG-OS-000096-GPOS-00050
1 Rule
RHEL 9 must have the firewalld package installed.
Medium Severity
"Firewalld" provides an easy and effective way to block/limit remote access to the system via ports, services, and protocols. Remote access services, such as those providing remote access to network devices and information systems, which lack automated control capabilities, increase risk and make remote user access management difficult at best. Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. RHEL 9 functionality (e.g., SSH) must be capable of taking enforcement action if the audit reveals unauthorized activity. Automated control of remote access sessions allows organizations to ensure ongoing compliance with remote access policies by enforcing connection rules of remote access applications on a variety of information system components (e.g., servers, workstations, notebook computers, smartphones, and tablets). Satisfies: SRG-OS-000096-GPOS-00050, SRG-OS-000297-GPOS-00115, SRG-OS-000298-GPOS-00116, SRG-OS-000480-GPOS-00227, SRG-OS-000480-GPOS-00232
SRG-OS-000096-GPOS-00050
1 Rule
The firewalld service on RHEL 9 must be active.
Medium Severity
"Firewalld" provides an easy and effective way to block/limit remote access to the system via ports, services, and protocols. Remote access services, such as those providing remote access to network devices and information systems, which lack automated control capabilities, increase risk and make remote user access management difficult at best. Remote access is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, non-organization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. RHEL 9 functionality (e.g., RDP) must be capable of taking enforcement action if the audit reveals unauthorized activity. Automated control of remote access sessions allows organizations to ensure ongoing compliance with remote access policies by enforcing connection rules of remote access applications on a variety of information system components (e.g., servers, workstations, notebook computers, smartphones, and tablets). Satisfies: SRG-OS-000096-GPOS-00050, SRG-OS-000297-GPOS-00115, SRG-OS-000480-GPOS-00227, SRG-OS-000480-GPOS-00232
SRG-OS-000480-GPOS-00227
1 Rule
A RHEL 9 firewall must employ a deny-all, allow-by-exception policy for allowing connections to other systems.
Medium Severity
Failure to restrict network connectivity only to authorized systems permits inbound connections from malicious systems. It also permits outbound connections that may facilitate exfiltration of DOD data. RHEL 9 incorporates the "firewalld" daemon, which allows for many different configurations. One of these configurations is zones. Zones can be utilized to a deny-all, allow-by-exception approach. The default "drop" zone will drop all incoming network packets unless it is explicitly allowed by the configuration file or is related to an outgoing network connection.
SRG-OS-000420-GPOS-00186
1 Rule
RHEL 9 must protect against or limit the effects of denial-of-service (DoS) attacks by ensuring rate-limiting measures on impacted network interfaces are implemented.
Medium Severity
DoS is a condition when a resource is not available for legitimate users. When this occurs, the organization either cannot accomplish its mission or must operate at degraded capacity. This requirement addresses the configuration of RHEL 9 to mitigate the impact of DoS attacks that have occurred or are ongoing on system availability. For each system, known and potential DoS attacks must be identified and solutions for each type implemented. A variety of technologies exists to limit or, in some cases, eliminate the effects of DoS attacks (e.g., limiting processes or establishing memory partitions). Employing increased capacity and bandwidth, combined with service redundancy, may reduce the susceptibility to some DoS attacks.
SRG-OS-000096-GPOS-00050
1 Rule
RHEL 9 must be configured to prohibit or restrict the use of functions, ports, protocols, and/or services, as defined in the Ports, Protocols, and Services Management (PPSM) Category Assignments List (CAL) and vulnerability assessments.
Medium Severity
To prevent unauthorized connection of devices, unauthorized transfer of information, or unauthorized tunneling (i.e., embedding of data types within data types), organizations must disable or restrict unused or unnecessary ports, protocols, and services on information systems.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 network interfaces must not be in promiscuous mode.
Medium Severity
Network interfaces in promiscuous mode allow for the capture of all network traffic visible to the system. If unauthorized individuals can access these applications, it may allow them to collect information such as logon IDs, passwords, and key exchanges between systems. If the system is being used to perform a network troubleshooting function, the use of these tools must be documented with the information systems security officer (ISSO) and restricted to only authorized personnel.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must enable hardening for the Berkeley Packet Filter just-in-time compiler.
Medium Severity
When hardened, the extended Berkeley Packet Filter (BPF) just-in-time (JIT) compiler will randomize any kernel addresses in the BPF programs and maps, and will not expose the JIT addresses in "/proc/kallsyms".
SRG-OS-000355-GPOS-00143
1 Rule
RHEL 9 must have the chrony package installed.
Medium Severity
Inaccurate time stamps make it more difficult to correlate events and can lead to an inaccurate analysis. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events. Sources outside the configured acceptable allowance (drift) may be inaccurate.
SRG-OS-000355-GPOS-00143
1 Rule
RHEL 9 chronyd service must be enabled.
Medium Severity
Inaccurate time stamps make it more difficult to correlate events and can lead to an inaccurate analysis. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events. Sources outside the configured acceptable allowance (drift) may be inaccurate. Synchronizing internal information system clocks provides uniformity of time stamps for information systems with multiple system clocks and systems connected over a network.
SRG-OS-000355-GPOS-00143
1 Rule
RHEL 9 must securely compare internal information system clocks at least every 24 hours.
Medium Severity
Inaccurate time stamps make it more difficult to correlate events and can lead to an inaccurate analysis. Determining the correct time a particular event occurred on a system is critical when conducting forensic analysis and investigating system events. Sources outside the configured acceptable allowance (drift) may be inaccurate. Synchronizing internal information system clocks provides uniformity of time stamps for information systems with multiple system clocks and systems connected over a network. Depending on the infrastructure being used the "pool" directive may not be supported. Authoritative time sources include the United States Naval Observatory (USNO) time servers, a time server designated for the appropriate DOD network (NIPRNet/SIPRNet), and/or the Global Positioning System (GPS). Satisfies: SRG-OS-000355-GPOS-00143, SRG-OS-000356-GPOS-00144, SRG-OS-000359-GPOS-00146
SRG-OS-000096-GPOS-00050
1 Rule
RHEL 9 must disable the chrony daemon from acting as a server.
Low Severity
Minimizing the exposure of the server functionality of the chrony daemon diminishes the attack surface. Satisfies: SRG-OS-000096-GPOS-00050, SRG-OS-000095-GPOS-00049
SRG-OS-000096-GPOS-00050
1 Rule
RHEL 9 must disable network management of the chrony daemon.
Low Severity
Not exposing the management interface of the chrony daemon on the network diminishes the attack space. Satisfies: SRG-OS-000096-GPOS-00050, SRG-OS-000095-GPOS-00049
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 systems using Domain Name Servers (DNS) resolution must have at least two name servers configured.
Medium Severity
To provide availability for name resolution services, multiple redundant name servers are mandated. A failure in name resolution could lead to the failure of security functions requiring name resolution, which may include time synchronization, centralized authentication, and remote system logging.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must configure a DNS processing mode in Network Manager.
Medium Severity
In order to ensure that DNS resolver settings are respected, a DNS mode in Network Manager must be configured.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not have unauthorized IP tunnels configured.
Medium Severity
IP tunneling mechanisms can be used to bypass network filtering. If tunneling is required, it must be documented with the information system security officer (ISSO).
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must be configured to prevent unrestricted mail relaying.
Medium Severity
If unrestricted mail relaying is permitted, unauthorized senders could use this host as a mail relay for the purpose of sending spam or other unauthorized activity.
SRG-OS-000046-GPOS-00022
1 Rule
RHEL 9 must forward mail from postmaster to the root account using a postfix alias.
Medium Severity
It is critical for the appropriate personnel to be aware if a system is at risk of failing to process audit logs as required. Without this notification, the security personnel may be unaware of an impending failure of the audit capability, and system operation may be adversely affected. Audit processing failures include software/hardware errors, failures in the audit capturing mechanisms, and audit storage capacity being reached or exceeded.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 libreswan package must be installed.
Medium Severity
Providing the ability for remote users or systems to initiate a secure VPN connection protects information when it is transmitted over a wide area network. Satisfies: SRG-OS-000480-GPOS-00227, SRG-OS-000120-GPOS-00061
SRG-OS-000480-GPOS-00227
1 Rule
There must be no shosts.equiv files on RHEL 9.
High Severity
The shosts.equiv files are used to configure host-based authentication for the system via SSH. Host-based authentication is not sufficient for preventing unauthorized access to the system, as it does not require interactive identification and authentication of a connection request, or for the use of two-factor authentication.
SRG-OS-000480-GPOS-00227
1 Rule
There must be no .shosts files on RHEL 9.
High Severity
The .shosts files are used to configure host-based authentication for individual users or the system via SSH. Host-based authentication is not sufficient for preventing unauthorized access to the system, as it does not require interactive identification and authentication of a connection request, or for the use of two-factor authentication.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must be configured to use TCP syncookies.
Medium Severity
Denial of service (DoS) is a condition when a resource is not available for legitimate users. When this occurs, the organization either cannot accomplish its mission or must operate at degraded capacity. Managing excess capacity ensures that sufficient capacity is available to counter flooding attacks. Employing increased capacity and service redundancy may reduce the susceptibility to some DoS attacks. Managing excess capacity may include, for example, establishing selected usage priorities, quotas, or partitioning. Satisfies: SRG-OS-000480-GPOS-00227, SRG-OS-000420-GPOS-00186, SRG-OS-000142-GPOS-00071
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must ignore Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages.
Medium Severity
ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages modify the host's route table and are unauthenticated. An illicit ICMP redirect message could result in a man-in-the-middle attack. This feature of the IPv4 protocol has few legitimate uses. It should be disabled unless absolutely required.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not forward Internet Protocol version 4 (IPv4) source-routed packets.
Medium Severity
Source-routed packets allow the source of the packet to suggest routers forward the packet along a different path than configured on the router, which can be used to bypass network security measures. This requirement applies only to the forwarding of source-routerd traffic, such as when IPv4 forwarding is enabled and the system is functioning as a router. Accepting source-routed packets in the IPv4 protocol has few legitimate uses. It must be disabled unless it is absolutely required.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must log IPv4 packets with impossible addresses.
Medium Severity
The presence of "martian" packets (which have impossible addresses) as well as spoofed packets, source-routed packets, and redirects could be a sign of nefarious network activity. Logging these packets enables this activity to be detected.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must log IPv4 packets with impossible addresses by default.
Medium Severity
The presence of "martian" packets (which have impossible addresses) as well as spoofed packets, source-routed packets, and redirects could be a sign of nefarious network activity. Logging these packets enables this activity to be detected.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must use reverse path filtering on all IPv4 interfaces.
Medium Severity
Enabling reverse path filtering drops packets with source addresses that should not have been able to be received on the interface on which they were received. It must not be used on systems that are routers for complicated networks, but is helpful for end hosts and routers serving small networks.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent IPv4 Internet Control Message Protocol (ICMP) redirect messages from being accepted.
Medium Severity
ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages modify the host's route table and are unauthenticated. An illicit ICMP redirect message could result in a man-in-the-middle attack. This feature of the IPv4 protocol has few legitimate uses. It must be disabled unless absolutely required.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not forward IPv4 source-routed packets by default.
Medium Severity
Source-routed packets allow the source of the packet to suggest routers forward the packet along a different path than configured on the router, which can be used to bypass network security measures. Accepting source-routed packets in the IPv4 protocol has few legitimate uses. It must be disabled unless it is absolutely required, such as when IPv4 forwarding is enabled and the system is legitimately functioning as a router.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must use a reverse-path filter for IPv4 network traffic when possible by default.
Medium Severity
Enabling reverse path filtering drops packets with source addresses that should not have been able to be received on the interface on which they were received. It must not be used on systems that are routers for complicated networks, but is helpful for end hosts and routers serving small networks.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not respond to Internet Control Message Protocol (ICMP) echoes sent to a broadcast address.
Medium Severity
Responding to broadcast (ICMP) echoes facilitates network mapping and provides a vector for amplification attacks. Ignoring ICMP echo requests (pings) sent to broadcast or multicast addresses makes the system slightly more difficult to enumerate on the network.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must limit the number of bogus Internet Control Message Protocol (ICMP) response errors logs.
Medium Severity
Some routers will send responses to broadcast frames that violate RFC-1122, which fills up a log file system with many useless error messages. An attacker may take advantage of this and attempt to flood the logs with bogus error logs. Ignoring bogus ICMP error responses reduces log size, although some activity would not be logged.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not send Internet Control Message Protocol (ICMP) redirects.
Medium Severity
ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages contain information from the system's route table possibly revealing portions of the network topology. The ability to send ICMP redirects is only appropriate for systems acting as routers.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not allow interfaces to perform Internet Control Message Protocol (ICMP) redirects by default.
Medium Severity
ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages contain information from the system's route table possibly revealing portions of the network topology. The ability to send ICMP redirects is only appropriate for systems acting as routers.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not enable IPv4 packet forwarding unless the system is a router.
Medium Severity
Routing protocol daemons are typically used on routers to exchange network topology information with other routers. If this capability is used when not required, system network information may be unnecessarily transmitted across the network.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not accept router advertisements on all IPv6 interfaces.
Medium Severity
An illicit router advertisement message could result in a man-in-the-middle attack.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must ignore IPv6 Internet Control Message Protocol (ICMP) redirect messages.
Medium Severity
An illicit ICMP redirect message could result in a man-in-the-middle attack.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not forward IPv6 source-routed packets.
Medium Severity
Source-routed packets allow the source of the packet to suggest that routers forward the packet along a different path than configured on the router, which can be used to bypass network security measures. This requirement applies only to the forwarding of source-routed traffic, such as when forwarding is enabled and the system is functioning as a router.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not enable IPv6 packet forwarding unless the system is a router.
Medium Severity
IP forwarding permits the kernel to forward packets from one network interface to another. The ability to forward packets between two networks is only appropriate for systems acting as routers.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not accept router advertisements on all IPv6 interfaces by default.
Medium Severity
An illicit router advertisement message could result in a man-in-the-middle attack.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent IPv6 Internet Control Message Protocol (ICMP) redirect messages from being accepted.
Medium Severity
ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages modify the host's route table and are unauthenticated. An illicit ICMP redirect message could result in a man-in-the-middle attack.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not forward IPv6 source-routed packets by default.
Medium Severity
Source-routed packets allow the source of the packet to suggest that routers forward the packet along a different path than configured on the router, which can be used to bypass network security measures. This requirement applies only to the forwarding of source-routed traffic, such as when forwarding is enabled and the system is functioning as a router. Accepting source-routed packets in the IPv6 protocol has few legitimate uses. It must be disabled unless it is absolutely required.
SRG-OS-000423-GPOS-00187
1 Rule
All RHEL 9 networked systems must have SSH installed.
Medium Severity
Without protection of the transmitted information, confidentiality and integrity may be compromised because unprotected communications can be intercepted and either read or altered. This requirement applies to both internal and external networks and all types of information system components from which information can be transmitted (e.g., servers, mobile devices, notebook computers, printers, copiers, scanners, and facsimile machines). Communication paths outside the physical protection of a controlled boundary are exposed to the possibility of interception and modification. Protecting the confidentiality and integrity of organizational information can be accomplished by physical means (e.g., employing physical distribution systems) or by logical means (e.g., employing cryptographic techniques). If physical means of protection are employed, then logical means (cryptography) do not have to be employed, and vice versa. Satisfies: SRG-OS-000423-GPOS-00187, SRG-OS-000424-GPOS-00188, SRG-OS-000425-GPOS-00189, SRG-OS-000426-GPOS-00190
SRG-OS-000423-GPOS-00187
1 Rule
All RHEL 9 networked systems must have and implement SSH to protect the confidentiality and integrity of transmitted and received information, as well as information during preparation for transmission.
Medium Severity
Without protection of the transmitted information, confidentiality and integrity may be compromised because unprotected communications can be intercepted and either read or altered. This requirement applies to both internal and external networks and all types of information system components from which information can be transmitted (e.g., servers, mobile devices, notebook computers, printers, copiers, scanners, and facsimile machines). Communication paths outside the physical protection of a controlled boundary are exposed to the possibility of interception and modification. Protecting the confidentiality and integrity of organizational information can be accomplished by physical means (e.g., employing physical distribution systems) or by logical means (e.g., employing cryptographic techniques). If physical means of protection are employed, then logical means (cryptography) do not have to be employed, and vice versa. Satisfies: SRG-OS-000423-GPOS-00187, SRG-OS-000424-GPOS-00188, SRG-OS-000425-GPOS-00189, SRG-OS-000426-GPOS-00190
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must have the openssh-clients package installed.
Medium Severity
This package includes utilities to make encrypted connections and transfer files securely to SSH servers.
SRG-OS-000023-GPOS-00006
1 Rule
RHEL 9 must display the Standard Mandatory DOD Notice and Consent Banner before granting local or remote access to the system via a SSH logon.
Medium Severity
The warning message reinforces policy awareness during the logon process and facilitates possible legal action against attackers. Alternatively, systems whose ownership should not be obvious should ensure usage of a banner that does not provide easy attribution. Satisfies: SRG-OS-000023-GPOS-00006, SRG-OS-000228-GPOS-00088
SRG-OS-000032-GPOS-00013
1 Rule
RHEL 9 must log SSH connection attempts and failures to the server.
Medium Severity
SSH provides several logging levels with varying amounts of verbosity. "DEBUG" is specifically not recommended other than strictly for debugging SSH communications since it provides so much data that it is difficult to identify important security information. "INFO" or "VERBOSE" level is the basic level that only records login activity of SSH users. In many situations, such as Incident Response, it is important to determine when a particular user was active on a system. The logout record can eliminate those users who disconnected, which helps narrow the field.
SRG-OS-000105-GPOS-00052
1 Rule
RHEL 9 SSHD must accept public key authentication.
Medium Severity
Without the use of multifactor authentication, the ease of access to privileged functions is greatly increased. Multifactor authentication requires using two or more factors to achieve authentication. A privileged account is defined as an information system account with authorizations of a privileged user. A DOD common access card (CAC) with DOD-approved PKI is an example of multifactor authentication. Satisfies: SRG-OS-000105-GPOS-00052, SRG-OS-000106-GPOS-00053, SRG-OS-000107-GPOS-00054, SRG-OS-000108-GPOS-00055
SRG-OS-000106-GPOS-00053
1 Rule
RHEL 9 SSHD must not allow blank passwords.
High Severity
If an account has an empty password, anyone could log on and run commands with the privileges of that account. Accounts with empty passwords should never be used in operational environments. Satisfies: SRG-OS-000106-GPOS-00053, SRG-OS-000480-GPOS-00229, SRG-OS-000480-GPOS-00227
SRG-OS-000109-GPOS-00056
1 Rule
RHEL 9 must not permit direct logons to the root account using remote access via SSH.
Medium Severity
Even though the communications channel may be encrypted, an additional layer of security is gained by extending the policy of not logging directly on as root. In addition, logging in with a user-specific account provides individual accountability of actions performed on the system and also helps to minimize direct attack attempts on root's password. Satisfies: SRG-OS-000109-GPOS-00056, SRG-OS-000480-GPOS-00227
SRG-OS-000125-GPOS-00065
1 Rule
RHEL 9 must enable the Pluggable Authentication Module (PAM) interface for SSHD.
High Severity
When UsePAM is set to "yes", PAM runs through account and session types properly. This is important when restricted access to services based off of IP, time, or other factors of the account is needed. Additionally, this ensures users can inherit certain environment variables on login or disallow access to the server.
SRG-OS-000250-GPOS-00093
1 Rule
RHEL 9 SSH daemon must be configured to use system-wide crypto policies.
Medium Severity
Without cryptographic integrity protections, information can be altered by unauthorized users without detection. Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash.
SRG-OS-000250-GPOS-00093
1 Rule
RHEL 9 must implement DOD-approved encryption ciphers to protect the confidentiality of SSH connections.
Medium Severity
Without cryptographic integrity protections, information can be altered by unauthorized users without detection. Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash. RHEL 9 incorporates systemwide crypto policies by default. The SSH configuration file has no effect on the ciphers, MACs, or algorithms unless specifically defined in the /etc/sysconfig/sshd file. The employed algorithms can be viewed in the /etc/crypto-policies/back-ends/opensshserver.config file.
SRG-OS-000250-GPOS-00093
1 Rule
The RHEL 9 SSH server must be configured to use only DOD-approved encryption ciphers employing FIPS 140-3 validated cryptographic hash algorithms to protect the confidentiality of SSH server connections.
Medium Severity
Without cryptographic integrity protections, information can be altered by unauthorized users without detection. Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash. RHEL 9 incorporates systemwide crypto policies by default. The SSH configuration file has no effect on the ciphers, MACs, or algorithms unless specifically defined in the /etc/sysconfig/sshd file. The employed algorithms can be viewed in the /etc/crypto-policies/back-ends/opensshserver.config file.
SRG-OS-000250-GPOS-00093
1 Rule
The RHEL 9 SSH server must be configured to use only Message Authentication Codes (MACs) employing FIPS 140-3 validated cryptographic hash algorithms to protect the confidentiality of SSH server connections.
Medium Severity
Without cryptographic integrity protections, information can be altered by unauthorized users without detection. Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash. RHEL 9 incorporates systemwide crypto policies by default. The SSH configuration file has no effect on the ciphers, MACs, or algorithms unless specifically defined in the /etc/sysconfig/sshd file. The employed algorithms can be viewed in the /etc/crypto-policies/back-ends/opensshserver.config file.
SRG-OS-000480-GPOS-00229
1 Rule
RHEL 9 must not allow a noncertificate trusted host SSH logon to the system.
Medium Severity
SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts.
SRG-OS-000480-GPOS-00229
1 Rule
RHEL 9 must not allow users to override SSH environment variables.
Medium Severity
SSH environment options potentially allow users to bypass access restriction in some configurations.
SRG-OS-000423-GPOS-00187
1 Rule
RHEL 9 must force a frequent session key renegotiation for SSH connections to the server.
Medium Severity
Without protection of the transmitted information, confidentiality and integrity may be compromised because unprotected communications can be intercepted and either read or altered. This requirement applies to both internal and external networks and all types of information system components from which information can be transmitted (e.g., servers, mobile devices, notebook computers, printers, copiers, scanners, and facsimile machines). Communication paths outside the physical protection of a controlled boundary are exposed to the possibility of interception and modification. Protecting the confidentiality and integrity of organizational information can be accomplished by physical means (e.g., employing physical distribution systems) or by logical means (e.g., employing cryptographic techniques). If physical means of protection are employed, then logical means (cryptography) do not have to be employed, and vice versa. Session key regeneration limits the chances of a session key becoming compromised. Satisfies: SRG-OS-000423-GPOS-00187, SRG-OS-000033-GPOS-00014, SRG-OS-000424-GPOS-00188
SRG-OS-000163-GPOS-00072
1 Rule
RHEL 9 must be configured so that all network connections associated with SSH traffic terminate after becoming unresponsive.
Medium Severity
Terminating an unresponsive SSH session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle SSH session will also free up resources committed by the managed network element. Terminating network connections associated with communications sessions includes, for example, deallocating associated TCP/IP address/port pairs at the operating system level and deallocating networking assignments at the application level if multiple application sessions are using a single operating system-level network connection. This does not mean the operating system terminates all sessions or network access; it only ends the unresponsive session and releases the resources associated with that session. RHEL 9 utilizes /etc/ssh/sshd_config for configurations of OpenSSH. Within the sshd_config, the product of the values of "ClientAliveInterval" and "ClientAliveCountMax" are used to establish the inactivity threshold. The "ClientAliveInterval" is a timeout interval in seconds, after which if no data has been received from the client, sshd will send a message through the encrypted channel to request a response from the client. The "ClientAliveCountMax" is the number of client alive messages that may be sent without sshd receiving any messages back from the client. If this threshold is met, sshd will disconnect the client. For more information on these settings and others, refer to the sshd_config man pages. Satisfies: SRG-OS-000163-GPOS-00072, SRG-OS-000279-GPOS-00109
SRG-OS-000126-GPOS-00066
1 Rule
RHEL 9 must be configured so that all network connections associated with SSH traffic are terminated after 10 minutes of becoming unresponsive.
Medium Severity
Terminating an unresponsive SSH session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle SSH session will also free up resources committed by the managed network element. Terminating network connections associated with communications sessions includes, for example, deallocating associated TCP/IP address/port pairs at the operating system level and deallocating networking assignments at the application level if multiple application sessions are using a single operating system-level network connection. This does not mean the operating system terminates all sessions or network access; it only ends the unresponsive session and releases the resources associated with that session. RHEL 9 utilizes /etc/ssh/sshd_config for configurations of OpenSSH. Within the sshd_config, the product of the values of "ClientAliveInterval" and "ClientAliveCountMax" are used to establish the inactivity threshold. The "ClientAliveInterval" is a timeout interval in seconds, after which if no data has been received from the client, sshd will send a message through the encrypted channel to request a response from the client. The "ClientAliveCountMax" is the number of client alive messages that may be sent without sshd receiving any messages back from the client. If this threshold is met, sshd will disconnect the client. For more information on these settings and others, refer to the sshd_config man pages. Satisfies: SRG-OS-000126-GPOS-00066, SRG-OS-000163-GPOS-00072, SRG-OS-000279-GPOS-00109, SRG-OS-000395-GPOS-00175
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 SSH server configuration file must be group-owned by root.
Medium Severity
Service configuration files enable or disable features of their respective services, which if configured incorrectly, can lead to insecure and vulnerable configurations. Therefore, service configuration files must be owned by the correct group to prevent unauthorized changes.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 SSH server configuration file must be owned by root.
Medium Severity
Service configuration files enable or disable features of their respective services, which if configured incorrectly, can lead to insecure and vulnerable configurations. Therefore, service configuration files must be owned by the correct group to prevent unauthorized changes.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 SSH server configuration file must have mode 0600 or less permissive.
Medium Severity
Service configuration files enable or disable features of their respective services that if configured incorrectly can lead to insecure and vulnerable configurations. Therefore, service configuration files should be owned by the correct group to prevent unauthorized changes.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 SSH private host key files must have mode 0640 or less permissive.
Medium Severity
If an unauthorized user obtains the private SSH host key file, the host could be impersonated.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 SSH public host key files must have mode 0644 or less permissive.
Medium Severity
If a public host key file is modified by an unauthorized user, the SSH service may be compromised.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 SSH daemon must not allow compression or must only allow compression after successful authentication.
Medium Severity
If compression is allowed in an SSH connection prior to authentication, vulnerabilities in the compression software could result in compromise of the system from an unauthenticated connection, potentially with root privileges.
SRG-OS-000364-GPOS-00151
1 Rule
RHEL 9 SSH daemon must not allow GSSAPI authentication.
Medium Severity
Generic Security Service Application Program Interface (GSSAPI) authentication is used to provide additional authentication mechanisms to applications. Allowing GSSAPI authentication through SSH exposes the system's GSSAPI to remote hosts, increasing the attack surface of the system. Satisfies: SRG-OS-000364-GPOS-00151, SRG-OS-000480-GPOS-00227
SRG-OS-000364-GPOS-00151
1 Rule
RHEL 9 SSH daemon must not allow Kerberos authentication.
Medium Severity
Kerberos authentication for SSH is often implemented using Generic Security Service Application Program Interface (GSSAPI). If Kerberos is enabled through SSH, the SSH daemon provides a means of access to the system's Kerberos implementation. Vulnerabilities in the system's Kerberos implementations may be subject to exploitation. Satisfies: SRG-OS-000364-GPOS-00151, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 SSH daemon must not allow rhosts authentication.
Medium Severity
SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 SSH daemon must not allow known hosts authentication.
Medium Severity
Configuring the IgnoreUserKnownHosts setting for the SSH daemon provides additional assurance that remote login via SSH will require a password, even in the event of misconfiguration elsewhere.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 SSH daemon must disable remote X connections for interactive users.
Medium Severity
When X11 forwarding is enabled, there may be additional exposure to the server and client displays if the sshd proxy display is configured to listen on the wildcard address. By default, sshd binds the forwarding server to the loopback address and sets the hostname part of the DISPLAY environment variable to localhost. This prevents remote hosts from connecting to the proxy display.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 SSH daemon must perform strict mode checking of home directory configuration files.
Medium Severity
If other users have access to modify user-specific SSH configuration files, they may be able to log into the system as another user.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 SSH daemon must display the date and time of the last successful account logon upon an SSH logon.
Medium Severity
Providing users feedback on when account accesses last occurred facilitates user recognition and reporting of unauthorized account use.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 SSH daemon must prevent remote hosts from connecting to the proxy display.
Medium Severity
When X11 forwarding is enabled, there may be additional exposure to the server and client displays if the sshd proxy display is configured to listen on the wildcard address. By default, sshd binds the forwarding server to the loopback address and sets the hostname part of the "DISPLAY" environment variable to localhost. This prevents remote hosts from connecting to the proxy display.
SRG-OS-000023-GPOS-00006
1 Rule
RHEL 9 must display the Standard Mandatory DOD Notice and Consent Banner before granting local or remote access to the system via a graphical user logon.
Medium Severity
Display of a standardized and approved use notification before granting access to the operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance. For U.S. Government systems, system use notifications are required only for access via login interfaces with human users and are not required when such human interfaces do not exist. Satisfies: SRG-OS-000023-GPOS-00006, SRG-OS-000228-GPOS-00088
SRG-OS-000023-GPOS-00006
1 Rule
RHEL 9 must prevent a user from overriding the banner-message-enable setting for the graphical user interface.
Medium Severity
Display of a standardized and approved use notification before granting access to the operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance. For U.S. Government systems, system use notifications are required only for access via login interfaces with human users and are not required when such human interfaces do not exist. Satisfies: SRG-OS-000023-GPOS-00006, SRG-OS-000228-GPOS-00088
SRG-OS-000114-GPOS-00059
1 Rule
RHEL 9 must disable the graphical user interface automount function unless required.
Medium Severity
Automatically mounting file systems permits easy introduction of unknown devices, thereby facilitating malicious activity. Satisfies: SRG-OS-000114-GPOS-00059, SRG-OS-000378-GPOS-00163, SRG-OS-000480-GPOS-00227
SRG-OS-000114-GPOS-00059
1 Rule
RHEL 9 must prevent a user from overriding the disabling of the graphical user interface automount function.
Medium Severity
A nonprivileged account is any operating system account with authorizations of a nonprivileged user. Satisfies: SRG-OS-000114-GPOS-00059, SRG-OS-000378-GPOS-00163, SRG-OS-000480-GPOS-00227
SRG-OS-000368-GPOS-00154
1 Rule
RHEL 9 must disable the graphical user interface autorun function unless required.
Medium Severity
Allowing autorun commands to execute may introduce malicious code to a system. Configuring this setting prevents autorun commands from executing.
SRG-OS-000114-GPOS-00059
1 Rule
RHEL 9 must prevent a user from overriding the disabling of the graphical user interface autorun function.
Medium Severity
Techniques used to address this include protocols using nonces (e.g., numbers generated for a specific one-time use) or challenges (e.g., TLS, WS_Security). Additional techniques include time-synchronous or challenge-response one-time authenticators. Satisfies: SRG-OS-000114-GPOS-00059, SRG-OS-000378-GPOS-00163, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00229
1 Rule
RHEL 9 must not allow unattended or automatic logon via the graphical user interface.
High Severity
Failure to restrict system access to authenticated users negatively impacts operating system security.
SRG-OS-000028-GPOS-00009
1 Rule
RHEL 9 must be able to initiate directly a session lock for all connection types using smart card when the smart card is removed.
Medium Severity
A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to log out because of the temporary nature of the absence. The session lock is implemented at the point where session activity can be determined. Rather than be forced to wait for a period of time to expire before the user session can be locked, RHEL 9 needs to provide users with the ability to manually invoke a session lock so users can secure their session if it is necessary to temporarily vacate the immediate physical vicinity. Satisfies: SRG-OS-000028-GPOS-00009, SRG-OS-000030-GPOS-00011
SRG-OS-000028-GPOS-00009
1 Rule
RHEL 9 must prevent a user from overriding the disabling of the graphical user smart card removal action.
Medium Severity
A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to log out because of the temporary nature of the absence. The session lock is implemented at the point where session activity can be determined. Rather than be forced to wait for a period of time to expire before the user session can be locked, RHEL 9 needs to provide users with the ability to manually invoke a session lock so users can secure their session if it is necessary to temporarily vacate the immediate physical vicinity. Satisfies: SRG-OS-000028-GPOS-00009, SRG-OS-000030-GPOS-00011
SRG-OS-000028-GPOS-00009
1 Rule
RHEL 9 must enable a user session lock until that user re-establishes access using established identification and authentication procedures for graphical user sessions.
Medium Severity
A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to log out because of the temporary nature of the absence. The session lock is implemented at the point where session activity can be determined. Regardless of where the session lock is determined and implemented, once invoked, the session lock must remain in place until the user reauthenticates. No other activity aside from reauthentication must unlock the system. Satisfies: SRG-OS-000028-GPOS-00009, SRG-OS-000030-GPOS-00011
SRG-OS-000028-GPOS-00009
1 Rule
RHEL 9 must prevent a user from overriding the screensaver lock-enabled setting for the graphical user interface.
Medium Severity
A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not log out because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, operating systems need to be able to identify when a user's session has idled and take action to initiate the session lock. The session lock is implemented at the point where session activity can be determined and/or controlled. Implementing session settings will have little value if a user is able to manipulate these settings from the defaults prescribed in the other requirements of this implementation guide. Satisfies: SRG-OS-000028-GPOS-00009, SRG-OS-000030-GPOS-00011
SRG-OS-000029-GPOS-00010
1 Rule
RHEL 9 must automatically lock graphical user sessions after 15 minutes of inactivity.
Medium Severity
A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not logout because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, the GNOME desktop can be configured to identify when a user's session has idled and take action to initiate a session lock. Satisfies: SRG-OS-000029-GPOS-00010, SRG-OS-000031-GPOS-00012
SRG-OS-000029-GPOS-00010
1 Rule
RHEL 9 must prevent a user from overriding the session idle-delay setting for the graphical user interface.
Medium Severity
A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not logout because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, the GNOME desktop can be configured to identify when a user's session has idled and take action to initiate the session lock. As such, users should not be allowed to change session settings. Satisfies: SRG-OS-000029-GPOS-00010, SRG-OS-000031-GPOS-00012
SRG-OS-000029-GPOS-00010
1 Rule
RHEL 9 must initiate a session lock for graphical user interfaces when the screensaver is activated.
Medium Severity
A session lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not want to logout because of the temporary nature of the absence.
SRG-OS-000029-GPOS-00010
1 Rule
RHEL 9 must prevent a user from overriding the session lock-delay setting for the graphical user interface.
Medium Severity
A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not logout because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, the GNOME desktop can be configured to identify when a user's session has idled and take action to initiate the session lock. As such, users should not be allowed to change session settings.
SRG-OS-000031-GPOS-00012
1 Rule
RHEL 9 must conceal, via the session lock, information previously visible on the display with a publicly viewable image.
Medium Severity
Setting the screensaver mode to blank-only conceals the contents of the display from passersby.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 effective dconf policy must match the policy keyfiles.
Medium Severity
Unlike text-based keyfiles, the binary database is impossible to check through most automated and all manual means; therefore, in order to evaluate dconf configuration, both have to be true at the same time - configuration files have to be compliant, and the database needs to be more recent than those keyfiles, which gives confidence that it reflects them.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must disable the ability of a user to restart the system from the login screen.
Medium Severity
A user who is at the console can reboot the system at the login screen. If restart or shutdown buttons are pressed at the login screen, this can create the risk of short-term loss of availability of systems due to reboot.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent a user from overriding the disable-restart-buttons setting for the graphical user interface.
Medium Severity
A user who is at the console can reboot the system at the login screen. If restart or shutdown buttons are pressed at the login screen, this can create the risk of short-term loss of availability of systems due to reboot.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must disable the ability of a user to accidentally press Ctrl-Alt-Del and cause a system to shut down or reboot.
Medium Severity
A locally logged-in user who presses Ctrl-Alt-Del, when at the console, can reboot the system. If accidentally pressed, as could happen in the case of mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must prevent a user from overriding the Ctrl-Alt-Del sequence settings for the graphical user interface.
Medium Severity
A locally logged-in user who presses Ctrl-Alt-Del, when at the console, can reboot the system. If accidentally pressed, as could happen in the case of mixed OS environment, this can create the risk of short-term loss of availability of systems due to unintentional reboot.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must disable the user list at logon for graphical user interfaces.
Medium Severity
Leaving the user list enabled is a security risk since it allows anyone with physical access to the system to enumerate known user accounts without authenticated access to the system.
SRG-OS-000114-GPOS-00059
1 Rule
RHEL 9 must be configured to disable USB mass storage.
Medium Severity
USB mass storage permits easy introduction of unknown devices, thereby facilitating malicious activity. Satisfies: SRG-OS-000114-GPOS-00059, SRG-OS-000378-GPOS-00163, SRG-OS-000480-GPOS-00227
SRG-OS-000378-GPOS-00163
1 Rule
RHEL 9 must have the USBGuard package installed.
Medium Severity
The USBguard-daemon is the main component of the USBGuard software framework. It runs as a service in the background and enforces the USB device authorization policy for all USB devices. The policy is defined by a set of rules using a rule language described in the usbguard-rules.conf file. The policy and the authorization state of USB devices can be modified during runtime using the usbguard tool. The system administrator (SA) must work with the site information system security officer (ISSO) to determine a list of authorized peripherals and establish rules within the USBGuard software framework to allow only authorized devices.
SRG-OS-000378-GPOS-00163
1 Rule
RHEL 9 must have the USBGuard package enabled.
Medium Severity
The USBguard-daemon is the main component of the USBGuard software framework. It runs as a service in the background and enforces the USB device authorization policy for all USB devices. The policy is defined by a set of rules using a rule language described in the usbguard-rules.conf file. The policy and the authorization state of USB devices can be modified during runtime using the usbguard tool. The system administrator (SA) must work with the site information system security officer (ISSO) to determine a list of authorized peripherals and establish rules within the USBGuard software framework to allow only authorized devices.
SRG-OS-000062-GPOS-00031
1 Rule
RHEL 9 must enable Linux audit logging for the USBGuard daemon.
Low Severity
Without the capability to generate audit records, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. If auditing is enabled late in the startup process, the actions of some startup processes may not be audited. Some audit systems also maintain state information only available if auditing is enabled before a given process is created. Audit records can be generated from various components within the information system (e.g., module or policy filter). The list of audited events is the set of events for which audits are to be generated. This set of events is typically a subset of the list of all events for which the system is capable of generating audit records. DOD has defined the list of events for which RHEL 9 will provide an audit record generation capability as the following: 1) Successful and unsuccessful attempts to access, modify, or delete privileges, security objects, security levels, or categories of information (e.g., classification levels); 2) Access actions, such as successful and unsuccessful logon attempts, privileged activities or other system-level access, starting and ending time for user access to the system, concurrent logons from different workstations, successful and unsuccessful accesses to objects, all program initiations, and all direct access to the information system; 3) All account creations, modifications, disabling, and terminations; and 4) All kernel module load, unload, and restart actions.
SRG-OS-000378-GPOS-00163
1 Rule
RHEL 9 must block unauthorized peripherals before establishing a connection.
Medium Severity
The USBguard-daemon is the main component of the USBGuard software framework. It runs as a service in the background and enforces the USB device authorization policy for all USB devices. The policy is defined by a set of rules using a rule language described in the usbguard-rules.conf file. The policy and the authorization state of USB devices can be modified during runtime using the usbguard tool. The system administrator (SA) must work with the site information system security officer (ISSO) to determine a list of authorized peripherals and establish rules within the USBGuard software framework to allow only authorized devices.
SRG-OS-000095-GPOS-00049
1 Rule
RHEL 9 Bluetooth must be disabled.
Medium Severity
This requirement applies to wireless peripheral technologies (e.g., wireless mice, keyboards, displays, etc.) used with RHEL 9 systems. Wireless peripherals (e.g., Wi-Fi/Bluetooth/IR keyboards, mice and pointing devices, and near field communications [NFC]) present a unique challenge by creating an open, unsecured port on a computer. Wireless peripherals must meet DOD requirements for wireless data transmission and be approved for use by the Authorizing Official (AO). Even though some wireless peripherals, such as mice and pointing devices, do not ordinarily carry information that need to be protected, modification of communications with these wireless peripherals may be used to compromise the RHEL 9 operating system. Satisfies: SRG-OS-000095-GPOS-00049, SRG-OS-000300-GPOS-00118
SRG-OS-000299-GPOS-00117
1 Rule
RHEL 9 wireless network adapters must be disabled.
Medium Severity
This requirement applies to wireless peripheral technologies (e.g., wireless mice, keyboards, displays, etc.) used with RHEL 9 systems. Wireless peripherals (e.g., Wi-Fi/Bluetooth/IR keyboards, mice and pointing devices, and near field communications [NFC]) present a unique challenge by creating an open, unsecured port on a computer. Wireless peripherals must meet DOD requirements for wireless data transmission and be approved for use by the Authorizing Official (AO). Even though some wireless peripherals, such as mice and pointing devices, do not ordinarily carry information that need to be protected, modification of communications with these wireless peripherals may be used to compromise the RHEL 9 operating system. Satisfies: SRG-OS-000299-GPOS-00117, SRG-OS-000300-GPOS-00118, SRG-OS-000424-GPOS-00188, SRG-OS-000481-GPOS-00481
SRG-OS-000076-GPOS-00044
1 Rule
RHEL 9 user account passwords for new users or password changes must have a 60-day maximum password lifetime restriction in /etc/login.defs.
Medium Severity
Any password, no matter how complex, can eventually be cracked; therefore, passwords need to be changed periodically. If the operating system does not limit the lifetime of passwords and force users to change their passwords, there is the risk that the operating system passwords could be compromised. Setting the password maximum age ensures users are required to periodically change their passwords. Requiring shorter password lifetimes increases the risk of users writing down the password in a convenient location subject to physical compromise.
SRG-OS-000076-GPOS-00044
1 Rule
RHEL 9 user account passwords must have a 60-day maximum password lifetime restriction.
Medium Severity
Any password, no matter how complex, can eventually be cracked; therefore, passwords need to be changed periodically. If RHEL 9 does not limit the lifetime of passwords and force users to change their passwords, there is the risk that RHEL 9 passwords could be compromised.
SRG-OS-000480-GPOS-00227
1 Rule
All RHEL 9 local interactive user accounts must be assigned a home directory upon creation.
Medium Severity
If local interactive users are not assigned a valid home directory, there is no place for the storage and control of files they should own.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must set the umask value to 077 for all local interactive user accounts.
Medium Severity
The umask controls the default access mode assigned to newly created files. A umask of 077 limits new files to mode 600 or less permissive. Although umask can be represented as a four-digit number, the first digit representing special access modes is typically ignored or required to be "0". This requirement applies to the globally configured system defaults and the local interactive user defaults for each account on the system.
SRG-OS-000104-GPOS-00051
1 Rule
RHEL 9 duplicate User IDs (UIDs) must not exist for interactive users.
Medium Severity
To ensure accountability and prevent unauthenticated access, interactive users must be identified and authenticated to prevent potential misuse and compromise of the system. Satisfies: SRG-OS-000104-GPOS-00051, SRG-OS-000121-GPOS-00062, SRG-OS-000042-GPOS-00020
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 system accounts must not have an interactive login shell.
Medium Severity
Ensuring shells are not given to system accounts upon login makes it more difficult for attackers to make use of system accounts.
SRG-OS-000123-GPOS-00064
1 Rule
RHEL 9 must automatically expire temporary accounts within 72 hours.
Medium Severity
Temporary accounts are privileged or nonprivileged accounts that are established during pressing circumstances, such as new software or hardware configuration or an incident response, where the need for prompt account activation requires bypassing normal account authorization procedures. If any inactive temporary accounts are left enabled on the system and are not either manually removed or automatically expired within 72 hours, the security posture of the system will be degraded and exposed to exploitation by unauthorized users or insider threat actors. Temporary accounts are different from emergency accounts. Emergency accounts, also known as "last resort" or "break glass" accounts, are local logon accounts enabled on the system for emergency use by authorized system administrators to manage a system when standard logon methods are failing or not available. Emergency accounts are not subject to manual removal or scheduled expiration requirements. The automatic expiration of temporary accounts may be extended as needed by the circumstances but it must not be extended indefinitely. A documented permanent account should be established for privileged users who need long-term maintenance accounts. Satisfies: SRG-OS-000123-GPOS-00064, SRG-OS-000002-GPOS-00002
SRG-OS-000104-GPOS-00051
1 Rule
All RHEL 9 interactive users must have a primary group that exists.
Medium Severity
If a user is assigned the Group Identifier (GID) of a group that does not exist on the system, and a group with the GID is subsequently created, the user may have unintended rights to any files associated with the group.
SRG-OS-000118-GPOS-00060
1 Rule
RHEL 9 must disable account identifiers (individuals, groups, roles, and devices) after 35 days of inactivity.
Medium Severity
Inactive identifiers pose a risk to systems and applications because attackers may exploit an inactive identifier and potentially obtain undetected access to the system. Disabling inactive accounts ensures that accounts which may not have been responsibly removed are not available to attackers who may have compromised their credentials. Owners of inactive accounts will not notice if unauthorized access to their user account has been obtained.
SRG-OS-000480-GPOS-00227
1 Rule
Executable search paths within the initialization files of all local interactive RHEL 9 users must only contain paths that resolve to the system default or the users home directory.
Medium Severity
The executable search path (typically the PATH environment variable) contains a list of directories for the shell to search to find executables. If this path includes the current working directory (other than the users home directory), executables in these directories may be executed instead of system commands. This variable is formatted as a colon-separated list of directories. If there is an empty entry, such as a leading or trailing colon or two consecutive colons, this is interpreted as the current working directory. If deviations from the default system search path for the local interactive user are required, they must be documented with the information system security officer (ISSO).
SRG-OS-000480-GPOS-00227
1 Rule
All RHEL 9 local interactive users must have a home directory assigned in the /etc/passwd file.
Medium Severity
If local interactive users are not assigned a valid home directory, there is no place for the storage and control of files they should own.
SRG-OS-000480-GPOS-00227
1 Rule
All RHEL 9 local interactive user home directories defined in the /etc/passwd file must exist.
Medium Severity
If a local interactive user has a home directory defined that does not exist, the user may be given access to the / directory as the current working directory upon logon. This could create a denial of service because the user would not be able to access their logon configuration files, and it may give them visibility to system files they normally would not be able to access.
SRG-OS-000480-GPOS-00227
1 Rule
All RHEL 9 local interactive user home directories must be group-owned by the home directory owner's primary group.
Medium Severity
If the Group Identifier (GID) of a local interactive users home directory is not the same as the primary GID of the user, this would allow unauthorized access to the users files, and users that share the same group may not be able to access files that they legitimately should.
SRG-OS-000329-GPOS-00128
1 Rule
RHEL 9 must automatically lock an account when three unsuccessful logon attempts occur.
Medium Severity
By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, otherwise known as brute-force attacks, is reduced. Limits are imposed by locking the account. Satisfies: SRG-OS-000329-GPOS-00128, SRG-OS-000021-GPOS-00005
SRG-OS-000329-GPOS-00128
1 Rule
RHEL 9 must automatically lock the root account until the root account is released by an administrator when three unsuccessful logon attempts occur during a 15-minute time period.
Medium Severity
By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, also known as brute-forcing, is reduced. Limits are imposed by locking the account. Satisfies: SRG-OS-000329-GPOS-00128, SRG-OS-000021-GPOS-00005
SRG-OS-000329-GPOS-00128
1 Rule
RHEL 9 must automatically lock an account when three unsuccessful logon attempts occur during a 15-minute time period.
Medium Severity
By limiting the number of failed logon attempts the risk of unauthorized system access via user password guessing, otherwise known as brute-forcing, is reduced. Limits are imposed by locking the account. Satisfies: SRG-OS-000329-GPOS-00128, SRG-OS-000021-GPOS-00005
SRG-OS-000329-GPOS-00128
1 Rule
RHEL 9 must maintain an account lock until the locked account is released by an administrator.
Medium Severity
By limiting the number of failed logon attempts the risk of unauthorized system access via user password guessing, otherwise known as brute-forcing, is reduced. Limits are imposed by locking the account. Satisfies: SRG-OS-000329-GPOS-00128, SRG-OS-000021-GPOS-00005
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not have unauthorized accounts.
Medium Severity
Accounts providing no operational purpose provide additional opportunities for system compromise. Unnecessary accounts include user accounts for individuals not requiring access to the system and application accounts for applications not installed on the system.
SRG-OS-000480-GPOS-00227
1 Rule
The root account must be the only account having unrestricted access to RHEL 9 system.
High Severity
An account has root authority if it has a user identifier (UID) of "0". Multiple accounts with a UID of "0" afford more opportunity for potential intruders to guess a password for a privileged account. Proper configuration of sudo is recommended to afford multiple system administrators access to root privileges in an accountable manner.
SRG-OS-000021-GPOS-00005
1 Rule
RHEL 9 must ensure account lockouts persist.
Medium Severity
Having lockouts persist across reboots ensures that account is only unlocked by an administrator. If the lockouts did not persist across reboots, an attacker could simply reboot the system to continue brute force attacks against the accounts on the system.
SRG-OS-000104-GPOS-00051
1 Rule
RHEL 9 groups must have unique Group ID (GID).
Medium Severity
To ensure accountability and prevent unauthenticated access, groups must be identified uniquely to prevent potential misuse and compromise of the system.
SRG-OS-000480-GPOS-00227
1 Rule
Local RHEL 9 initialization files must not execute world-writable programs.
Medium Severity
If user start-up files execute world-writable programs, especially in unprotected directories, they could be maliciously modified to destroy user files or otherwise compromise the system at the user level. If the system is compromised at the user level, it is easier to elevate privileges to eventually compromise the system at the root and network level.
SRG-OS-000163-GPOS-00072
1 Rule
RHEL 9 must automatically exit interactive command shell user sessions after 15 minutes of inactivity.
Medium Severity
Terminating an idle interactive command shell user session within a short time period reduces the window of opportunity for unauthorized personnel to take control of it when left unattended in a virtual terminal or physical console. Satisfies: SRG-OS-000163-GPOS-00072, SRG-OS-000029-GPOS-00010
SRG-OS-000027-GPOS-00008
1 Rule
RHEL 9 must limit the number of concurrent sessions to ten for all accounts and/or account types.
Low Severity
Operating system management includes the ability to control the number of users and user sessions that utilize an operating system. Limiting the number of allowed users and sessions per user is helpful in reducing the risks related to denial-of-service (DoS) attacks. This requirement addresses concurrent sessions for information system accounts and does not address concurrent sessions by single users via multiple system accounts. The maximum number of concurrent sessions must be defined based on mission needs and the operational environment for each system.
SRG-OS-000021-GPOS-00005
1 Rule
RHEL 9 must log username information when unsuccessful logon attempts occur.
Medium Severity
Without auditing of these events, it may be harder or impossible to identify what an attacker did after an attack.
SRG-OS-000480-GPOS-00226
1 Rule
RHEL 9 must enforce a delay of at least four seconds between logon prompts following a failed logon attempt.
Medium Severity
Increasing the time between a failed authentication attempt and reprompting to enter credentials helps to slow a single-threaded brute force attack.
SRG-OS-000480-GPOS-00228
1 Rule
RHEL 9 must define default permissions for the bash shell.
Medium Severity
The umask controls the default access mode assigned to newly created files. A umask of 077 limits new files to mode 600 or less permissive. Although umask can be represented as a four-digit number, the first digit representing special access modes is typically ignored or required to be "0". This requirement applies to the globally configured system defaults and the local interactive user defaults for each account on the system. Satisfies: SRG-OS-000480-GPOS-00228, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00228
1 Rule
RHEL 9 must define default permissions for the c shell.
Medium Severity
The umask controls the default access mode assigned to newly created files. A umask of 077 limits new files to mode 600 or less permissive. Although umask can be represented as a four-digit number, the first digit representing special access modes is typically ignored or required to be "0". This requirement applies to the globally configured system defaults and the local interactive user defaults for each account on the system. Satisfies: SRG-OS-000480-GPOS-00228, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00228
1 Rule
RHEL 9 must define default permissions for all authenticated users in such a way that the user can only read and modify their own files.
Medium Severity
Setting the most restrictive default permissions ensures that when new accounts are created, they do not have unnecessary access.
SRG-OS-000480-GPOS-00228
1 Rule
RHEL 9 must define default permissions for the system default profile.
Medium Severity
The umask controls the default access mode assigned to newly created files. A umask of 077 limits new files to mode 600 or less permissive. Although umask can be represented as a four-digit number, the first digit representing special access modes is typically ignored or required to be "0". This requirement applies to the globally configured system defaults and the local interactive user defaults for each account on the system. Satisfies: SRG-OS-000480-GPOS-00228, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must display the date and time of the last successful account logon upon logon.
Low Severity
Users need to be aware of activity that occurs regarding their account. Providing users with information regarding the number of unsuccessful attempts that were made to login to their account allows the user to determine if any unauthorized activity has occurred and gives them an opportunity to notify administrators.
SRG-OS-000163-GPOS-00072
1 Rule
RHEL 9 must terminate idle user sessions.
Medium Severity
Terminating an idle session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended.
SRG-OS-000445-GPOS-00199
1 Rule
RHEL 9 must use a Linux Security Module configured to enforce limits on system services.
High Severity
Without verification of the security functions, security functions may not operate correctly and the failure may go unnoticed. Security function is defined as the hardware, software, and/or firmware of the information system responsible for enforcing the system security policy and supporting the isolation of code and data on which the protection is based. Security functionality includes, but is not limited to, establishing system accounts, configuring access authorizations (i.e., permissions, privileges), setting events to be audited, and setting intrusion detection parameters. This requirement applies to operating systems performing security function verification/testing and/or systems and environments that require this functionality. Satisfies: SRG-OS-000445-GPOS-00199, SRG-OS-000134-GPOS-00068
SRG-OS-000445-GPOS-00199
1 Rule
RHEL 9 must enable the SELinux targeted policy.
Medium Severity
Setting the SELinux policy to "targeted" or a more specialized policy ensures the system will confine processes that are likely to be targeted for exploitation, such as network or system services. Note: During the development or debugging of SELinux modules, it is common to temporarily place nonproduction systems in "permissive" mode. In such temporary cases, SELinux policies should be developed, and once work is completed, the system should be reconfigured to "targeted".
SRG-OS-000021-GPOS-00005
1 Rule
RHEL 9 must configure SELinux context type to allow the use of a nondefault faillock tally directory.
Medium Severity
Not having the correct SELinux context on the faillock directory may lead to unauthorized access to the directory.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must have policycoreutils package installed.
Medium Severity
Without verification of the security functions, security functions may not operate correctly and the failure may go unnoticed. Security function is defined as the hardware, software, and/or firmware of the information system responsible for enforcing the system security policy and supporting the isolation of code and data on which the protection is based. Security functionality includes, but is not limited to, establishing system accounts, configuring access authorizations (i.e., permissions, privileges), setting events to be audited, and setting intrusion detection parameters. Policycoreutils contains the policy core utilities that are required for basic operation of an SELinux-enabled system. These utilities include load_policy to load SELinux policies, setfile to label filesystems, newrole to switch roles, and run_init to run /etc/init.d scripts in the proper context. Satisfies: SRG-OS-000480-GPOS-00227, SRG-OS-000134-GPOS-00068
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 policycoreutils-python-utils package must be installed.
Medium Severity
The policycoreutils-python-utils package is required to operate and manage an SELinux environment and its policies. It provides utilities such as semanage, audit2allow, audit2why, chcat, and sandbox.
SRG-OS-000324-GPOS-00125
1 Rule
RHEL 9 must have the sudo package installed.
Medium Severity
"sudo" is a program designed to allow a system administrator to give limited root privileges to users and log root activity. The basic philosophy is to give as few privileges as possible but still allow system users to get their work done.
SRG-OS-000373-GPOS-00156
1 Rule
RHEL 9 must require reauthentication when using the "sudo" command.
Medium Severity
Without reauthentication, users may access resources or perform tasks for which they do not have authorization. When operating systems provide the capability to escalate a functional capability, it is critical the organization requires the user to reauthenticate when using the "sudo" command. If the value is set to an integer less than "0", the user's time stamp will not expire and the user will not have to reauthenticate for privileged actions until the user's session is terminated.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must use the invoking user's password for privilege escalation when using "sudo".
Medium Severity
If the rootpw, targetpw, or runaspw flags are defined and not disabled, by default the operating system will prompt the invoking user for the "root" user password.
SRG-OS-000373-GPOS-00156
1 Rule
RHEL 9 must require users to reauthenticate for privilege escalation.
Medium Severity
Without reauthentication, users may access resources or perform tasks for which they do not have authorization. When operating systems provide the capability to escalate a functional capability, it is critical that the user reauthenticate. Satisfies: SRG-OS-000373-GPOS-00156, SRG-OS-000373-GPOS-00157, SRG-OS-000373-GPOS-00158
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must restrict privilege elevation to authorized personnel.
Medium Severity
If the "sudoers" file is not configured correctly, any user defined on the system can initiate privileged actions on the target system.
SRG-OS-000373-GPOS-00156
1 Rule
RHEL 9 must restrict the use of the "su" command.
Medium Severity
The "su" program allows to run commands with a substitute user and group ID. It is commonly used to run commands as the root user. Limiting access to such commands is considered a good security practice. Satisfies: SRG-OS-000373-GPOS-00156, SRG-OS-000312-GPOS-00123
SRG-OS-000370-GPOS-00155
1 Rule
RHEL 9 fapolicy module must be installed.
Medium Severity
The organization must identify authorized software programs and permit execution of authorized software. The process used to identify software programs that are authorized to execute on organizational information systems is commonly referred to as allow listing. Utilizing an allow list provides a configuration management method for allowing the execution of only authorized software. Using only authorized software decreases risk by limiting the number of potential vulnerabilities. Verification of allow listed software occurs prior to execution or at system startup. User home directories/folders may contain information of a sensitive nature. Nonprivileged users should coordinate any sharing of information with an SA through shared resources. RHEL 9 ships with many optional packages. One such package is a file access policy daemon called "fapolicyd". "fapolicyd" is a userspace daemon that determines access rights to files based on attributes of the process and file. It can be used to either blocklist or allow list processes or file access. Proceed with caution with enforcing the use of this daemon. Improper configuration may render the system nonfunctional. The "fapolicyd" API is not namespace aware and can cause issues when launching or running containers. Satisfies: SRG-OS-000370-GPOS-00155, SRG-OS-000368-GPOS-00154
SRG-OS-000370-GPOS-00155
1 Rule
RHEL 9 fapolicy module must be enabled.
Medium Severity
The organization must identify authorized software programs and permit execution of authorized software. The process used to identify software programs that are authorized to execute on organizational information systems is commonly referred to as allowlisting. Utilizing an allowlist provides a configuration management method for allowing the execution of only authorized software. Using only authorized software decreases risk by limiting the number of potential vulnerabilities. Verification of allowlisted software occurs prior to execution or at system startup. User home directories/folders may contain information of a sensitive nature. Nonprivileged users should coordinate any sharing of information with an SA through shared resources. RHEL 9 ships with many optional packages. One such package is a file access policy daemon called "fapolicyd". "fapolicyd" is a userspace daemon that determines access rights to files based on attributes of the process and file. It can be used to either blocklist or allowlist processes or file access. Proceed with caution with enforcing the use of this daemon. Improper configuration may render the system nonfunctional. The "fapolicyd" API is not namespace aware and can cause issues when launching or running containers. Satisfies: SRG-OS-000370-GPOS-00155, SRG-OS-000368-GPOS-00154
SRG-OS-000069-GPOS-00037
1 Rule
RHEL 9 must ensure the password complexity module in the system-auth file is configured for three retries or less.
Medium Severity
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. "pwquality" enforces complex password construction configuration and has the ability to limit brute-force attacks on the system. RHEL 9 uses "pwquality" as a mechanism to enforce password complexity. This is set in both: /etc/pam.d/password-auth /etc/pam.d/system-auth By limiting the number of attempts to meet the pwquality module complexity requirements before returning with an error, the system will audit abnormal attempts at password changes.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not allow blank or null passwords.
High Severity
If an account has an empty password, anyone could log in and run commands with the privileges of that account. Accounts with empty passwords should never be used in operational environments.
SRG-OS-000021-GPOS-00005
1 Rule
RHEL 9 must configure the use of the pam_faillock.so module in the /etc/pam.d/system-auth file.
Medium Severity
If the pam_faillock.so module is not loaded, the system will not correctly lockout accounts to prevent password guessing attacks.
SRG-OS-000021-GPOS-00005
1 Rule
RHEL 9 must configure the use of the pam_faillock.so module in the /etc/pam.d/password-auth file.
Medium Severity
If the pam_faillock.so module is not loaded, the system will not correctly lockout accounts to prevent password guessing attacks.
SRG-OS-000069-GPOS-00037
1 Rule
RHEL 9 must ensure the password complexity module is enabled in the password-auth file.
Medium Severity
Enabling PAM password complexity permits enforcement of strong passwords and consequently makes the system less prone to dictionary attacks. Satisfies: SRG-OS-000069-GPOS-00037, SRG-OS-000070-GPOS-00038, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must ensure the password complexity module is enabled in the system-auth file.
Medium Severity
Enabling PAM password complexity permits enforcement of strong passwords and consequently makes the system less prone to dictionary attacks.
SRG-OS-000073-GPOS-00041
1 Rule
RHEL 9 password-auth must be configured to use a sufficient number of hashing rounds.
Medium Severity
Passwords need to be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised. Passwords that are encrypted with a weak algorithm are no more protected than if they are kept in plain text. Using more hashing rounds makes password cracking attacks more difficult. Satisfies: SRG-OS-000073-GPOS-00041, SRG-OS-000120-GPOS-00061
SRG-OS-000073-GPOS-00041
1 Rule
RHEL 9 system-auth must be configured to use a sufficient number of hashing rounds.
Medium Severity
Passwords need to be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised. Passwords that are encrypted with a weak algorithm are no more protected than if they are kept in plain text. Using more hashing rounds makes password cracking attacks more difficult. Satisfies: SRG-OS-000073-GPOS-00041, SRG-OS-000120-GPOS-00061
SRG-OS-000072-GPOS-00040
1 Rule
RHEL 9 must enforce password complexity rules for the root account.
Medium Severity
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. Satisfies: SRG-OS-000072-GPOS-00040, SRG-OS-000071-GPOS-00039, SRG-OS-000070-GPOS-00038, SRG-OS-000266-GPOS-00101, SRG-OS-000078-GPOS-00046, SRG-OS-000480-GPOS-00225, SRG-OS-000069-GPOS-00037
SRG-OS-000070-GPOS-00038
1 Rule
RHEL 9 must enforce password complexity by requiring that at least one lowercase character be used.
Medium Severity
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. Requiring a minimum number of lowercase characters makes password guessing attacks more difficult by ensuring a larger search space.
SRG-OS-000071-GPOS-00039
1 Rule
RHEL 9 must enforce password complexity by requiring that at least one numeric character be used.
Medium Severity
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. Requiring digits makes password guessing attacks more difficult by ensuring a larger search space.
SRG-OS-000075-GPOS-00043
1 Rule
RHEL 9 passwords for new users or password changes must have a 24 hours minimum password lifetime restriction in /etc/login.defs.
Medium Severity
Enforcing a minimum password lifetime helps to prevent repeated password changes to defeat the password reuse or history enforcement requirement. If users are allowed to immediately and continually change their password, then the password could be repeatedly changed in a short period of time to defeat the organization's policy regarding password reuse. Setting the minimum password age protects against users cycling back to a favorite password after satisfying the password reuse requirement.
SRG-OS-000075-GPOS-00043
1 Rule
RHEL 9 passwords must have a 24 hours minimum password lifetime restriction in /etc/shadow.
Medium Severity
Enforcing a minimum password lifetime helps to prevent repeated password changes to defeat the password reuse or history enforcement requirement. If users are allowed to immediately and continually change their password, the password could be repeatedly changed in a short period of time to defeat the organization's policy regarding password reuse.
SRG-OS-000373-GPOS-00156
1 Rule
RHEL 9 must require users to provide a password for privilege escalation.
Medium Severity
Without reauthentication, users may access resources or perform tasks for which they do not have authorization. When operating systems provide the capability to escalate a functional capability, it is critical that the user reauthenticate. Satisfies: SRG-OS-000373-GPOS-00156, SRG-OS-000373-GPOS-00157, SRG-OS-000373-GPOS-00158
SRG-OS-000078-GPOS-00046
1 Rule
RHEL 9 passwords must be created with a minimum of 15 characters.
Medium Severity
The shorter the password, the lower the number of possible combinations that need to be tested before the password is compromised. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password length is one factor of several that helps to determine strength and how long it takes to crack a password. Use of more characters in a password helps to increase exponentially the time and/or resources required to compromise the password. RHEL 9 uses "pwquality" as a mechanism to enforce password complexity. Configurations are set in the "etc/security/pwquality.conf" file. The "minlen", sometimes noted as minimum length, acts as a "score" of complexity based on the credit components of the "pwquality" module. By setting the credit components to a negative value, not only will those components be required, but they will not count toward the total "score" of "minlen". This will enable "minlen" to require a 15-character minimum. The DOD minimum password requirement is 15 characters.
SRG-OS-000266-GPOS-00101
1 Rule
RHEL 9 must enforce password complexity by requiring that at least one special character be used.
Medium Severity
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. RHEL 9 utilizes "pwquality" as a mechanism to enforce password complexity. Note that to require special characters without degrading the "minlen" value, the credit value must be expressed as a negative number in "/etc/security/pwquality.conf".
SRG-OS-000480-GPOS-00225
1 Rule
RHEL 9 must prevent the use of dictionary words for passwords.
Medium Severity
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. If RHEL 9 allows the user to select passwords based on dictionary words, this increases the chances of password compromise by increasing the opportunity for successful guesses, and brute-force attacks.
SRG-OS-000069-GPOS-00037
1 Rule
RHEL 9 must enforce password complexity by requiring that at least one uppercase character be used.
Medium Severity
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. Requiring a minimum number of uppercase characters makes password guessing attacks more difficult by ensuring a larger search space.
SRG-OS-000072-GPOS-00040
1 Rule
RHEL 9 must require the change of at least eight characters when passwords are changed.
Medium Severity
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor of several that determines how long it takes to crack a password. The more complex the password, the greater the number of possible combinations that need to be tested before the password is compromised. Requiring a minimum number of different characters during password changes ensures that newly changed passwords will not resemble previously compromised ones. Note that passwords changed on compromised systems will still be compromised.
SRG-OS-000072-GPOS-00040
1 Rule
RHEL 9 must require the maximum number of repeating characters of the same character class be limited to four when passwords are changed.
Medium Severity
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor of several that determines how long it takes to crack a password. The more complex a password, the greater the number of possible combinations that need to be tested before the password is compromised.
SRG-OS-000072-GPOS-00040
1 Rule
RHEL 9 must require the maximum number of repeating characters be limited to three when passwords are changed.
Medium Severity
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor of several that determines how long it takes to crack a password. The more complex a password, the greater the number of possible combinations that need to be tested before the password is compromised.
SRG-OS-000072-GPOS-00040
1 Rule
RHEL 9 must require the change of at least four character classes when passwords are changed.
Medium Severity
Use of a complex password helps to increase the time and resources required to compromise the password. Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. Password complexity is one factor of several that determines how long it takes to crack a password. The more complex a password, the greater the number of possible combinations that need to be tested before the password is compromised.
SRG-OS-000073-GPOS-00041
1 Rule
RHEL 9 must be configured so that user and group account administration utilities are configured to store only encrypted representations of passwords.
Medium Severity
Passwords need to be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised. Passwords that are encrypted with a weak algorithm are no more protected than if they are kept in plain text. This setting ensures user and group account administration utilities are configured to store only encrypted representations of passwords. Additionally, the "crypt_style" configuration option ensures the use of a strong hashing algorithm that makes password cracking attacks more difficult.
SRG-OS-000073-GPOS-00041
1 Rule
RHEL 9 must be configured to use the shadow file to store only encrypted representations of passwords.
Medium Severity
Passwords need to be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised. Passwords that are encrypted with a weak algorithm are no more protected than if they are kept in plain text. This setting ensures user and group account administration utilities are configured to store only encrypted representations of passwords. Additionally, the "crypt_style" configuration option ensures the use of a strong hashing algorithm that makes password cracking attacks more difficult.
SRG-OS-000373-GPOS-00156
1 Rule
RHEL 9 must not be configured to bypass password requirements for privilege escalation.
Medium Severity
Without reauthentication, users may access resources or perform tasks for which they do not have authorization. When operating systems provide the capability to escalate a functional capability, it is critical the user reauthenticate. Satisfies: SRG-OS-000373-GPOS-00156, SRG-OS-000373-GPOS-00157, SRG-OS-000373-GPOS-00158
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must not have accounts configured with blank or null passwords.
Medium Severity
If an account has an empty password, anyone could log in and run commands with the privileges of that account. Accounts with empty passwords should never be used in operational environments.
SRG-OS-000104-GPOS-00051
1 Rule
RHEL 9 must use the common access card (CAC) smart card driver.
Medium Severity
Smart card login provides two-factor authentication stronger than that provided by a username and password combination. Smart cards leverage public key infrastructure to provide and verify credentials. Configuring the smart card driver in use by the organization helps to prevent users from using unauthorized smart cards. Satisfies: SRG-OS-000104-GPOS-00051, SRG-OS-000106-GPOS-00053, SRG-OS-000107-GPOS-00054, SRG-OS-000109-GPOS-00056, SRG-OS-000108-GPOS-00055, SRG-OS-000112-GPOS-00057, SRG-OS-000113-GPOS-00058
SRG-OS-000375-GPOS-00160
1 Rule
RHEL 9 must enable certificate based smart card authentication.
Medium Severity
Without the use of multifactor authentication, the ease of access to privileged functions is greatly increased. Multifactor authentication requires using two or more factors to achieve authentication. A privileged account is defined as an information system account with authorizations of a privileged user. The DOD Common Access Card (CAC) with DOD-approved PKI is an example of multifactor authentication. Satisfies: SRG-OS-000375-GPOS-00160, SRG-OS-000105-GPOS-00052
SRG-OS-000375-GPOS-00160
1 Rule
RHEL 9 must implement certificate status checking for multifactor authentication.
Medium Severity
Using an authentication device, such as a DOD common access card (CAC) or token that is separate from the information system, ensures that even if the information system is compromised, credentials stored on the authentication device will not be affected. Multifactor solutions that require devices separate from information systems gaining access include, for example, hardware tokens providing time-based or challenge-response authenticators and smart cards such as the U.S. Government Personal Identity Verification (PIV) card and the DOD CAC. RHEL 9 includes multiple options for configuring certificate status checking, but for this requirement focuses on the System Security Services Daemon (SSSD). By default, SSSD performs Online Certificate Status Protocol (OCSP) checking and certificate verification using a sha256 digest function. Satisfies: SRG-OS-000375-GPOS-00160, SRG-OS-000377-GPOS-00162
SRG-OS-000375-GPOS-00160
1 Rule
RHEL 9 must have the pcsc-lite package installed.
Medium Severity
The pcsc-lite package must be installed if it is to be available for multifactor authentication using smart cards.
SRG-OS-000375-GPOS-00160
1 Rule
The pcscd service on RHEL 9 must be active.
Medium Severity
The information system ensures that even if the information system is compromised, that compromise will not affect credentials stored on the authentication device. The daemon program for pcsc-lite and the MuscleCard framework is pcscd. It is a resource manager that coordinates communications with smart card readers and smart cards and cryptographic tokens that are connected to the system.
SRG-OS-000375-GPOS-00160
1 Rule
RHEL 9 must have the opensc package installed.
Medium Severity
The use of PIV credentials facilitates standardization and reduces the risk of unauthorized access. The DOD has mandated the use of the common access card (CAC) to support identity management and personal authentication for systems covered under Homeland Security Presidential Directive (HSPD) 12, as well as making the CAC a primary component of layered protection for national security systems. Satisfies: SRG-OS-000375-GPOS-00160, SRG-OS-000376-GPOS-00161
SRG-OS-000067-GPOS-00035
1 Rule
RHEL 9, for PKI-based authentication, must enforce authorized access to the corresponding private key.
Medium Severity
If the private key is discovered, an attacker can use the key to authenticate as an authorized user and gain access to the network infrastructure. The cornerstone of the PKI is the private key used to encrypt or digitally sign information. If the private key is stolen, this will lead to the compromise of the authentication and nonrepudiation gained through PKI because the attacker can use the private key to digitally sign documents and pretend to be the authorized user. Both the holders of a digital certificate and the issuing authority must protect the computers, storage devices, or whatever they use to keep the private keys.
SRG-OS-000080-GPOS-00048
1 Rule
RHEL 9 must require authentication to access emergency mode.
Medium Severity
To mitigate the risk of unauthorized access to sensitive information by entities that have been issued certificates by DOD-approved PKIs, all DOD systems (e.g., web servers and web portals) must be properly configured to incorporate access control methods that do not rely solely on the possession of a certificate for access. Successful authentication must not automatically give an entity access to an asset or security boundary. Authorization procedures and controls must be implemented to ensure each authenticated entity also has a validated and current authorization. Authorization is the process of determining whether an entity, once authenticated, is permitted to access a specific asset. Information systems use access control policies and enforcement mechanisms to implement this requirement. This requirement prevents attackers with physical access from trivially bypassing security on the machine and gaining root access. Such accesses are further prevented by configuring the bootloader password.
SRG-OS-000080-GPOS-00048
1 Rule
RHEL 9 must require authentication to access single-user mode.
Medium Severity
To mitigate the risk of unauthorized access to sensitive information by entities that have been issued certificates by DOD-approved PKIs, all DOD systems (e.g., web servers and web portals) must be properly configured to incorporate access control methods that do not rely solely on the possession of a certificate for access. Successful authentication must not automatically give an entity access to an asset or security boundary. Authorization procedures and controls must be implemented to ensure each authenticated entity also has a validated and current authorization. Authorization is the process of determining whether an entity, once authenticated, is permitted to access a specific asset. Information systems use access control policies and enforcement mechanisms to implement this requirement. This requirement prevents attackers with physical access from trivially bypassing security on the machine and gaining root access. Such accesses are further prevented by configuring the bootloader password.
SRG-OS-000120-GPOS-00061
1 Rule
RHEL 9 must prevent system daemons from using Kerberos for authentication.
Medium Severity
Unapproved mechanisms used for authentication to the cryptographic module are not verified; therefore, cannot be relied upon to provide confidentiality or integrity and DOD data may be compromised. RHEL 9 systems utilizing encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules. The key derivation function (KDF) in Kerberos is not FIPS compatible. Ensuring the system does not have any keytab files present prevents system daemons from using Kerberos for authentication. A keytab is a file containing pairs of Kerberos principals and encrypted keys. FIPS 140-3 is the current standard for validating that mechanisms used to access cryptographic modules utilize authentication that meets DOD requirements. This allows for Security Levels 1, 2, 3, or 4 for use on a general-purpose computing system.
SRG-OS-000066-GPOS-00034
1 Rule
RHEL 9, for PKI-based authentication, must validate certificates by constructing a certification path (which includes status information) to an accepted trust anchor.
Medium Severity
Without path validation, an informed trust decision by the relying party cannot be made when presented with any certificate not already explicitly trusted. A trust anchor is an authoritative entity represented via a public key and associated data. It is used in the context of public key infrastructures, X.509 digital certificates, and DNSSEC. When there is a chain of trust, usually the top entity to be trusted becomes the trust anchor; it can be, for example, a certification authority (CA). A certification path starts with the subject certificate and proceeds through a number of intermediate certificates up to a trusted root certificate, typically issued by a trusted CA. This requirement verifies that a certification path to an accepted trust anchor is used for certificate validation and that the path includes status information. Path validation is necessary for a relying party to make an informed trust decision when presented with any certificate not already explicitly trusted. Status information for certification paths includes certificate revocation lists or online certificate status protocol responses. Validation of the certificate status information is out of scope for this requirement. Satisfies: SRG-OS-000066-GPOS-00034, SRG-OS-000384-GPOS-00167
SRG-OS-000068-GPOS-00036
1 Rule
RHEL 9 must map the authenticated identity to the user or group account for PKI-based authentication.
Medium Severity
Without mapping the certificate used to authenticate to the user account, the ability to determine the identity of the individual user or group will not be available for forensic analysis.
SRG-OS-000383-GPOS-00166
1 Rule
RHEL 9 must prohibit the use of cached authenticators after one day.
Medium Severity
If cached authentication information is out-of-date, the validity of the authentication information may be questionable.
SRG-OS-000363-GPOS-00150
1 Rule
RHEL 9 must have the AIDE package installed.
Medium Severity
Without verification of the security functions, security functions may not operate correctly, and the failure may go unnoticed. Security function is defined as the hardware, software, and/or firmware of the information system responsible for enforcing the system security policy and supporting the isolation of code and data on which the protection is based. Security functionality includes, but is not limited to, establishing system accounts, configuring access authorizations (i.e., permissions, privileges), setting events to be audited, and setting intrusion detection parameters. Satisfies: SRG-OS-000363-GPOS-00150, SRG-OS-000445-GPOS-00199
SRG-OS-000363-GPOS-00150
1 Rule
RHEL 9 must routinely check the baseline configuration for unauthorized changes and notify the system administrator when anomalies in the operation of any security functions are discovered.
Medium Severity
Unauthorized changes to the baseline configuration could make the system vulnerable to various attacks or allow unauthorized access to the operating system. Changes to operating system configurations can have unintended side effects, some of which may be relevant to security. Detecting such changes and providing an automated response can help avoid unintended, negative consequences that could ultimately affect the security state of the operating system. The operating system's information management officer (IMO)/information system security officer (ISSO) and system administrators (SAs) must be notified via email and/or monitoring system trap when there is an unauthorized modification of a configuration item. Notifications provided by information systems include messages to local computer consoles, and/or hardware indications, such as lights. This capability must take into account operational requirements for availability for selecting an appropriate response. The organization may choose to shut down or restart the information system upon security function anomaly detection. Satisfies: SRG-OS-000363-GPOS-00150, SRG-OS-000446-GPOS-00200, SRG-OS-000447-GPOS-00201
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must use a file integrity tool that is configured to use FIPS 140-3-approved cryptographic hashes for validating file contents and directories.
Medium Severity
RHEL 9 installation media ships with an optional file integrity tool called Advanced Intrusion Detection Environment (AIDE). AIDE is highly configurable at install time. This requirement assumes the "aide.conf" file is under the "/etc" directory. File integrity tools use cryptographic hashes for verifying file contents and directories have not been altered. These hashes must be FIPS 140-3-approved cryptographic hashes.
SRG-OS-000256-GPOS-00097
1 Rule
RHEL 9 must use cryptographic mechanisms to protect the integrity of audit tools.
Medium Severity
Protecting the integrity of the tools used for auditing purposes is a critical step toward ensuring the integrity of audit information. Audit information includes all information (e.g., audit records, audit settings, and audit reports) needed to successfully audit information system activity. Audit tools include, but are not limited to, vendor-provided and open-source audit tools needed to successfully view and manipulate audit information system activity and records. Audit tools include custom queries and report generators. It is not uncommon for attackers to replace the audit tools or inject code into the existing tools to provide the capability to hide or erase system activity from the audit logs. To address this risk, audit tools must be cryptographically signed to provide the capability to identify when the audit tools have been modified, manipulated, or replaced. An example is a checksum hash of the file or files. Satisfies: SRG-OS-000256-GPOS-00097, SRG-OS-000257-GPOS-00098, SRG-OS-000258-GPOS-00099, SRG-OS-000278-GPOS-00108
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must be configured so that the file integrity tool verifies Access Control Lists (ACLs).
Low Severity
RHEL 9 installation media ships with an optional file integrity tool called Advanced Intrusion Detection Environment (AIDE). AIDE is highly configurable at install time. This requirement assumes the "aide.conf" file is under the "/etc" directory. ACLs can provide permissions beyond those permitted through the file mode and must be verified by the file integrity tools.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must be configured so that the file integrity tool verifies extended attributes.
Low Severity
RHEL 9 installation media ships with an optional file integrity tool called Advanced Intrusion Detection Environment (AIDE). AIDE is highly configurable at install time. This requirement assumes the "aide.conf" file is under the "/etc" directory. Extended attributes in file systems are used to contain arbitrary data and file metadata with security implications.
SRG-OS-000479-GPOS-00224
1 Rule
RHEL 9 must have the rsyslog package installed.
Medium Severity
rsyslogd is a system utility providing support for message logging. Support for both internet and Unix domain sockets enables this utility to support both local and remote logging. Couple this utility with "gnutls" (which is a secure communications library implementing the SSL, TLS, and DTLS protocols), to create a method to securely encrypt and offload auditing. Satisfies: SRG-OS-000479-GPOS-00224, SRG-OS-000051-GPOS-00024, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must have the packages required for encrypting offloaded audit logs installed.
Medium Severity
The rsyslog-gnutls package provides Transport Layer Security (TLS) support for the rsyslog daemon, which enables secure remote logging. Satisfies: SRG-OS-000480-GPOS-00227, SRG-OS-000120-GPOS-00061
SRG-OS-000480-GPOS-00227
1 Rule
The rsyslog service on RHEL 9 must be active.
Medium Severity
The "rsyslog" service must be running to provide logging services, which are essential to system administration.
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must be configured so that the rsyslog daemon does not accept log messages from other servers unless the server is being used for log aggregation.
Medium Severity
Unintentionally running a rsyslog server accepting remote messages puts the system at increased risk. Malicious rsyslog messages sent to the server could exploit vulnerabilities in the server software itself, could introduce misleading information into the system's logs, or could fill the system's storage leading to a denial of service. If the system is intended to be a log aggregation server, its use must be documented with the information system security officer (ISSO).
SRG-OS-000032-GPOS-00013
1 Rule
All RHEL 9 remote access methods must be monitored.
Medium Severity
Logging remote access methods can be used to trace the decrease in the risks associated with remote user access management. It can also be used to spot cyberattacks and ensure ongoing compliance with organizational policies surrounding the use of remote access methods.
SRG-OS-000342-GPOS-00133
1 Rule
RHEL 9 must authenticate the remote logging server for offloading audit logs via rsyslog.
Medium Severity
Information stored in one location is vulnerable to accidental or incidental deletion or alteration. Offloading is a common process in information systems with limited audit storage capacity. RHEL 9 installation media provides "rsyslogd", a system utility providing support for message logging. Support for both internet and Unix domain sockets enables this utility to support both local and remote logging. Coupling this utility with "gnutls" (a secure communications library implementing the SSL, TLS and DTLS protocols) creates a method to securely encrypt and offload auditing. "Rsyslog" supported authentication modes include: anon - anonymous authentication x509/fingerprint - certificate fingerprint authentication x509/certvalid - certificate validation only x509/name - certificate validation and subject name authentication Satisfies: SRG-OS-000342-GPOS-00133, SRG-OS-000479-GPOS-00224
SRG-OS-000342-GPOS-00133
1 Rule
RHEL 9 must encrypt the transfer of audit records offloaded onto a different system or media from the system being audited via rsyslog.
Medium Severity
Information stored in one location is vulnerable to accidental or incidental deletion or alteration. Offloading is a common process in information systems with limited audit storage capacity. RHEL 9 installation media provides "rsyslogd", a system utility providing support for message logging. Support for both internet and Unix domain sockets enables this utility to support both local and remote logging. Coupling this utility with "gnutls" (a secure communications library implementing the SSL, TLS and DTLS protocols) creates a method to securely encrypt and offload auditing. "Rsyslog" supported authentication modes include: anon - anonymous authentication x509/fingerprint - certificate fingerprint authentication x509/certvalid - certificate validation only x509/name - certificate validation and subject name authentication Satisfies: SRG-OS-000342-GPOS-00133, SRG-OS-000479-GPOS-00224
SRG-OS-000342-GPOS-00133
1 Rule
RHEL 9 must encrypt via the gtls driver the transfer of audit records offloaded onto a different system or media from the system being audited via rsyslog.
Medium Severity
Information stored in one location is vulnerable to accidental or incidental deletion or alteration. Offloading is a common process in information systems with limited audit storage capacity. RHEL 9 installation media provides "rsyslogd", a system utility providing support for message logging. Support for both internet and Unix domain sockets enables this utility to support both local and remote logging. Coupling this utility with "gnutls" (a secure communications library implementing the SSL, TLS and DTLS protocols) creates a method to securely encrypt and offload auditing. Satisfies: SRG-OS-000342-GPOS-00133, SRG-OS-000479-GPOS-00224
SRG-OS-000479-GPOS-00224
1 Rule
RHEL 9 must be configured to forward audit records via TCP to a different system or media from the system being audited via rsyslog.
Medium Severity
Information stored in one location is vulnerable to accidental or incidental deletion or alteration. Offloading is a common process in information systems with limited audit storage capacity. RHEL 9 installation media provides "rsyslogd", a system utility providing support for message logging. Support for both internet and Unix domain sockets enables this utility to support both local and remote logging. Coupling this utility with "gnutls" (a secure communications library implementing the SSL, TLS and DTLS protocols) creates a method to securely encrypt and offload auditing. Rsyslog provides three ways to forward message: the traditional UDP transport, which is extremely lossy but standard; the plain TCP based transport, which loses messages only during certain situations but is widely available; and the RELP transport, which does not lose messages but is currently available only as part of the rsyslogd 3.15.0 and above. Examples of each configuration: UDP *.* @remotesystemname TCP *.* @@remotesystemname RELP *.* :omrelp:remotesystemname:2514 Note that a port number was given as there is no standard port for RELP. Satisfies: SRG-OS-000479-GPOS-00224, SRG-OS-000480-GPOS-00227, SRG-OS-000342-GPOS-00133
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must use cron logging.
Medium Severity
Cron logging can be used to trace the successful or unsuccessful execution of cron jobs. It can also be used to spot intrusions into the use of the cron facility by unauthorized and malicious users.
SRG-OS-000062-GPOS-00031
1 Rule
RHEL 9 audit package must be installed.
Medium Severity
Without establishing what type of events occurred, the source of events, where events occurred, and the outcome of events, it would be difficult to establish, correlate, and investigate the events leading up to an outage or attack. Audit record content that may be necessary to satisfy this requirement includes, for example, time stamps, source and destination addresses, user/process identifiers, event descriptions, success/fail indications, filenames involved, and access control or flow control rules invoked. Associating event types with detected events in audit logs provides a means of investigating an attack, recognizing resource utilization or capacity thresholds, or identifying an improperly configured RHEL 9 system. Satisfies: SRG-OS-000062-GPOS-00031, SRG-OS-000037-GPOS-00015, SRG-OS-000038-GPOS-00016, SRG-OS-000039-GPOS-00017, SRG-OS-000040-GPOS-00018, SRG-OS-000041-GPOS-00019, SRG-OS-000042-GPOS-00021, SRG-OS-000051-GPOS-00024, SRG-OS-000054-GPOS-00025, SRG-OS-000122-GPOS-00063, SRG-OS-000254-GPOS-00095, SRG-OS-000255-GPOS-00096, SRG-OS-000337-GPOS-00129, SRG-OS-000348-GPOS-00136, SRG-OS-000349-GPOS-00137, SRG-OS-000350-GPOS-00138, SRG-OS-000351-GPOS-00139, SRG-OS-000352-GPOS-00140, SRG-OS-000353-GPOS-00141, SRG-OS-000354-GPOS-00142, SRG-OS-000358-GPOS-00145, SRG-OS-000365-GPOS-00152, SRG-OS-000392-GPOS-00172, SRG-OS-000475-GPOS-00220, SRG-OS-000055-GPOS-00026
SRG-OS-000062-GPOS-00031
1 Rule
RHEL 9 audit service must be enabled.
Medium Severity
Without establishing what type of events occurred, it would be difficult to establish, correlate, and investigate the events leading up to an outage or attack. Ensuring the "auditd" service is active ensures audit records generated by the kernel are appropriately recorded. Additionally, a properly configured audit subsystem ensures that actions of individual system users can be uniquely traced to those users so they can be held accountable for their actions. Satisfies: SRG-OS-000062-GPOS-00031, SRG-OS-000037-GPOS-00015, SRG-OS-000038-GPOS-00016, SRG-OS-000039-GPOS-00017, SRG-OS-000040-GPOS-00018, SRG-OS-000041-GPOS-00019, SRG-OS-000042-GPOS-00021, SRG-OS-000051-GPOS-00024, SRG-OS-000054-GPOS-00025, SRG-OS-000122-GPOS-00063, SRG-OS-000254-GPOS-00095, SRG-OS-000255-GPOS-00096, SRG-OS-000337-GPOS-00129, SRG-OS-000348-GPOS-00136, SRG-OS-000349-GPOS-00137, SRG-OS-000350-GPOS-00138, SRG-OS-000351-GPOS-00139, SRG-OS-000352-GPOS-00140, SRG-OS-000353-GPOS-00141, SRG-OS-000354-GPOS-00142, SRG-OS-000358-GPOS-00145, SRG-OS-000365-GPOS-00152, SRG-OS-000392-GPOS-00172, SRG-OS-000475-GPOS-00220
SRG-OS-000047-GPOS-00023
1 Rule
RHEL 9 audit system must take appropriate action when an error writing to the audit storage volume occurs.
Medium Severity
It is critical that when the operating system is at risk of failing to process audit logs as required, it takes action to mitigate the failure. Audit processing failures include software/hardware errors; failures in the audit capturing mechanisms; and audit storage capacity being reached or exceeded. Responses to audit failure depend upon the nature of the failure mode.
SRG-OS-000047-GPOS-00023
1 Rule
RHEL 9 audit system must take appropriate action when the audit storage volume is full.
Medium Severity
It is critical that when the operating system is at risk of failing to process audit logs as required, it takes action to mitigate the failure. Audit processing failures include software/hardware errors; failures in the audit capturing mechanisms; and audit storage capacity being reached or exceeded. Responses to audit failure depend upon the nature of the failure mode.
SRG-OS-000341-GPOS-00132
1 Rule
RHEL 9 must allocate audit record storage capacity to store at least one week's worth of audit records.
Medium Severity
To ensure RHEL 9 systems have a sufficient storage capacity in which to write the audit logs, RHEL 9 needs to be able to allocate audit record storage capacity. The task of allocating audit record storage capacity is usually performed during initial installation of RHEL 9. Satisfies: SRG-OS-000341-GPOS-00132, SRG-OS-000342-GPOS-00133
SRG-OS-000343-GPOS-00134
1 Rule
RHEL 9 must take action when allocated audit record storage volume reaches 75 percent of the repository maximum audit record storage capacity.
Medium Severity
If security personnel are not notified immediately when storage volume reaches 75 percent utilization, they are unable to plan for audit record storage capacity expansion.
SRG-OS-000343-GPOS-00134
1 Rule
RHEL 9 must notify the system administrator (SA) and information system security officer (ISSO) (at a minimum) when allocated audit record storage volume 75 percent utilization.
Medium Severity
If security personnel are not notified immediately when storage volume reaches 75 percent utilization, they are unable to plan for audit record storage capacity expansion.
SRG-OS-000343-GPOS-00134
1 Rule
RHEL 9 must take action when allocated audit record storage volume reaches 95 percent of the audit record storage capacity.
Medium Severity
If action is not taken when storage volume reaches 95 percent utilization, the auditing system may fail when the storage volume reaches capacity.
SRG-OS-000343-GPOS-00134
1 Rule
RHEL 9 must take action when allocated audit record storage volume reaches 95 percent of the repository maximum audit record storage capacity.
Medium Severity
If action is not taken when storage volume reaches 95 percent utilization, the auditing system may fail when the storage volume reaches capacity.
SRG-OS-000047-GPOS-00023
1 Rule
RHEL 9 audit system must take appropriate action when the audit files have reached maximum size.
Medium Severity
It is critical that when the operating system is at risk of failing to process audit logs as required, it takes action to mitigate the failure. Audit processing failures include software/hardware errors; failures in the audit capturing mechanisms; and audit storage capacity being reached or exceeded. Responses to audit failure depend upon the nature of the failure mode.
SRG-OS-000039-GPOS-00017
1 Rule
RHEL 9 must label all offloaded audit logs before sending them to the central log server.
Medium Severity
Enriched logging is needed to determine who, what, and when events occur on a system. Without this, determining root cause of an event will be much more difficult. When audit logs are not labeled before they are sent to a central log server, the audit data will not be able to be analyzed and tied back to the correct system. Satisfies: SRG-OS-000039-GPOS-00017, SRG-OS-000342-GPOS-00133, SRG-OS-000479-GPOS-00224
SRG-OS-000342-GPOS-00133
1 Rule
RHEL 9 must take appropriate action when the internal event queue is full.
Medium Severity
The audit system should have an action setup in the event the internal event queue becomes full so that no data is lost. Information stored in one location is vulnerable to accidental or incidental deletion or alteration. Offloading is a common process in information systems with limited audit storage capacity. Satisfies: SRG-OS-000342-GPOS-00133, SRG-OS-000479-GPOS-00224
SRG-OS-000046-GPOS-00022
1 Rule
RHEL 9 System Administrator (SA) and/or information system security officer (ISSO) (at a minimum) must be alerted of an audit processing failure event.
Medium Severity
It is critical for the appropriate personnel to be aware if a system is at risk of failing to process audit logs as required. Without this notification, the security personnel may be unaware of an impending failure of the audit capability, and system operation may be adversely affected. Audit processing failures include software/hardware errors, failures in the audit capturing mechanisms, and audit storage capacity being reached or exceeded. This requirement applies to each audit data storage repository (i.e., distinct information system component where audit records are stored), the centralized audit storage capacity of organizations (i.e., all audit data storage repositories combined), or both. Satisfies: SRG-OS-000046-GPOS-00022, SRG-OS-000343-GPOS-00134
SRG-OS-000062-GPOS-00031
1 Rule
RHEL 9 audit system must audit local events.
Medium Severity
Without establishing what type of events occurred, the source of events, where events occurred, and the outcome of events, it would be difficult to establish, correlate, and investigate the events leading up to an outage or attack. If option "local_events" isn't set to "yes" only events from network will be aggregated. Satisfies: SRG-OS-000062-GPOS-00031, SRG-OS-000480-GPOS-00227
SRG-OS-000057-GPOS-00027
1 Rule
RHEL 9 audit logs must be group-owned by root or by a restricted logging group to prevent unauthorized read access.
Medium Severity
Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality. Satisfies: SRG-OS-000057-GPOS-00027, SRG-OS-000058-GPOS-00028, SRG-OS-000059-GPOS-00029, SRG-OS-000206-GPOS-00084
SRG-OS-000057-GPOS-00027
1 Rule
RHEL 9 audit log directory must be owned by root to prevent unauthorized read access.
Medium Severity
Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality. Satisfies: SRG-OS-000057-GPOS-00027, SRG-OS-000058-GPOS-00028, SRG-OS-000059-GPOS-00029, SRG-OS-000206-GPOS-00084
SRG-OS-000057-GPOS-00027
1 Rule
RHEL 9 audit logs file must have mode 0600 or less permissive to prevent unauthorized access to the audit log.
Medium Severity
Only authorized personnel should be aware of errors and the details of the errors. Error messages are an indicator of an organization's operational state or can identify the RHEL 9 system or platform. Additionally, Personally Identifiable Information (PII) and operational information must not be revealed through error messages to unauthorized personnel or their designated representatives. The structure and content of error messages must be carefully considered by the organization and development team. The extent to which the information system is able to identify and handle error conditions is guided by organizational policy and operational requirements. Satisfies: SRG-OS-000057-GPOS-00027, SRG-OS-000058-GPOS-00028, SRG-OS-000059-GPOS-00029, SRG-OS-000206-GPOS-00084
SRG-OS-000051-GPOS-00024
1 Rule
RHEL 9 must periodically flush audit records to disk to prevent the loss of audit records.
Medium Severity
If option "freq" is not set to a value that requires audit records being written to disk after a threshold number is reached, then audit records may be lost.
SRG-OS-000255-GPOS-00096
1 Rule
RHEL 9 must produce audit records containing information to establish the identity of any individual or process associated with the event.
Medium Severity
Without establishing what type of events occurred, the source of events, where events occurred, and the outcome of events, it would be difficult to establish, correlate, and investigate the events leading up to an outage or attack. Audit record content that may be necessary to satisfy this requirement includes, for example, time stamps, source and destination addresses, user/process identifiers, event descriptions, success/fail indications, filenames involved, and access control or flow control rules invoked. Enriched logging aids in making sense of who, what, and when events occur on a system. Without this, determining root cause of an event will be much more difficult. Satisfies: SRG-OS-000255-GPOS-00096, SRG-OS-000480-GPOS-00227
SRG-OS-000480-GPOS-00227
1 Rule
RHEL 9 must write audit records to disk.
Medium Severity
Audit data should be synchronously written to disk to ensure log integrity. This setting assures that all audit event data is written disk.
SRG-OS-000063-GPOS-00032
1 Rule
RHEL 9 must allow only the information system security manager (ISSM) (or individuals or roles appointed by the ISSM) to select which auditable events are to be audited.
Medium Severity
Without the capability to restrict the roles and individuals that can select which events are audited, unauthorized personnel may be able to prevent the auditing of critical events. Misconfigured audits may degrade the system's performance by overwhelming the audit log. Misconfigured audits may also make it more difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.
SRG-OS-000063-GPOS-00032
1 Rule
RHEL 9 /etc/audit/auditd.conf file must have 0640 or less permissive to prevent unauthorized access.
Medium Severity
Without the capability to restrict the roles and individuals that can select which events are audited, unauthorized personnel may be able to prevent the auditing of critical events. Misconfigured audits may degrade the system's performance by overwhelming the audit log. Misconfigured audits may also make it more difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.
SRG-OS-000254-GPOS-00095
1 Rule
RHEL 9 must allocate an audit_backlog_limit of sufficient size to capture processes that start prior to the audit daemon.
Low Severity
Without the capability to generate audit records, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. If auditing is enabled late in the startup process, the actions of some startup processes may not be audited. Some audit systems also maintain state information only available if auditing is enabled before a given process is created. Audit records can be generated from various components within the information system (e.g., module or policy filter). Allocating an audit_backlog_limit of sufficient size is critical in maintaining a stable boot process. With an insufficient limit allocated, the system is susceptible to boot failures and crashes. Satisfies: SRG-OS-000254-GPOS-00095, SRG-OS-000341-GPOS-00132
SRG-OS-000046-GPOS-00022
1 Rule
RHEL 9 must have mail aliases to notify the information system security officer (ISSO) and system administrator (SA) (at a minimum) in the event of an audit processing failure.
Medium Severity
It is critical for the appropriate personnel to be aware if a system is at risk of failing to process audit logs as required. Without this notification, the security personnel may be unaware of an impending failure of the audit capability, and system operation may be adversely affected. Audit processing failures include software/hardware errors, failures in the audit capturing mechanisms, and audit storage capacity being reached or exceeded. This requirement applies to each audit data storage repository (i.e., distinct information system component where audit records are stored), the centralized audit storage capacity of organizations (i.e., all audit data storage repositories combined), or both.
SRG-OS-000342-GPOS-00133
1 Rule
RHEL 9 audispd-plugins package must be installed.
Medium Severity
"audispd-plugins" provides plugins for the real-time interface to the audit subsystem, "audispd". These plugins can do things like relay events to remote machines or analyze events for suspicious behavior.
SRG-OS-000326-GPOS-00126
1 Rule
RHEL 9 must audit uses of the "execve" system call.
Medium Severity
Misuse of privileged functions, either intentionally or unintentionally by authorized users, or by unauthorized external entities that have compromised information system accounts, is a serious and ongoing concern and can have significant adverse impacts on organizations. Auditing the use of privileged functions is one way to detect such misuse and identify the risk from insider threats and the advanced persistent threat. Satisfies: SRG-OS-000326-GPOS-00126, SRG-OS-000327-GPOS-00127
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the chmod, fchmod, and fchmodat system calls.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000064-GPOS-00033, SRG-OS-000466-GPOS-00210, SRG-OS-000458-GPOS-00203
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the chown, fchown, fchownat, and lchown system calls.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000064-GPOS-00033, SRG-OS-000466-GPOS-00210, SRG-OS-000458-GPOS-00203, SRG-OS-000474-GPOS-00219
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the setxattr, fsetxattr, lsetxattr, removexattr, fremovexattr, and lremovexattr system calls.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000458-GPOS-00203, SRG-OS-000462-GPOS-00206, SRG-OS-000463-GPOS-00207, SRG-OS-000471-GPOS-00215, SRG-OS-000474-GPOS-00219, SRG-OS-000466-GPOS-00210, SRG-OS-000064-GPOS-00033
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of umount system calls.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the chacl command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000466-GPOS-00210
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the setfacl command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the chcon command.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account that is being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000468-GPOS-00212, SRG-OS-000471-GPOS-00215, SRG-OS-000463-GPOS-00207, SRG-OS-000465-GPOS-00209
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the semanage command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000463-GPOS-00207, SRG-OS-000465-GPOS-00209
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the setfiles command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000463-GPOS-00207, SRG-OS-000465-GPOS-00209
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the setsebool command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000463-GPOS-00207, SRG-OS-000465-GPOS-00209
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the rename, unlink, rmdir, renameat, and unlinkat system calls.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000466-GPOS-00210, SRG-OS-000467-GPOS-00211, SRG-OS-000468-GPOS-00212
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the truncate, ftruncate, creat, open, openat, and open_by_handle_at system calls.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000064-GPOS-00033, SRG-OS-000458-GPOS-00203, SRG-OS-000461-GPOS-00205
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the delete_module system call.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000471-GPOS-00216, SRG-OS-000477-GPOS-00222
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the init_module and finit_module system calls.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000471-GPOS-00216, SRG-OS-000477-GPOS-00222
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the chage command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000468-GPOS-00212, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the chsh command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the crontab command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the gpasswd command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the kmod command.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000471-GPOS-00216, SRG-OS-000477-GPOS-00222
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the newgrp command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account that is being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the pam_timestamp_check command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the passwd command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the postdrop command.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the postqueue command.
Medium Severity
Without generating audit record specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the ssh-agent command.
Medium Severity
Without generating audit record specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the ssh-keysign command.
Medium Severity
Without generating audit record specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the su command.
Medium Severity
Without generating audit record specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000064-GPOS-00033, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000466-GPOS-00210
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the sudo command.
Medium Severity
Without generating audit record specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000466-GPOS-00210
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the sudoedit command.
Medium Severity
Without generating audit record specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the unix_chkpwd command.
Medium Severity
Without generating audit record specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the unix_update command.
Medium Severity
Without generating audit record specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000064-GPOS-00033, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the userhelper command.
Medium Severity
Without generating audit record specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the usermod command.
Medium Severity
Without generating audit record specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000466-GPOS-00210
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must audit all uses of the mount command.
Medium Severity
Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account that is being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. The system call rules are loaded into a matching engine that intercepts each system call made by all programs on the system. Therefore, it is very important to use system call rules only when absolutely necessary since these affect performance. The more rules, the bigger the performance hit. The performance can be helped, however, by combining system calls into one rule whenever possible. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000477-GPOS-00222
1 Rule
Successful/unsuccessful uses of the init command in RHEL 9 must generate an audit record.
Medium Severity
Misuse of the init command may cause availability issues for the system.
SRG-OS-000477-GPOS-00222
1 Rule
Successful/unsuccessful uses of the poweroff command in RHEL 9 must generate an audit record.
Medium Severity
Misuse of the poweroff command may cause availability issues for the system.
SRG-OS-000477-GPOS-00222
1 Rule
Successful/unsuccessful uses of the reboot command in RHEL 9 must generate an audit record.
Medium Severity
Misuse of the reboot command may cause availability issues for the system.
SRG-OS-000477-GPOS-00222
1 Rule
Successful/unsuccessful uses of the shutdown command in RHEL 9 must generate an audit record.
Medium Severity
Misuse of the shutdown command may cause availability issues for the system.
SRG-OS-000037-GPOS-00015
1 Rule
Successful/unsuccessful uses of the umount system call in RHEL 9 must generate an audit record.
Medium Severity
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000037-GPOS-00015
1 Rule
Successful/unsuccessful uses of the umount2 system call in RHEL 9 must generate an audit record.
Medium Severity
The changing of file permissions could indicate that a user is attempting to gain access to information that would otherwise be disallowed. Auditing DAC modifications can facilitate the identification of patterns of abuse among both authorized and unauthorized users. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215
SRG-OS-000004-GPOS-00004
1 Rule
RHEL 9 must generate audit records for all account creations, modifications, disabling, and termination events that affect /etc/sudoers.
Medium Severity
The actions taken by system administrators must be audited to keep a record of what was executed on the system, as well as for accountability purposes. Editing the sudoers file may be sign of an attacker trying to establish persistent methods to a system, auditing the editing of the sudoers files mitigates this risk. Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000304-GPOS-00121, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000470-GPOS-00214, SRG-OS-000471-GPOS-00215, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000466-GPOS-00210, SRG-OS-000476-GPOS-00221
SRG-OS-000004-GPOS-00004
1 Rule
RHEL 9 must generate audit records for all account creations, modifications, disabling, and termination events that affect /etc/sudoers.d/ directory.
Medium Severity
The actions taken by system administrators must be audited to keep a record of what was executed on the system, as well as for accountability purposes. Editing the sudoers file may be sign of an attacker trying to establish persistent methods to a system, auditing the editing of the sudoers files mitigates this risk. Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000304-GPOS-00121, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000470-GPOS-00214, SRG-OS-000471-GPOS-00215, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000466-GPOS-00210, SRG-OS-000476-GPOS-00221
SRG-OS-000004-GPOS-00004
1 Rule
RHEL 9 must generate audit records for all account creations, modifications, disabling, and termination events that affect /etc/group.
Medium Severity
In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications must be investigated for legitimacy. Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000304-GPOS-00121, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000470-GPOS-00214, SRG-OS-000471-GPOS-00215, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000466-GPOS-00210, SRG-OS-000476-GPOS-00221
SRG-OS-000004-GPOS-00004
1 Rule
RHEL 9 must generate audit records for all account creations, modifications, disabling, and termination events that affect /etc/gshadow.
Medium Severity
In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy. Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000304-GPOS-00121, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000470-GPOS-00214, SRG-OS-000471-GPOS-00215, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000466-GPOS-00210, SRG-OS-000476-GPOS-00221
SRG-OS-000004-GPOS-00004
1 Rule
RHEL 9 must generate audit records for all account creations, modifications, disabling, and termination events that affect /etc/opasswd.
Medium Severity
In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy. Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000304-GPOS-00121, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000470-GPOS-00214, SRG-OS-000471-GPOS-00215, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000466-GPOS-00210, SRG-OS-000476-GPOS-00221
SRG-OS-000004-GPOS-00004
1 Rule
RHEL 9 must generate audit records for all account creations, modifications, disabling, and termination events that affect /etc/passwd.
Medium Severity
In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy. Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000304-GPOS-00121, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000470-GPOS-00214, SRG-OS-000471-GPOS-00215, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000466-GPOS-00210, SRG-OS-000476-GPOS-00221, SRG-OS-000274-GPOS-00104, SRG-OS-000275-GPOS-00105, SRG-OS-000276-GPOS-00106, SRG-OS-000277-GPOS-00107
SRG-OS-000004-GPOS-00004
1 Rule
RHEL 9 must generate audit records for all account creations, modifications, disabling, and termination events that affect /etc/shadow.
Medium Severity
In addition to auditing new user and group accounts, these watches will alert the system administrator(s) to any modifications. Any unexpected users, groups, or modifications should be investigated for legitimacy. Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000304-GPOS-00121, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000470-GPOS-00214, SRG-OS-000471-GPOS-00215, SRG-OS-000239-GPOS-00089, SRG-OS-000240-GPOS-00090, SRG-OS-000241-GPOS-00091, SRG-OS-000303-GPOS-00120, SRG-OS-000466-GPOS-00210, SRG-OS-000476-GPOS-00221
SRG-OS-000392-GPOS-00172
1 Rule
RHEL 9 must generate audit records for all account creations, modifications, disabling, and termination events that affect /var/log/faillock.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Satisfies: SRG-OS-000392-GPOS-00172, SRG-OS-000470-GPOS-00214, SRG-OS-000473-GPOS-00218
SRG-OS-000037-GPOS-00015
1 Rule
RHEL 9 must generate audit records for all account creations, modifications, disabling, and termination events that affect /var/log/lastlog.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Satisfies: SRG-OS-000037-GPOS-00015, SRG-OS-000042-GPOS-00020, SRG-OS-000062-GPOS-00031, SRG-OS-000392-GPOS-00172, SRG-OS-000462-GPOS-00206, SRG-OS-000471-GPOS-00215, SRG-OS-000473-GPOS-00218, SRG-OS-000470-GPOS-00214
SRG-OS-000392-GPOS-00172
1 Rule
RHEL 9 must generate audit records for all account creations, modifications, disabling, and termination events that affect /var/log/tallylog.
Medium Severity
Without generating audit records specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Satisfies: SRG-OS-000392-GPOS-00172, SRG-OS-000470-GPOS-00214, SRG-OS-000473-GPOS-00218
SRG-OS-000046-GPOS-00022
1 Rule
RHEL 9 must take appropriate action when a critical audit processing failure occurs.
Medium Severity
It is critical for the appropriate personnel to be aware if a system is at risk of failing to process audit logs as required. Without this notification, the security personnel may be unaware of an impending failure of the audit capability, and system operation may be adversely affected. Audit processing failures include software/hardware errors, failures in the audit capturing mechanisms, and audit storage capacity being reached or exceeded. Satisfies: SRG-OS-000046-GPOS-00022, SRG-OS-000047-GPOS-00023
SRG-OS-000462-GPOS-00206
1 Rule
RHEL 9 audit system must protect logon UIDs from unauthorized change.
Medium Severity
If modification of login user identifiers (UIDs) is not prevented, they can be changed by nonprivileged users and make auditing complicated or impossible. Satisfies: SRG-OS-000462-GPOS-00206, SRG-OS-000475-GPOS-00220, SRG-OS-000057-GPOS-00027, SRG-OS-000058-GPOS-00028, SRG-OS-000059-GPOS-00029
SRG-OS-000057-GPOS-00027
1 Rule
RHEL 9 audit system must protect auditing rules from unauthorized change.
Medium Severity
Unauthorized disclosure of audit records can reveal system and configuration data to attackers, thus compromising its confidentiality. Audit information includes all information (e.g., audit records, audit settings, audit reports) needed to successfully audit RHEL 9 system activity. In immutable mode, unauthorized users cannot execute changes to the audit system to potentially hide malicious activity and then put the audit rules back. A system reboot would be noticeable, and a system administrator could then investigate the unauthorized changes. Satisfies: SRG-OS-000057-GPOS-00027, SRG-OS-000058-GPOS-00028, SRG-OS-000059-GPOS-00029
SRG-OS-000033-GPOS-00014
1 Rule
RHEL 9 must enable FIPS mode.
High Severity
Use of weak or untested encryption algorithms undermines the purposes of utilizing encryption to protect data. The operating system must implement cryptographic modules adhering to the higher standards approved by the federal government since this provides assurance they have been tested and validated. This includes NIST FIPS-validated cryptography for the following: Provisioning digital signatures, generating cryptographic hashes, and to protect data requiring data-at-rest protections in accordance with applicable federal laws, Executive Orders, directives, policies, regulations, and standards. Satisfies: SRG-OS-000033-GPOS-00014, SRG-OS-000125-GPOS-00065, SRG-OS-000396-GPOS-00176, SRG-OS-000423-GPOS-00187, SRG-OS-000478-GPOS-00223
SRG-OS-000073-GPOS-00041
1 Rule
RHEL 9 must employ FIPS 140-3 approved cryptographic hashing algorithms for all stored passwords.
Medium Severity
The system must use a strong hashing algorithm to store the password. Passwords need to be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised. Satisfies: SRG-OS-000073-GPOS-00041, SRG-OS-000120-GPOS-00061
SRG-OS-000033-GPOS-00014
1 Rule
RHEL 9 IP tunnels must use FIPS 140-3 approved cryptographic algorithms.
Medium Severity
Overriding the system crypto policy makes the behavior of the Libreswan service violate expectations, and makes system configuration more fragmented.
SRG-OS-000073-GPOS-00041
1 Rule
RHEL 9 pam_unix.so module must be configured in the password-auth file to use a FIPS 140-3 approved cryptographic hashing algorithm for system authentication.
Medium Severity
Unapproved mechanisms that are used for authentication to the cryptographic module are not verified and; therefore, cannot be relied upon to provide confidentiality or integrity, and DOD data may be compromised. RHEL 9 systems utilizing encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules. FIPS 140-3 is the current standard for validating that mechanisms used to access cryptographic modules utilize authentication that meets DOD requirements. This allows for Security Levels 1, 2, 3, or 4 for use on a general-purpose computing system.
SRG-OS-000396-GPOS-00176
1 Rule
RHEL 9 must have the crypto-policies package installed.
Medium Severity
Centralized cryptographic policies simplify applying secure ciphers across an operating system and the applications that run on that operating system. Use of weak or untested encryption algorithms undermines the purposes of using encryption to protect data. Satisfies: SRG-OS-000396-GPOS-00176, SRG-OS-000393-GPOS-00173, SRG-OS-000394-GPOS-00174
SRG-OS-000396-GPOS-00176
1 Rule
RHEL 9 cryptographic policy must not be overridden.
High Severity
Centralized cryptographic policies simplify applying secure ciphers across an operating system and the applications that run on that operating system. Use of weak or untested encryption algorithms undermines the purposes of using encryption to protect data. Satisfies: SRG-OS-000396-GPOS-00176, SRG-OS-000393-GPOS-00173, SRG-OS-000394-GPOS-00174
SRG-OS-000120-GPOS-00061
1 Rule
RHEL 9 must use mechanisms meeting the requirements of applicable federal laws, executive orders, directives, policies, regulations, standards, and guidance for authentication to a cryptographic module.
Medium Severity
Overriding the system crypto policy makes the behavior of Kerberos violate expectations and makes system configuration more fragmented.
SRG-OS-000396-GPOS-00176
1 Rule
RHEL 9 must implement a FIPS 140-3 compliant systemwide cryptographic policy.
Medium Severity
Centralized cryptographic policies simplify applying secure ciphers across an operating system and the applications that run on that operating system. Use of weak or untested encryption algorithms undermines the purposes of using encryption to protect data. Satisfies: SRG-OS-000396-GPOS-00176, SRG-OS-000393-GPOS-00173, SRG-OS-000394-GPOS-00174
SRG-OS-000423-GPOS-00187
1 Rule
RHEL 9 must implement DOD-approved encryption in the bind package.
Medium Severity
Without cryptographic integrity protections, information can be altered by unauthorized users without detection. Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash. RHEL 9 incorporates system-wide crypto policies by default. The employed algorithms can be viewed in the /etc/crypto-policies/back-ends/ directory. Satisfies: SRG-OS-000423-GPOS-00187, SRG-OS-000426-GPOS-00190
SRG-OS-000023-GPOS-00006
1 Rule
RHEL 9 must display the Standard Mandatory DOD Notice and Consent Banner before granting local or remote access to the system via a graphical user logon.
Medium Severity
Display of a standardized and approved use notification before granting access to the operating system ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executive Orders, directives, policies, regulations, standards, and guidance. System use notifications are required only for access via logon interfaces with human users and are not required when such human interfaces do not exist. The banner must be formatted in accordance with applicable DOD policy. Use the following verbiage for operating systems that can accommodate banners of 1300 characters: "You are accessing a U.S. Government (USG) Information System (IS) that is provided for USG-authorized use only. By using this IS (which includes any device attached to this IS), you consent to the following conditions: -The USG routinely intercepts and monitors communications on this IS for purposes including, but not limited to, penetration testing, COMSEC monitoring, network operations and defense, personnel misconduct (PM), law enforcement (LE), and counterintelligence (CI) investigations. -At any time, the USG may inspect and seize data stored on this IS. -Communications using, or data stored on, this IS are not private, are subject to routine monitoring, interception, and search, and may be disclosed or used for any USG-authorized purpose. -This IS includes security measures (e.g., authentication and access controls) to protect USG interests--not for your personal benefit or privacy. -Notwithstanding the above, using this IS does not constitute consent to PM, LE or CI investigative searching or monitoring of the content of privileged communications, or work product, related to personal representation or services by attorneys, psychotherapists, or clergy, and their assistants. Such communications and work product are private and confidential. See User Agreement for details." Satisfies: SRG-OS-000023-GPOS-00006, SRG-OS-000228-GPOS-00088
SRG-OS-000080-GPOS-00048
1 Rule
RHEL 9 "/etc/audit/" must be owned by root.
Medium Severity
The "/etc/audit/" directory contains files that ensure the proper auditing of command execution, privilege escalation, file manipulation, and more. Protection of this directory is critical for system security.
SRG-OS-000080-GPOS-00048
1 Rule
RHEL 9 "/etc/audit/" must be group-owned by root.
Medium Severity
The "/etc/audit/" directory contains files that ensure the proper auditing of command execution, privilege escalation, file manipulation, and more. Protection of this directory is critical for system security.
SRG-OS-000250-GPOS-00093
1 Rule
The RHEL 9 SSH client must be configured to use only DOD-approved encryption ciphers employing FIPS 140-3 validated cryptographic hash algorithms to protect the confidentiality of SSH client connections.
Medium Severity
Without cryptographic integrity protections, information can be altered by unauthorized users without detection. Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography, enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash. RHEL 9 incorporates systemwide crypto policies by default. The SSH configuration file has no effect on the ciphers, MACs, or algorithms unless specifically defined in the /etc/sysconfig/sshd file. The employed algorithms can be viewed in the /etc/crypto-policies/back-ends/openssh.config file.
SRG-OS-000250-GPOS-00093
1 Rule
The RHEL 9 SSH client must be configured to use only DOD-approved Message Authentication Codes (MACs) employing FIPS 140-3 validated cryptographic hash algorithms to protect the confidentiality of SSH client connections.
Medium Severity
Without cryptographic integrity protections, information can be altered by unauthorized users without detection. Remote access (e.g., RDP) is access to DOD nonpublic information systems by an authorized user (or an information system) communicating through an external, nonorganization-controlled network. Remote access methods include, for example, dial-up, broadband, and wireless. Cryptographic mechanisms used for protecting the integrity of information include, for example, signed hash functions using asymmetric cryptography, enabling distribution of the public key to verify the hash information while maintaining the confidentiality of the secret key used to generate the hash. RHEL 9 incorporates systemwide crypto policies by default. The SSH configuration file has no effect on the ciphers, MACs, or algorithms unless specifically defined in the /etc/sysconfig/sshd file. The employed algorithms can be viewed in the /etc/crypto-policies/back-ends/openssh.config file.
SRG-OS-000368-GPOS-00154
1 Rule
The RHEL 9 fapolicy module must be configured to employ a deny-all, permit-by-exception policy to allow the execution of authorized software programs.
Medium Severity
The organization must identify authorized software programs and permit execution of authorized software. The process used to identify software programs that are authorized to execute on organizational information systems is commonly referred to as allow listing. Using an allow list provides a configuration management method for allowing the execution of only authorized software. Using only authorized software decreases risk by limiting the number of potential vulnerabilities. Verification of allow listed software occurs prior to execution or at system startup. User home directories/folders may contain information of a sensitive nature. Nonprivileged users should coordinate any sharing of information with an SA through shared resources. RHEL 9 ships with many optional packages. One such package is a file access policy daemon called "fapolicyd". "fapolicyd" is a userspace daemon that determines access rights to files based on attributes of the process and file. It can be used to either block list or allow list processes or file access. Proceed with caution with enforcing the use of this daemon. Improper configuration may render the system nonfunctional. The "fapolicyd" API is not namespace aware and can cause issues when launching or running containers. Satisfies: SRG-OS-000368-GPOS-00154, SRG-OS-000370-GPOS-00155, SRG-OS-000480-GPOS-00232