SUSE Linux Enterprise Micro (SLEM) 5 Security Technical Implementation Guide
Rules, Groups, and Values defined within the XCCDF Benchmark
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SRG-OS-000480-GPOS-00227
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SLEM 5 must be a vendor-supported release.
A SLEM 5 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 discove...Rule High Severity -
SLEM 5 must display the Standard Mandatory DOD Notice and Consent Banner before granting any local or remote connection to the system.
Display of a standardized and approved use notification before granting access to SLEM 5 ensures privacy and security notification verbiage used is consistent with applicable federal laws, Executiv...Rule Medium Severity -
SLEM 5 must restrict access to the kernel message buffer.
Restricting access to the kernel message buffer limits access only to root. This prevents attackers from gaining additional system information as a nonprivileged user.Rule Medium Severity -
Address space layout randomization (ASLR) must be implemented by SLEM 5 to protect memory from unauthorized code execution.
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 inclu...Rule Medium Severity -
Vendor-packaged SLEM 5 security patches and updates must be installed and up to date.
Timely patching is critical for maintaining the operational availability, confidentiality, and integrity of information technology (IT) systems. However, failure to keep SLEM 5 and application soft...Rule Medium Severity -
SLEM 5 must use vlock to allow for session locking.
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...Rule Medium Severity -
SLEM 5 must not have the telnet-server package installed.
It is detrimental for SLEM 5 to provide, or install by default, functionality exceeding requirements or mission objectives. These unnecessary capabilities or services are often overlooked, and ther...Rule High Severity -
SLEM 5 file systems that are being imported via Network File System (NFS) must be mounted to prevent binary files from being executed.
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. Exe...Rule Medium Severity -
SLEM 5 file systems that are used with removable media must be mounted to prevent files with the setuid and setgid bit set from being executed.
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" ...Rule Medium Severity -
SLEM 5 file systems that contain user home directories must be mounted to prevent files with the setuid and setgid bit set from being executed.
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 se...Rule Medium Severity -
SLEM 5 must have system commands set to a mode of 755 or less permissive.
If SLEM 5 were to allow 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 ch...Rule Medium Severity -
SLEM 5 library files must be owned by root.
If SLEM 5 were to allow 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 ch...Rule Medium Severity -
SLEM 5 must have system commands group-owned by root or a system account.
If SLEM 5 were to allow 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 ch...Rule Medium Severity -
The sticky bit must be set on all SLEM 5 world-writable directories.
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 ...Rule Medium Severity -
SLEM 5 must generate error messages that provide information necessary for corrective actions without revealing information that could be exploited by adversaries.
Any operating system providing too much information in error messages risks compromising the data and security of the structure, and content of error messages needs to be carefully considered by th...Rule Medium Severity -
SLEM 5 clock must, for networked systems, be synchronized to an authoritative DOD time source at least every 24 hours.
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 condu...Rule Medium Severity -
SLEM 5 must not send Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirects.
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 r...Rule Medium Severity -
SLEM 5 must not allow interfaces to send Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages by default.
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 r...Rule Medium Severity -
SLEM 5 must be configured to use TCP syncookies.
Denial of service (DoS) is a condition in which a resource is not available for legitimate users. When this occurs, the organization either cannot accomplish its mission or must operate at degraded...Rule Medium Severity -
SLEM 5 must have SSH installed to protect the confidentiality and integrity of transmitted information.
Without protection of the transmitted information, confidentiality and integrity may be compromised because unprotected communications can be intercepted and either read or altered. This requirem...Rule High Severity -
SLEM 5 must use SSH to protect the confidentiality and integrity of transmitted information.
Without protection of the transmitted information, confidentiality and integrity may be compromised because unprotected communications can be intercepted and either read or altered. This requireme...Rule High Severity -
SLEM 5 must be configured so that all network connections associated with SSH traffic terminate after becoming unresponsive.
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 con...Rule Medium Severity -
SLEM 5 SSH daemon must disable forwarded remote X connections for interactive users, unless to fulfill documented and validated mission requirements.
The security risk of using X11 forwarding is that the client's X11 display server may be exposed to attack when the SSH client requests forwarding. A system administrator may have a stance in which...Rule Medium Severity -
SLEM 5 SSH daemon must be configured to only use Message Authentication Codes (MACs) employing FIPS 140-2/140-3 approved cryptographic hash algorithms.
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 auth...Rule High Severity -
SLEM 5 must log SSH connection attempts and failures to the server.
Remote access services, such as those providing remote access to network devices and information systems, which lack automated monitoring capabilities, increase risk and make remote user access man...Rule Medium Severity -
SLEM 5, for PKI-based authentication, must enforce authorized access to the corresponding private key.
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 use...Rule Medium Severity -
There must be no shosts.equiv files on SLEM 5.
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 do...Rule High Severity -
SLEM 5 wireless network adapters must be disabled unless approved and documented.
Without protection of communications with wireless peripherals, confidentiality and integrity may be compromised because unprotected communications can be intercepted and either read, altered, or u...Rule Medium Severity -
All SLEM 5 local interactive user home directories defined in the /etc/passwd file must exist.
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...Rule Medium Severity -
SLEM 5 must automatically expire temporary accounts within 72 hours.
Temporary accounts are privileged or nonprivileged accounts established during pressing circumstances, such as new software or hardware configuration or an incident response, where the need for pro...Rule Medium Severity -
SLEM 5 must not have unnecessary accounts.
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 a...Rule Medium Severity -
SLEM 5 must not have duplicate User IDs (UIDs) for interactive users.
To ensure accountability and prevent unauthenticated access, interactive users must be identified and authenticated to prevent potential misuse and compromise of the system. Interactive users incl...Rule Medium Severity -
SLEM 5 must initiate a session lock after a 15-minute period of inactivity.
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 temporar...Rule Medium Severity -
SLEM 5 must have policycoreutils package installed.
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 firmwar...Rule Low Severity -
SLEM 5 must require reauthentication when using the "sudo" command.
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, i...Rule Medium Severity -
SLEM 5 must specify the default "include" directory for the /etc/sudoers file.
The "sudo" command allows authorized users to run programs (including shells) as other users, system users, and root. The "/etc/sudoers" file is used to configure authorized "sudo" users as well as...Rule Medium Severity -
SLEM 5 must enforce passwords that contain at least one numeric character.
Use of a complex password helps 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 a...Rule Medium Severity -
SLEM 5 must not have accounts configured with blank or null passwords.
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.Rule High Severity -
SLEM 5 must employ user passwords with a minimum lifetime of 24 hours (one day).
Enforcing a minimum password lifetime helps prevent repeated password changes to defeat the password reuse or history enforcement requirement. If users are allowed to immediately and continually ch...Rule Medium Severity -
SLEM 5 must employ a password history file.
Password complexity, or strength, is a measure of the effectiveness of a password in resisting attempts at guessing and brute-force attacks. If the information system or application allows the user...Rule Medium Severity -
SLEM 5 must employ FIPS 140-2/140-3 approved cryptographic hashing algorithm for system authentication (login.defs).
Unapproved mechanisms that are used for authentication to the cryptographic module are not verified and therefore cannot be relied on to provide confidentiality or integrity, and DOD data may be co...Rule Medium Severity -
SLEM 5 must have the packages required for multifactor authentication to be installed.
Using an authentication device, such as a Common Access Card (CAC) or token separate from the information system, ensures that even if the information system is compromised, that compromise will no...Rule Medium Severity -
SLEM 5 must implement certificate status checking for multifactor authentication.
Using an authentication device, such as a Common Access Card (CAC) or token separate from the information system, ensures credentials stored on the authentication device will not be affected if the...Rule Medium Severity -
SLEM 5 must be configured to not overwrite Pluggable Authentication Modules (PAM) configuration on package changes.
The "pam-config" command line utility automatically generates a system PAM configuration as packages are installed, updated, or removed from the system. "pam-config" removes configurations for PAM ...Rule Medium Severity -
SLEM 5 must use a file integrity tool to verify correct operation of all security functions.
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 firmwa...Rule Medium Severity -
SLEM 5 must notify the system administrator (SA) when Advanced Intrusion Detection Environment (AIDE) discovers anomalies in the operation of any security functions.
If anomalies are not acted on, security functions may fail to secure the system. Security function is defined as the hardware, software, and/or firmware of the information system responsible for e...Rule Medium Severity -
SLEM 5 must have the auditing package installed.
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 ...Rule Medium Severity -
SLEM 5 must allocate audit record storage capacity to store at least one week of audit records when audit records are not immediately sent to a central audit record storage facility.
To ensure SLEM 5 has a sufficient storage capacity in which to write the audit logs, SLEM 5 must be able to allocate audit record storage capacity. The task of allocating audit record storage capa...Rule Medium Severity -
SLEM 5 audit system must take appropriate action when the audit storage volume is full.
It is critical that when SLEM 5 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, failure...Rule Medium Severity
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