Australian Cyber Security Centre (ACSC) Essential Eight
Rules and Groups employed by this XCCDF Profile
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Record attempts to alter time through adjtimex
If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default),...Rule Medium Severity -
Record Attempts to Alter Time Through clock_settime
If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default),...Rule Medium Severity -
Record attempts to alter time through settimeofday
If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default),...Rule Medium Severity -
Record Attempts to Alter Time Through stime
If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default),...Rule Medium Severity -
Record Attempts to Alter the localtime File
If the <code>auditd</code> daemon is configured to use the <code>augenrules</code> program to read audit rules during daemon startup (the default),...Rule Medium Severity -
Configure auditd Data Retention
The audit system writes data to <code>/var/log/audit/audit.log</code>. By default, <code>auditd</code> rotates 5 logs by size (6MB), retaining a ma...Group -
Configure auditd flush priority
The <code>auditd</code> service can be configured to synchronously write audit event data to disk. Add or correct the following line in <code>/etc/...Rule Medium Severity -
Set number of records to cause an explicit flush to audit logs
To configure Audit daemon to issue an explicit flush to disk command after writing <xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_aud...Rule Medium Severity -
Include Local Events in Audit Logs
To configure Audit daemon to include local events in Audit logs, set <code>local_events</code> to <code>yes</code> in <code>/etc/audit/auditd.conf<...Rule Medium Severity -
Resolve information before writing to audit logs
To configure Audit daemon to resolve all uid, gid, syscall, architecture, and socket address information before writing the events to disk, set <co...Rule Low Severity -
Set type of computer node name logging in audit logs
To configure Audit daemon to use a unique identifier as computer node name in the audit events, set <code>name_format</code> to <code><xccdf-1.2:su...Rule Medium Severity -
Write Audit Logs to the Disk
To configure Audit daemon to write Audit logs to the disk, set <code>write_logs</code> to <code>yes</code> in <code>/etc/audit/auditd.conf</code>. ...Rule Medium Severity -
Configure Syslog
The syslog service has been the default Unix logging mechanism for many years. It has a number of downsides, including inconsistent log format, lac...Group -
Ensure rsyslog is Installed
Rsyslog is installed by default. Thersyslogpackage can be installed with the following command:$ sudo yum install rsyslog
Rule Medium Severity -
Enable rsyslog Service
The <code>rsyslog</code> service provides syslog-style logging by default on Red Hat Enterprise Linux 7. The <code>rsyslog</code> service can be e...Rule Medium Severity -
Network Configuration and Firewalls
Most systems must be connected to a network of some sort, and this brings with it the substantial risk of network attack. This section discusses th...Group -
Ensure System is Not Acting as a Network Sniffer
The system should not be acting as a network sniffer, which can capture all traffic on the network to which it is connected. Run the following to d...Rule Medium Severity -
firewalld
The dynamic firewall daemon <code>firewalld</code> provides a dynamically managed firewall with support for network “zones” to assign a level of tr...Group -
Inspect and Activate Default firewalld Rules
Firewalls can be used to separate networks into different zones based on the level of trust the user has decided to place on the devices and traffi...Group -
Install firewalld Package
Thefirewalldpackage can be installed with the following command:$ sudo yum install firewalld
Rule Medium Severity -
Verify firewalld Enabled
Thefirewalldservice can be enabled with the following command:$ sudo systemctl enable firewalld.service
Rule Medium Severity -
File Permissions and Masks
Traditional Unix security relies heavily on file and directory permissions to prevent unauthorized users from reading or modifying files to which t...Group -
Verify Permissions on Important Files and Directories
Permissions for many files on a system must be set restrictively to ensure sensitive information is properly protected. This section discusses impo...Group -
Verify that All World-Writable Directories Have Sticky Bits Set
When the so-called 'sticky bit' is set on a directory, only the owner of a given file may remove that file from the directory. Without the sticky b...Rule Medium Severity -
Ensure All SGID Executables Are Authorized
The SGID (set group id) bit should be set only on files that were installed via authorized means. A straightforward means of identifying unauthoriz...Rule Medium Severity -
Ensure All SUID Executables Are Authorized
The SUID (set user id) bit should be set only on files that were installed via authorized means. A straightforward means of identifying unauthorize...Rule Medium Severity -
Ensure No World-Writable Files Exist
It is generally a good idea to remove global (other) write access to a file when it is discovered. However, check with documentation for specific a...Rule Medium Severity -
Verify File Permissions Within Some Important Directories
Some directories contain files whose confidentiality or integrity is notably important and may also be susceptible to misconfiguration over time, p...Group -
Verify that System Executables Have Root Ownership
System executables are stored in the following directories by default: <pre>/bin /sbin /usr/bin /usr/libexec /usr/local/bin /usr/local/sbin /usr/sb...Rule Medium Severity -
Verify that Shared Library Files Have Root Ownership
System-wide shared library files, which are linked to executables during process load time or run time, are stored in the following directories by ...Rule Medium Severity -
Verify that System Executables Have Restrictive Permissions
System executables are stored in the following directories by default: <pre>/bin /sbin /usr/bin /usr/libexec /usr/local/bin /usr/local/sbin /usr/sb...Rule Medium Severity -
Verify that Shared Library Files Have Restrictive Permissions
System-wide shared library files, which are linked to executables during process load time or run time, are stored in the following directories by ...Rule Medium Severity -
Restrict Partition Mount Options
System partitions can be mounted with certain options that limit what files on those partitions can do. These options are set in the <code>/etc/fst...Group -
Add nodev Option to /dev/shm
The <code>nodev</code> mount option can be used to prevent creation of device files in <code>/dev/shm</code>. Legitimate character and block device...Rule Medium Severity -
Add noexec Option to /dev/shm
The <code>noexec</code> mount option can be used to prevent binaries from being executed out of <code>/dev/shm</code>. It can be dangerous to allow...Rule Medium Severity -
Add nosuid Option to /dev/shm
The <code>nosuid</code> mount option can be used to prevent execution of setuid programs in <code>/dev/shm</code>. The SUID and SGID permissions s...Rule Medium Severity -
Restrict Programs from Dangerous Execution Patterns
The recommendations in this section are designed to ensure that the system's features to protect against potentially dangerous program execution ar...Group -
Restrict Access to Kernel Message Buffer
To set the runtime status of the <code>kernel.dmesg_restrict</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.dmesg...Rule Low Severity -
Disable Kernel Image Loading
To set the runtime status of the <code>kernel.kexec_load_disabled</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel....Rule Medium Severity -
Restrict usage of ptrace to descendant processes
To set the runtime status of the <code>kernel.yama.ptrace_scope</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.ya...Rule Medium Severity -
Enable ExecShield
ExecShield describes kernel features that provide protection against exploitation of memory corruption errors such as buffer overflows. These featu...Group -
Enable ExecShield via sysctl
By default on Red Hat Enterprise Linux 7 64-bit systems, ExecShield is enabled and can only be disabled if the hardware does not support ExecShield...Rule Medium Severity -
Restrict Exposed Kernel Pointer Addresses Access
To set the runtime status of the <code>kernel.kptr_restrict</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.kptr_r...Rule Medium Severity -
Enable Randomized Layout of Virtual Address Space
To set the runtime status of the <code>kernel.randomize_va_space</code> kernel parameter, run the following command: <pre>$ sudo sysctl -w kernel.r...Rule Medium Severity -
SELinux
SELinux is a feature of the Linux kernel which can be used to guard against misconfigured or compromised programs. SELinux enforces the idea that p...Group -
Configure SELinux Policy
The SELinux <code>targeted</code> policy is appropriate for general-purpose desktops and servers, as well as systems in many other roles. To config...Rule Medium Severity -
Ensure SELinux State is Enforcing
The SELinux state should be set to <code><xccdf-1.2:sub idref="xccdf_org.ssgproject.content_value_var_selinux_state" use="legacy"></xccdf-1.2:sub><...Rule High Severity -
Services
The best protection against vulnerable software is running less software. This section describes how to review the software which Red Hat Enterpris...Group -
Avahi Server
The Avahi daemon implements the DNS Service Discovery and Multicast DNS protocols, which provide service and host discovery on a network. It allows...Group -
Disable Avahi Server if Possible
Because the Avahi daemon service keeps an open network port, it is subject to network attacks. Disabling it can reduce the system's vulnerability t...Group
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