4.1.3.20 Ensure the audit configuration is immutable

Information

Set system audit so that audit rules cannot be modified with auditctl Setting the flag "-e 2" forces audit to be put in immutable mode. Audit changes can only be made on system reboot.

Note: This setting will require the system to be rebooted to update the active auditd configuration settings.

In immutable mode, unauthorized users cannot execute changes to the audit system to potentially hide malicious activity and then put the audit rules back. Users would most likely notice a system reboot and that could alert administrators of an attempt to make unauthorized audit changes.

Solution

Edit or create the file /etc/audit/rules.d/99-finalize.rules and add the line -e 2 at the end of the file:

Example:

# printf -- "-e 2" >> /etc/audit/rules.d/99-finalize.rules

Load audit rules

Merge and load the rules into active configuration:

# augenrules --load

Check if reboot is required.

# if [[ $(auditctl -s | grep "enabled") =~ "2" ]]; then printf "Reboot required to load rules
"; fi

See Also

https://workbench.cisecurity.org/files/4239