4.1.18 Ensure the audit configuration is immutable (Scored)

Level 2 - Server 
Level 2 - Workstation

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.

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.

Run the following command and verify output matches:

# grep "^\s*[^#]" /etc/audit/audit.rules | tail -1 
-e 2

Add the following line to the end of the/etc/audit/audit.rules file.

-e 2