4.1.19 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.

Rationale:

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

Notes:

This setting will ensure reloading the auditd config to set active settings requires a system
reboot.

See Also

https://workbench.cisecurity.org/files/2420