Vulnerability Discussion

If action is not taken when storage volume reaches 95 percent utilization, the auditing system may fail when the storage volume reaches capacity.

While "%" is fully compliant for auditd.conf, you must account for how auditd processes it. The percentage-to-megabyte conversion occurs only when the audit daemon starts. If you dynamically resize the underlying logical volume/partition where /var/log/audit resides while the system is running, the daemon will not automatically know. You must reload it to trigger a recalculation.

Check

Verify RHEL 9 takes action when allocated audit record storage volume reaches 95 percent of the repository maximum audit record storage capacity with the following command:

$ sudo grep -w admin_space_left /etc/audit/auditd.conf
admin_space_left = 5%

If the value of the "admin_space_left" keyword is not set to 5 percent of the storage volume allocated to audit logs, or if the line is commented out, ask the system administrator (SA) to indicate how the system is taking action if the allocated storage is about to reach capacity. If the "space_left" value is not configured to the correct value, this is a finding.

Fix

Configure RHEL 9 to initiate an action when allocated audit record storage volume reaches 95 percent of the repository maximum audit record storage capacity by adding/modifying the following line in the /etc/audit/auditd.conf file.

admin_space_left = 5%