RHEL 8 must notify the System Administrator (SA) and Information System Security Officer (ISSO) (at a minimum) when allocated audit record storage volume reaches 75 percent of the repository maximum audit record storage capacity.
If security personnel are not notified immediately when storage volume reaches 75 percent utilization, they are unable to plan for audit record storage capacity expansion.
Check
Verify RHEL 8 notifies the SA and ISSO (at a minimum) when allocated audit record storage volume reaches 75 percent of the repository maximum audit record storage capacity with the following commands:
$ sudo grep space_left /etc/audit/auditd.conf
space_left = 25% space_left_action = email
If the value of the "space_left" keyword is not set to "25%" and the "space_left_action" is not set to "email", or if these lines are commented out, ask the System Administrator to indicate how the system is providing real-time alerts to the SA and ISSO.
If there is no evidence that real-time alerts are configured on the system, this is a finding.
Fix
Configure the operating system to initiate an action to notify the SA and ISSO (at a minimum) when allocated audit record storage volume reaches 75 percent of the repository maximum audit record storage capacity by adding/modifying the following lines in the /etc/audit/auditd.conf file.
space_left = 25% space_left_action = email
Note: Option names and values in the auditd.conf file are case insensitive.