The operating system must provide an immediate warning to the SA and ISSO (at a minimum) when allocated audit record storage volume reaches 75% of repository maximum audit record storage capacity.

From Apple OS X 10.11 Security Technical Implementation Guide

Associated with: CCI-001855

SV-82005r1_rule The operating system must provide an immediate warning to the SA and ISSO (at a minimum) when allocated audit record storage volume reaches 75% of repository maximum audit record storage capacity.

Vulnerability discussion

The audit service must be configured to require a minimum percentage of free disk space in order to run. This ensures that audit will notify the administrator that action is required to free up more disk space for audit logs.When minfree is set to 25%, security personnel are notified immediately when the storage volume is 75% full and are able to plan for audit record storage capacity expansion.

Check content

The check displays the "% free" to leave available for the system. The audit system will not write logs if the volume has less than this percentage of free disk space. To view the current setting, run the following command: /usr/bin/sudo /usr/bin/grep ^minfree /etc/security/audit_control If this returns no results, or does not contain "25", this is a finding.

Fix text

Edit the /etc/security/audit_control file, and change the value for "minfree" to "25". Use the following command to set the "minfree" value to "25%": /usr/bin/sudo /usr/bin/sed -i.bak 's/.*minfree.*/minfree:25/' /etc/security/audit_control; /usr/bin/sudo /usr/sbin/audit -s A text editor may also be used to implement the required updates to the /etc/security/audit_control file.

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