NixOS must take action when allocated audit record storage volume reaches 75 percent of the repository maximum audit record storage capacity.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-268103 | ANIX-00-000420 | SV-268103r1131008_rule | CCI-000139 | medium |
| Description | ||||
| 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. | ||||
| STIG | Date | |||
| Anduril NixOS Security Technical Implementation Guide | 2025-08-19 | |||
Details
Check Text (C-268103r1131008_chk)
Verify NixOS takes action when allocated audit record storage volume reaches 75 percent of the repository maximum audit record storage capacity with the following commands:
$ sudo grep -w space_left /etc/audit/auditd.conf
space_left = 25%
If the value of the "space_left" keyword is not set to "25%" or if the line is commented out, this is a finding.
Fix Text (F-71930r1131007_fix)
Configure the operating system to initiate an action to 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.
Add the following Nix code to the NixOS Configuration, usually located in /etc/nixos/configuration.nix or /etc/nixos/flake.nix:
environment.etc."audit/auditd.conf".text = [
''
space_left = 25%
''
];
Rebuild and switch to the new NixOS configuration:
$ sudo nixos-rebuild switch