STIGQter: STIG Summary: Anduril NixOS Security Technical Implementation Guide Version: 1 Release: 2 Benchmark Date: 01 Oct 2025:

NixOS must notify the system administrator (SA) and information system security officer (ISSO) (at a minimum) when allocated audit record storage volume reaches 75 percent utilization.

DISA Rule

SV-268101r1131004_rule

Vulnerability Number

V-268101

Group Title

SRG-OS-000046-GPOS-00022

Rule Version

ANIX-00-000400

Severity

CAT II

CCI(s)

• CCI-000139 - Alert organization-defined personnel or roles within an organization-defined time period in the event of an audit logging process failure.
• CCI-001855 - Provide a warning to organization-defined personnel, roles, and/or locations within an organization-defined time period when allocated audit log storage volume reaches an organization-defined percentage of repository maximum audit log storage capacity.

Weight

10

Fix Recommendation

Configure NixOS 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.

If the space_left_action parameter is set to "syslog", make sure the event being logged generates a notification to the SA and ISSO.

If the space_left_action parameter is set to "exec", make sure the command being executed notifies the SA and ISSO.

If the space_left_action parameter is set to "email", set the action_mail_acct parameter to an email address for the SA and ISSO.

Add the following Nix code to the NixOS Configuration, usually located in /etc/nixos/configuration.nix or /etc/nixos/flake.nix:

space_left_action = syslog

For example, an updated configuration of 'environment.etc."audit/auditd.conf".text' would look like the following ('...' denoting that the 'environment.etc."audit/auditd.conf".text' configuration may have other options configured):

environment.etc."audit/auditd.conf".text = [
''
...
space_left_action = syslog
...
''
];

Rebuild and switch to the new NixOS configuration:
$ sudo nixos-rebuild switch

Check Contents

Verify NixOS 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 command:

$ sudo grep -w space_left_action /etc/audit/auditd.conf

space_left_action = syslog

If the "space_left_action" parameter is missing, commented out, or set to blanks, this is a finding.

If the "space_left_action" is set to "syslog", the system logs the event, but does not generate a notification, this is a finding.

If the "space_left_action" is set to "exec", the system executes a designated script. If this script does not inform the SA of the event, this is a finding.

If the "space_left_action" is set to "email" check the value of the "action_mail_acct" parameter with the following command:

$ sudo grep action_mail_acct /etc/audit/auditd.conf

action_mail_acct root@localhost

The "action_mail_acct" parameter, if missing, defaults to "root". If the "action_mail_acct" parameter is not set to the email address of the SA and/or ISSO, this is a finding.

Note: If the email address of the SA is on a remote system, a mail package must be available.

Vulnerability Number

V-268101

Documentable

False

Rule Version

ANIX-00-000400

Severity Override Guidance

Verify NixOS 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 command:

$ sudo grep -w space_left_action /etc/audit/auditd.conf

space_left_action = syslog

If the "space_left_action" parameter is missing, commented out, or set to blanks, this is a finding.

If the "space_left_action" is set to "syslog", the system logs the event, but does not generate a notification, this is a finding.

If the "space_left_action" is set to "exec", the system executes a designated script. If this script does not inform the SA of the event, this is a finding.

If the "space_left_action" is set to "email" check the value of the "action_mail_acct" parameter with the following command:

$ sudo grep action_mail_acct /etc/audit/auditd.conf

action_mail_acct root@localhost

The "action_mail_acct" parameter, if missing, defaults to "root". If the "action_mail_acct" parameter is not set to the email address of the SA and/or ISSO, this is a finding.

Note: If the email address of the SA is on a remote system, a mail package must be available.

Check Content Reference

M

Target Key

5658