NixOS must enable the audit daemon.

Once an attacker establishes access to a system, the attacker often attempts to create a persistent method of reestablishing access. One way to accomplish this is for the attacker to create an account. Auditing account creation actions provides logging that can be used for forensic purposes.

Note: For the "security.audit.enable" configuration, both "true" and "lock" are valid values. The "true" value allows for loading of audit rules (synonymous with "-e 1" in audit rules), while the "lock" value loads audit rules and enforces that the rules cannot be changed without the system rebooting (synonymous with "-e 2"). Setting this value to "lock" is recommended to be performed as the final step in configuring the audit daemon.

Satisfies: SRG-OS-000004-GPOS-00004, SRG-OS-000254-GPOS-00095, SRG-OS-000344-GPOS-00135, SRG-OS-000348-GPOS-00136, SRG-OS-000349-GPOS-00137, SRG-OS-000350-GPOS-00138, SRG-OS-000351-GPOS-00139, SRG-OS-000352-GPOS-00140, SRG-OS-000353-GPOS-00141, SRG-OS-000354-GPOS-00142, SRG-OS-000122-GPOS-00063, SRG-OS-000358-GPOS-00145

Verify NixOS has the audit service configured with the following commands:

$ systemctl is-active audit.service active

$ systemctl is-active auditd.service active

If auditd and audit services are not active, this is a finding.

Configure NixOS to enable the audit service by updating the NixOS config, typically stored either in /etc/nixos/configuration.nix or /etc/nixos/flake.nix:

security.auditd.enable = true; security.audit.enable = true;

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