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

NixOS must enforce the limit of three consecutive invalid logon attempts by a user during a 15-minute time period.

DISA Rule

SV-268081r1130954_rule

Vulnerability Number

V-268081

Group Title

SRG-OS-000021-GPOS-00005

Rule Version

ANIX-00-000040

Severity

CAT II

CCI(s)

• CCI-000044 - Enforce the organization-defined limit of consecutive invalid logon attempts by a user during the organization-defined time period.
• CCI-002238 - Automatically lock the account or node for either an organization-defined time period, until the locked account or node is released by an administrator, or delays the next logon prompt according to the organization-defined delay algorithm when the maximum number of unsuccessful logon attempts is exceeded.
• CCI-000172 - Generate audit records for the event types defined in AU-2 c that include the audit record content defined in AU-3.

Weight

10

Fix Recommendation

Configure NixOS to lock an account when three unsuccessful logon attempts occur within 15 minutes.

Update the NixOS config, typically stored either in /etc/nixos/configuration.nix or /etc/nixos/flake.nix, to include the following lines:

security.pam.services = let pamfile = ''
auth required pam_faillock.so preauth silent audit deny=3 fail_interval=900 unlock_time=0
auth sufficient pam_unix.so nullok try_first_pass
auth [default=die] pam_faillock.so authfail audit deny=3 fail_interval=900 unlock_time=0
auth sufficient pam_faillock.so authsucc

account required pam_faillock.so
'';
in {
login.text = pkgs.lib.mkDefault pamfile;
sshd.text = pkgs.lib.mkDefault pamfile;
};

Note that the entire pam file must be entered as this pamfile string.

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

Check Contents

Verify that NixOS locks an account after three unsuccessful logon attempts within 15 minutes with the following commands:

$ cat /etc/pam.d/login

auth required pam_faillock.so preauth deny=3 even_deny_root fail_interval=900 unlock_time=0 dir=/var/log/faillock

If the "fail_interval" option is not set to "900" or less (but not "0") on the "preauth" lines with the "pam_faillock" module, or is missing from this line, this is a finding.

Vulnerability Number

V-268081

Documentable

False

Rule Version

ANIX-00-000040

Severity Override Guidance

Verify that NixOS locks an account after three unsuccessful logon attempts within 15 minutes with the following commands:

$ cat /etc/pam.d/login

auth required pam_faillock.so preauth deny=3 even_deny_root fail_interval=900 unlock_time=0 dir=/var/log/faillock

If the "fail_interval" option is not set to "900" or less (but not "0") on the "preauth" lines with the "pam_faillock" module, or is missing from this line, this is a finding.

Check Content Reference

M

Target Key

5658