NixOS must remove all software components after updated versions have been installed.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-268162	ANIX-00-001680	SV-268162r1039374_rule		Medium

Description

Previous versions of software components that are not removed from the information system after updates have been installed may be exploited by adversaries. Some information technology products may remove older versions of software automatically from the information system.

STIG	Date
Anduril NixOS Security Technical Implementation Guide	2024-10-25

Details

Check Text (C-72086r1039372_chk)

Verify NixOS removes all software components after updated versions have been installed by reviewing /etc/nixos/configuration.nix and remove any references to outdated versions of nixpkgs.

If any outdated versions of nixpkgs are present in the configuration.nix file, this is a finding.

Fix Text (F-71989r1039373_fix)

After updating NixOS (either via "cd /etc/nixos; sudo nix flake update; sudo nixos-rebuild switch" or "sudo nixos-rebuild switch –upgrade"), reboot the system to ensure all running software comes from the current active NixOS generation.

Edit /etc/nixos/configuration.nix and remove any references to outdated versions of nixpkgs.