NixOS must notify designated personnel if baseline configurations are changed in an unauthorized manner.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-268153	SRG-OS-000363-GPOS-00150	ANIX-00-001460	SV-268153r1039347_rule	2024-10-25	1

Description
Unauthorized changes to the baseline configuration could make the system vulnerable to various attacks or allow unauthorized access to the operating system. Changes to operating system configurations can have unintended side effects, some of which may be relevant to security. Detecting such changes and providing an automated response can help avoid unintended, negative consequences that could ultimately affect the security state of the operating system. The operating system's IMO/ISSO and SAs must be notified via email and/or monitoring system trap when there is an unauthorized modification of a configuration item. Satisfies: SRG-OS-000363-GPOS-00150, SRG-OS-000445-GPOS-00199, SRG-OS-000446-GPOS-00200, SRG-OS-000447-GPOS-00201

Description

Unauthorized changes to the baseline configuration could make the system vulnerable to various attacks or allow unauthorized access to the operating system. Changes to operating system configurations can have unintended side effects, some of which may be relevant to security. Detecting such changes and providing an automated response can help avoid unintended, negative consequences that could ultimately affect the security state of the operating system. The operating system's IMO/ISSO and SAs must be notified via email and/or monitoring system trap when there is an unauthorized modification of a configuration item. Satisfies: SRG-OS-000363-GPOS-00150, SRG-OS-000445-GPOS-00199, SRG-OS-000446-GPOS-00200, SRG-OS-000447-GPOS-00201

ℹ️ Check
Verify NixOS notifies if baseline configurations are changed with Advanced Intrusion Detection Environment with the following commands: $ nix-store --query --requisites /run/current-system \| cut -d- -f2- \| sort \| uniq \| grep aide aide-0.18.6 etc-aide.conf $ cat /etc/nixos/configuration.nix \| grep -A 5 aide.conf If aide is not installed and is not configured to alert on file system changes, this is a finding.

ℹ️ Check

Verify NixOS notifies if baseline configurations are changed with Advanced Intrusion Detection Environment with the following commands: $ nix-store --query --requisites /run/current-system | cut -d- -f2- | sort | uniq | grep aide aide-0.18.6 etc-aide.conf $ cat /etc/nixos/configuration.nix | grep -A 5 aide.conf If aide is not installed and is not configured to alert on file system changes, this is a finding.

✔️ Fix
Configure /etc/nixos/configuration.nix to notify when baseline configuration changes by adding the following configuration settings: nixpkgs.overlays = [ (final: prev: { aide = prev.aide.overrideAttrs (old: { configureFlags = (old.configureFlags or [ ]) ++ [ "--sysconfdir=/etc" ]; }); }) ]; environment.systemPackages = [ pkgs.aide ]; environment.etc = { # Creates /etc/aide.conf "aide.conf" = { text = '' <CONFIG_TEXT> ''; mode = "0444"; }; }; services.cron = { enable = true; systemCronJobs = [ "00 0 * * 0\troot\taide -c /etc/aide.conf --check \| /bin/mail -s "aide integrity check run for ${config.networking.hostName}" root@notareal.email" ]; };

✔️ Fix

Configure /etc/nixos/configuration.nix to notify when baseline configuration changes by adding the following configuration settings: nixpkgs.overlays = [ (final: prev: { aide = prev.aide.overrideAttrs (old: { configureFlags = (old.configureFlags or [ ]) ++ [ "--sysconfdir=/etc" ]; }); }) ]; environment.systemPackages = [ pkgs.aide ]; environment.etc = { # Creates /etc/aide.conf "aide.conf" = { text = '' <CONFIG_TEXT> ''; mode = "0444"; }; }; services.cron = { enable = true; systemCronJobs = [ "00 0 * * 0\troot\taide -c /etc/aide.conf --check | /bin/mail -s "aide integrity check run for ${config.networking.hostName}" root@notareal.email" ]; };