Ensure no duplicate GIDs exist

MediumLevel 1Automatedfreebsd

Description

Although the pw program will not let you create a duplicate Group ID (GID), it is possible for an administrator to manually edit the /etc/group file and change the GID field. User groups must be assigned unique GIDs for accountability and to ensure appropriate access protections. Audit: automated read-only check derived from the CIS audit procedure; it prints "compliant" when the control is met.

How it is checked

Audit method: Shell command

shell

command -v cut >/dev/null 2>&1 || exit 1; out=$( { cut -d: -f3 /etc/group | sort -n | uniq -d ; } 2>/dev/null ); [ -z "$out" ] && echo compliant || printf '%s\n' "$out" | head -n 20

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Based on the audit script's results, establish unique GIDs and review all files owned by the shared GID to determine which group they are supposed to belong to.

Properties

Operating systems: Any
Tags: freebsdaccounts
Reference: CIS FreeBSD 14 Benchmark v1.0.1 - 6.2.5 Ensure no duplicate GIDs exist

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target freebsd