cis-ubuntu2004-v300-7-2-8

name	cis-ubuntu2004-v300-7-2-8
description	Ensure no duplicate group names exist
category	cis-iam
version	3.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-20.04","groups"]
cis_id	7.2.8
cis_benchmark	CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

7.2.8 Ensure no duplicate group names exist (Automated)

Profile

• Level 1 - Server
• Level 1 - Workstation

Description

Although the groupadd program will not let you create a duplicate group name, it is possible for an administrator to manually edit the /etc/group file and change the group name.

Rationale

If a group is assigned a duplicate group name, it will create and have access to files with the first GID for that group in /etc/group. Effectively, the GID is shared, which is a security problem.

Impact

None

Audit Procedure

Command Line

Run the following script and verify no results are returned:

#!/usr/bin/env bash

{
    while read -r l_count l_group; do
        if [ "$l_count" -gt 1 ]; then
            echo -e "Duplicate Group: \"$l_group\" Groups: \"$(awk -F: '($1 == n) { print $1 }' n=$l_group /etc/group | xargs)\""
        fi
    done < <(cut -f1 -d":" /etc/group | sort -n | uniq -c)
}

Expected Result

No output should be returned.

Remediation

Command Line

Based on the results of the audit script, establish unique names for the user groups. File group ownerships will automatically reflect the change as long as the groups have unique GIDs.

Default Value

N/A

References

1. NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	0.0 Explicitly Not Mapped