cis-ubuntu2004-v300-7-1-4

name	cis-ubuntu2004-v300-7-1-4
description	Ensure access to /etc/group- is configured
category	cis-iam
version	3.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-20.04","file-permissions"]
cis_id	7.1.4
cis_benchmark	CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

7.1.4 Ensure access to /etc/group- is configured (Automated)

Profile

• Level 1 - Server
• Level 1 - Workstation

Description

The /etc/group- file contains a backup list of all the valid groups defined in the system.

Rationale

It is critical to ensure that the /etc/group- file is protected from unauthorized access. Although it is protected by default, the file permissions could be changed either inadvertently or through malicious actions.

Impact

None

Audit Procedure

Command Line

Run the following command to verify /etc/group- is mode 644 or more restrictive, Uid is 0/root and Gid is 0/root:

# stat -Lc 'Access: (%#a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/group-

Expected Result

Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)

Remediation

Command Line

Run the following commands to remove excess permissions, set owner, and set group on /etc/group-:

# chmod u-x,go-wx /etc/group-
# chown root:root /etc/group-

Default Value

Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)

References

1. NIST SP 800-53 Rev. 5: AC-3. MP-2

CIS Controls

Controls Version	Control	IG 1	IG 2	IG 3
v8	3.3 Configure Data Access Control Lists	X	X	X
v7	14.6 Protect Information through Access Control Lists	X	X	X

MITRE ATT&CK Mappings:

Techniques / Sub-techniques	Tactics	Mitigations
T1003, T1003.008, T1222, T1222.002	TA0005	M1022