cis-ubuntu1804-v220-6-1-4

name	cis-ubuntu1804-v220-6-1-4
description	Ensure permissions on /etc/group- are configured
category	cis-iam
version	2.2.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-18.04","file-permissions"]
cis_id	6.1.4
cis_benchmark	CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

6.1.4 Ensure permissions on /etc/group- are 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.

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

• v8: 3.3 Configure Data Access Control Lists
• v7: 14.6 Protect Information through Access Control Lists