cis-ubuntu1604-v200-6-1-6

name	cis-ubuntu1604-v200-6-1-6
description	Ensure permissions on /etc/shadow are configured
category	cis-storage
version	2.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-16.04","file-permissions","maintenance"]
cis_id	6.1.6
cis_benchmark	CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - 6.1.6

Profile Applicability

• Level 1 - Server
• Level 1 - Workstation

Description

The /etc/shadow file is used to store the information about user accounts that is critical to the security of those accounts, such as the hashed password and other security information.

Rationale

If attackers can gain read access to the /etc/shadow file, they can easily run a password cracking program against the hashed password to break it. Other security information that is stored in the /etc/shadow file (such as expiration) could also be useful to subvert the user accounts.

Audit Procedure

Command Line

Run the following command and verify Uid is 0/root, Gid is 0/root or <gid>/shadow, and Access is 640 or more restrictive:

stat /etc/shadow

Expected Result

Access: (0640/-rw-r-----)  Uid: (    0/    root)   Gid: (    0/    root)

Remediation

Command Line

Run one of the following commands to set ownership of /etc/shadow to root and group to either root or shadow:

chown root:root /etc/shadow
chown root:shadow /etc/shadow

Run the following command to remove excess permissions from /etc/shadow:

chmod u-x,g-wx,o-rwx /etc/shadow

Default Value

Access: (0640/-rw-r-----) Uid: ( 0/ root) Gid: ( 0/ root)

References

1. CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0

CIS Controls

Controls Version	Control
v7	16.4 Encrypt or Hash all Authentication Credentials Encrypt or hash with a salt all authentication credentials when stored.

Assessment Status

Automated