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CIS Ubuntu 14.04 LTS - 6.1.3 Ensure permissions on /etc/shadow are configured

DevOps & Security
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Verify /etc/shadow has correct ownership (root:shadow) and permissions (640 or more restrictive)

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Source SKILL.md: https://github.com/CyberStrikeus/CyberStrike/blob/HEAD/.cyberstrike/skill/CIS_benchmarks/Operating_Systems/Ubuntu/CIS_Ubuntu_Linux_14.04_LTS_Benchmark_v2.1.0/cis-ubuntu1404-v210-6-1-3/SKILL.md

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6.1.3 Ensure permissions on /etc/shadow are configured (Scored)

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

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

stat /etc/shadow

Expected Result

Access: (0640/-rw-r-----)  Uid: (    0/    root)   Gid: (   42/  shadow)

Remediation

Run the following commands to set permissions on /etc/shadow:

chown root:shadow /etc/shadow
chmod o-rwx,g-wx /etc/shadow

Default Value

Access: (0640/-rw-r-----) Uid: ( 0/ root) Gid: ( 42/ shadow)

References

None

CIS Controls

16.14 Encrypt/Hash All Authentication Files And Monitor Their Access - Verify that all authentication files are encrypted or hashed and that these files cannot be accessed without root or administrator privileges. Audit all access to password files in the system.

Profile

  • Level 1