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CIS Ubuntu 14.04 LTS - 6.1.7 Ensure permissions on /etc/shadow- are configured

DevOps & Security
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Verify /etc/shadow- has correct ownership 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-v210-6-1-7/SKILL.md

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6.1.7 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 backup information about user accounts that is critical to the security of those accounts, such as the hashed password and other security information.

Rationale

It is critical to ensure that the /etc/shadow- 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

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: (   42/  shadow)

Remediation

Run the one of the following chown commands as appropriate and the chmod to set permissions on /etc/shadow-:

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

chmod o-rwx,g-rw /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