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cis-ubuntu1804-v220-6-1-7

DevOps & Security
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Ensure permissions on /etc/gshadow are configured

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Source SKILL.md: https://github.com/CyberStrikeus/CyberStrike/blob/HEAD/.cyberstrike/skill/CIS_benchmarks/Operating_Systems/Ubuntu/CIS_Ubuntu_Linux_18.04_LTS_Benchmark_v2.2.0/cis-ubuntu1804-v220-6-1-7/SKILL.md

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6.1.7 Ensure permissions on /etc/gshadow are configured (Automated)

Profile

  • Level 1 - Server
  • Level 1 - Workstation

Description

The /etc/gshadow file is used to store the information about groups 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/gshadow 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/gshadow file (such as group administrators) could also be useful to subvert the group.

Audit Procedure

Command Line

Run the following command to verify /etc/gshadow is mode 640 or more restrictive, Uid is 0/root and Gid is 0/root or {GID}/shadow:

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

Expected Result

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

Remediation

Command Line

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

# chown root:shadow /etc/gshadow
  -OR-
# chown root:root /etc/gshadow

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

# chmod u-x,g-wx,o-rwx /etc/gshadow

Default Value

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

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