Verify Permissions on Backup shadow File

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Description

To properly set the permissions of /etc/shadow-, run the command:

$ sudo chmod 0640 /etc/shadow-

Rationale

The /etc/shadow- file is a backup file of /etc/shadow, and as such, it contains the list of local system accounts and password hashes. Protection of this file is critical for system security.

Remediation

Shell script

The following script can be run on the host to remediate the issue.

#!/bin/bash

chmod u-xs,g-xws,o-xwrt /etc/shadow-

Ansible playbook

The following playbook can be run with Ansible to remediate the issue.

- name: Test for existence /etc/shadow-
  stat:
    path: /etc/shadow-
  register: file_exists
  tags:
  - NIST-800-53-AC-6 (1)
  - PCI-DSS-Req-8.7.c
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_permissions_backup_etc_shadow
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed

- name: Ensure permission u-xs,g-xws,o-xwrt on /etc/shadow-
  file:
    path: /etc/shadow-
    mode: u-xs,g-xws,o-xwrt
  when: file_exists.stat is defined and file_exists.stat.exists
  tags:
  - NIST-800-53-AC-6 (1)
  - PCI-DSS-Req-8.7.c
  - PCI-DSSv4-2.2.6
  - configure_strategy
  - file_permissions_backup_etc_shadow
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed