Profile Applicability:
Level 1

Description:
 The /etc/shadow- file is a backup of the /etc/shadow file, which contains users’ encrypted password information. Improper permissions on this backup file can expose sensitive password hashes to unauthorized users.

Rationale:
 Securing permissions on /etc/shadow- protects sensitive password data from unauthorized access, reducing the risk of credential compromise.

Impact:
 Pros:

  • Prevents unauthorized access to password backups.

  • Maintains integrity of user authentication data.

Cons:

  • Overly restrictive permissions may impact backup and restore operations.

Default Value:
 Permissions may vary by distribution, but should be restrictive.

Pre-requisites:

  • Root or sudo privileges to audit and modify file permissions.

Remediation:

Test Plan:

Using Linux command line:

  1. Check current permissions of /etc/shadow-:

    ls -l /etc/shadow-

  2. Verify ownership is root:root and permissions are set to 600 or more restrictive.

Implementation Plan:

Using Linux command line:

  1. Set ownership to root:

    chown root:root /etc/shadow-

  2. Set permissions to 600:

    chmod 600 /etc/shadow-

  3. Verify changes:

    ls -l /etc/shadow-

Backout Plan:

Using Linux command line:

  1. Restore previous permissions and ownership from backup if necessary.

  2. Confirm system utilities operate correctly after changes.

References: