======6.2.20 Ensure shadow group is empty (Scored)====== =====Profile Applicability===== Level 1 - Server Level 1 - Workstation =====Description===== The shadow group allows system programs which require access the ability to read the ''/etc/shadow'' file. No users should be assigned to the shadow group. =====Rationale===== Any users assigned to the shadow group would be granted read access to the /etc/shadow file. If attackers can gain read access to the ''/etc/shadow'' file, they can easily run a password cracking program against the hashed passwords to break them. Other security information that is stored in the ''/etc/shadow'' file (such as expiration) could also be useful to subvert additional user accounts. =====Audit===== Run the following script and verify no results are returned: # grep ^shadow:[^:]*:[^:]*:[^:]+ /etc/group # awk -F: '($4 == "") { print }' /etc/passwd =====Remediation===== Remove all users from the shadow group, and change the primary group of any users with shadow as their primary group.