cyberstrikeus 5.4.2.2 Ensure root is the only GID 0 account (Automated)
Profile
- Level 1 - Server
- Level 1 - Workstation
Description
The usermod command can be used to specify which group the root account belongs to. This affects permissions of files that are created by the root account.
Rationale
Using GID 0 for the root account helps prevent root-owned files from accidentally becoming accessible to non-privileged users.
Audit Procedure
Command Line
Run the following command to verify the root user's primary GID is 0, and no other user's have GID 0 as their primary GID:
# awk -F: '($1 !~ /^(sync|shutdown|halt|operator)/ && $4=="0") {print $1":"$4}' /etc/passwd
Expected Result
root:0
Note: User's: sync, shutdown, halt, and operator are excluded from the check for other user's with GID 0
Remediation
Command Line
Run the following command to set the root user's GID to 0:
# usermod -g 0 root
Run the following command to set the root group's GID to 0:
# groupmod -g 0 root
Remove any users other than the root user with GID 0 or assign them a new GID if appropriate.
Default Value
None specified.
References
- NIST SP 800-53 Rev. 5: CM-1, CM-2, CM-6, CM-7, IA-5
CIS Controls
v8 - 3.3 Configure Data Access Control Lists: Configure data access control lists based on a user's need to know. Apply data access control lists, also known as access permissions, to local and remote file systems, databases, and applications. (IG 1, IG 2, IG 3)
v7 - 14.6 Protect Information through Access Control Lists: Protect all information stored on systems with file system, network share, claims, application, or database specific access control lists. These controls will enforce the principle that only authorized individuals should have access to the information based on their need to access the information as a part of their responsibilities. (IG 1, IG 2, IG 3)
MITRE ATT&CK Mappings: T1548, T1548.000 - Tactics: TA0005 - Mitigations: M1026