CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - 6.1.6
Profile Applicability
- Level 1 - Server
- Level 1 - Workstation
Description
The /etc/shadow file is used to store the information about user accounts 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/shadow 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/shadow file (such as expiration) could also be useful to subvert the user accounts.
Audit Procedure
Command Line
Run the following command and verify Uid is 0/root, Gid is 0/root or <gid>/shadow, and Access is 640 or more restrictive:
stat /etc/shadow
Expected Result
Access: (0640/-rw-r-----) Uid: ( 0/ root) Gid: ( 0/ root)
Remediation
Command Line
Run one of the following commands to set ownership of /etc/shadow to root and group to either root or shadow:
chown root:root /etc/shadow
chown root:shadow /etc/shadow
Run the following command to remove excess permissions from /etc/shadow:
chmod u-x,g-wx,o-rwx /etc/shadow
Default Value
Access: (0640/-rw-r-----) Uid: ( 0/ root) Gid: ( 0/ root)
References
- CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0
CIS Controls
| Controls Version | Control |
|---|
| v7 | 16.4 Encrypt or Hash all Authentication Credentials Encrypt or hash with a salt all authentication credentials when stored. |
Assessment Status
Automated