cyberstrikeus 7.1.9 Ensure access to /etc/shells is configured (Automated)
Profile
- Level 1 - Server
- Level 1 - Workstation
Description
/etc/shells is a text file which contains the full pathnames of valid login shells. This file is consulted by chsh and available to be queried by other programs.
Rationale
It is critical to ensure that the /etc/shells file is protected from unauthorized access. Although it is protected by default, the file permissions could be changed either inadvertently or through malicious actions.
Impact
None
Audit Procedure
Command Line
Run the following command to verify /etc/shells is mode 644 or more restrictive, Uid is 0/root and Gid is 0/root:
# stat -Lc 'Access: (%#a/%A) Uid: ( %u/ %U) Gid: ( %g/ %G)' /etc/shells
Expected Result
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
Remediation
Command Line
Run the following commands to remove excess permissions, set owner, and set group on /etc/shells:
# chmod u-x,go-wx /etc/shells
# chown root:root /etc/shells
Default Value
Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)
References
- NIST SP 800-53 Rev. 5: AC-3, MP-2
CIS Controls
| Controls Version | Control | IG 1 | IG 2 | IG 3 |
|---|---|---|---|---|
| v8 | 3.3 Configure Data Access Control Lists | X | X | X |
| v7 | 14.6 Protect Information through Access Control Lists | X | X | X |
MITRE ATT&CK Mappings:
| Techniques / Sub-techniques | Tactics | Mitigations |
|---|---|---|
| T1003, T1003.008, T1222, T1222.002 | TA0005 | M1022 |