cyberstrikeus 4.1.14 Ensure file deletion events by users are collected (Scored)
Profile Applicability
- Level 2 - Server
- Level 2 - Workstation
Description
Monitor the use of system calls associated with the deletion or renaming of files and file attributes. This configuration statement sets up monitoring for the unlink (remove a file), unlinkat (remove a file attribute), rename (rename a file) and renameat (rename a file attribute) system calls and tags them with the identifier "delete".
Rationale
Monitoring these calls from non-privileged users could provide a system administrator with evidence that inappropriate removal of files and file attributes associated with protected files is occurring. While this audit option will look at all events, system administrators will want to look for specific privileged files that are being deleted or altered.
Audit Procedure
On a 32 bit system run the following commands:
grep delete /etc/audit/audit.rules
auditctl -l | grep delete
Verify output of both matches:
-a always,exit -F arch=b32 -S unlink -S unlinkat -S rename -S renameat -F auid>=1000 -F auid!=4294967295 -k delete
On a 64 bit system run the following commands:
grep delete /etc/audit/audit.rules
auditctl -l | grep delete
Verify output of both matches:
-a always,exit -F arch=b64 -S unlink -S unlinkat -S rename -S renameat -F auid>=1000 -F auid!=4294967295 -k delete
-a always,exit -F arch=b32 -S unlink -S unlinkat -S rename -S renameat -F auid>=1000 -F auid!=4294967295 -k delete
Expected Result
The audit rules for delete should be present and active.
Remediation
For 32 bit systems add the following lines to the /etc/audit/audit.rules file:
-a always,exit -F arch=b32 -S unlink -S unlinkat -S rename -S renameat -F auid>=1000 -F auid!=4294967295 -k delete
For 64 bit systems add the following lines to the /etc/audit/audit.rules file:
-a always,exit -F arch=b64 -S unlink -S unlinkat -S rename -S renameat -F auid>=1000 -F auid!=4294967295 -k delete
-a always,exit -F arch=b32 -S unlink -S unlinkat -S rename -S renameat -F auid>=1000 -F auid!=4294967295 -k delete
Notes: At a minimum, configure the audit system to collect file deletion events for all users and root.
Reloading the auditd config to set active settings may require a system reboot.
Default Value
Not configured by default.
References
- CIS Controls v6.1 - 3.6 Implement Automated Configuration Monitoring System
Profile
- Level 2 - Server
- Level 2 - Workstation