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Ensure auditd Collects Unauthorized Access Attempts to Files (unsuccessful)

An XCCDF Rule

Description

At a minimum the audit system should collect unauthorized file accesses for all users and root. If the auditd daemon is configured to use the augenrules program to read audit rules during daemon startup (the default), add the following lines to a file with suffix .rules in the directory /etc/audit/rules.d: 

-a always,exit -F arch=b32 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access
-a always,exit -F arch=b32 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access
If the system is 64 bit then also add the following lines: 
-a always,exit -F arch=b64 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access
-a always,exit -F arch=b64 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access
If the auditd daemon is configured to use the auditctl utility to read audit rules during daemon startup, add the following lines to /etc/audit/audit.rules file: 
-a always,exit -F arch=b32 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access
-a always,exit -F arch=b32 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access
If the system is 64 bit then also add the following lines: 
-a always,exit -F arch=b64 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EACCES -F auid>=1000 -F auid!=unset -F key=access
-a always,exit -F arch=b64 -S creat,open,openat,open_by_handle_at,truncate,ftruncate -F exit=-EPERM -F auid>=1000 -F auid!=unset -F key=access

warning alert: Warning

This rule checks for multiple syscalls related to unsuccessful file modification; it was written with DISA STIG in mind. Other policies should use a separate rule for each syscall that needs to be checked. For example:
  • audit_rules_unsuccessful_file_modification_open
  • audit_rules_unsuccessful_file_modification_ftruncate
  • audit_rules_unsuccessful_file_modification_creat

Rationale

Unsuccessful attempts to access files could be an indicator of malicious activity on a system. Auditing these events could serve as evidence of potential system compromise.

ID
xccdf_org.ssgproject.content_rule_audit_rules_unsuccessful_file_modification
Severity
Medium
References
Updated