Title

The Red Hat Enterprise Linux operating system must audit all uses of the fchownat syscall. (Cat II impact)

Discussion

Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one. Audit records can be generated from various components within the information system (e.g., module or policy filter). When a user logs on, the auid is set to the uid of the account that is being authenticated. Daemons are not user sessions and have the loginuid set to -1. The auid representation is an unsigned 32-bit integer, which equals 4294967295. The audit system interprets -1, 4294967295, and "unset" in the same way. Satisfies: SRG-OS-000064-GPOS-00033, SRG-OS-000392-GPOS-00172, SRG-OS-000458-GPOS-00203, SRG-OS-000474-GPOS-00219

Check Content

Verify the operating system generates audit records when successful/unsuccessful attempts to use the "fchownat" syscall occur. Check the file system rules in "/etc/audit/audit.rules" with the following commands: # grep -iw fchownat /etc/audit/audit.rules -a always,exit -F arch=b32 -S fchownat -F auid>=1000 -F auid!=unset -k perm_mod -a always,exit -F arch=b64 -S fchownat -F auid>=1000 -F auid!=unset -k perm_mod If both the "b32" and "b64" audit rules are not defined for the "fchownat" syscall, this is a finding.

Fix Text

Add or update the following rules in "/etc/audit/rules.d/audit.rules": -a always,exit -F arch=b32 -S fchownat -F auid>=1000 -F auid!=unset -k perm_mod -a always,exit -F arch=b64 -S fchownat -F auid>=1000 -F auid!=unset -k perm_mod The audit daemon must be restarted for the changes to take effect.

Additional Identifiers

Rule ID: SV-204520r603261_rule

Vulnerability ID: V-204520

Group Title: SRG-OS-000064-GPOS-00033

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.