Vulnerability Discussion

Information stored in one location is vulnerable to accidental or incidental deletion or alteration.

Offloading is a common process in information systems with limited audit storage capacity.

RHEL 9 installation media provides "rsyslogd", a system utility providing support for message logging. Support for both internet and Unix domain sockets enables this utility to support both local and remote logging. Coupling this utility with "gnutls" (a secure communications library implementing the SSL, TLS and DTLS protocols) creates a method to securely encrypt and offload auditing.

"Rsyslog" supported authentication modes include:
anon - anonymous authentication
x509/fingerprint - certificate fingerprint authentication
x509/certvalid - certificate validation only
x509/name - certificate validation and subject name authentication

Satisfies: SRG-OS-000342-GPOS-00133, SRG-OS-000479-GPOS-00224

Check

Verify RHEL 9 encrypts audit records offloaded onto a different system or media from the system being audited via rsyslog with the following command:

$ sudo grep -i '$ActionSendStreamDriverMode' /etc/rsyslog.conf /etc/rsyslog.d/*.conf

/etc/rsyslog.conf:$ActionSendStreamDriverMode 1

If the value of the "$ActionSendStreamDriverMode" option is not set to "1" or the line is commented out, this is a finding.

Fix

Configure RHEL 9 to encrypt offloaded audit records via rsyslog by setting the following options in "/etc/rsyslog.conf" or "/etc/rsyslog.d/[customfile].conf":

$ActionSendStreamDriverMode 1