V-258143

Discussion

Unintentionally running a rsyslog server accepting remote messages puts the system at increased risk. Malicious rsyslog messages sent to the server could exploit vulnerabilities in the server software itself, could introduce misleading information into the system's logs, or could fill the system's storage leading to a denial of service. If the system is intended to be a log aggregation server, its use must be documented with the information system security officer (ISSO).

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Note: If the system administrator (SA) can demonstrate that another tool (e.g., SPLUNK) is being used to manage log off-load and aggregation in lieu of rsyslog, this is not applicable.

Verify RHEL 9 is not configured to receive remote logs using rsyslog with the following command:

$ ss -tulnp | grep rsyslog

If no output is returned, rsyslog is not listening for remote messages and is compliant.

If output appears, check for configured ports (514 is the default for syslog).

Check for remote logging configuration in rsyslog by examining the rsyslog configuration files:

$ sudo grep -E 'InputTCPServerRun|UDPServerRun|RELPServerRun|imtcp|imudp|imrelp' /etc/rsyslog.conf /etc/rsyslog.d/*

If this command returns uncommented lines enabling network listeners, the system is accepting remote logs.  If this system is not documented and authorized as a log aggregation server, this is a finding.