RHEL 9 must be configured so that the rsyslog daemon does not accept log messages from other servers unless the server is being used for log aggregation.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-258143	SRG-OS-000480-GPOS-00227	RHEL-09-652025	SV-258143r1155671_rule	2025-11-24	2

Description
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).

Description

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).

ℹ️ Check
Note: If the system administrator can demonstrate that another tool (e.g., SPLUNK) is being used to manage log off-load and aggregation in lieu of rsyslog, this check is not applicable. Verify RHEL 9 is not configured to receive remote logs using rsyslog with the following commands: $ 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.

ℹ️ Check

Note: If the system administrator can demonstrate that another tool (e.g., SPLUNK) is being used to manage log off-load and aggregation in lieu of rsyslog, this check is not applicable. Verify RHEL 9 is not configured to receive remote logs using rsyslog with the following commands: $ 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.

✔️ Fix
Configure RHEL 9 to not receive remote logs using rsyslog. Remove the lines in /etc/rsyslog.conf and any files in the /etc/rsyslog.d directory that match any of the following: InputTCPServerRun UDPServerRun RELPServerRun module(load="imtcp") module(load="imudp") module(load="imrelp") input(type="imudp" port="514") input(type="imtcp" port="514") input(type="imrelp" port="514") The rsyslog daemon must be restarted for the changes to take effect: $ sudo systemctl restart rsyslog.service

✔️ Fix

Configure RHEL 9 to not receive remote logs using rsyslog. Remove the lines in /etc/rsyslog.conf and any files in the /etc/rsyslog.d directory that match any of the following: InputTCPServerRun UDPServerRun RELPServerRun module(load="imtcp") module(load="imudp") module(load="imrelp") input(type="imudp" port="514") input(type="imtcp" port="514") input(type="imrelp" port="514") The rsyslog daemon must be restarted for the changes to take effect: $ sudo systemctl restart rsyslog.service