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V-282747

CAT II (Medium)

TOSS 5 must be configured so the rsyslog daemon does not accept log messages from other servers unless the server is being used for log aggregation.

Rule ID

SV-282747r1201386_rule

STIG

Tri-Lab Operating System Stack (TOSS) 5 Security Technical Implementation Guide

Version

V1R1

CCIs

CCI-000366

Discussion

Unintentionally running an rsyslog server that accepts 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).

Check Content

Verify TOSS 5 is not configured to receive remote logs using rsyslog with the following commands:

$ grep -i modload /etc/rsyslog.conf /etc/rsyslog.d/*
$ModLoad imtcp
$ModLoad imrelp

$ grep -i serverrun /etc/rsyslog.conf /etc/rsyslog.d/*
$InputTCPServerRun 514
$InputRELPServerRun 514

Note: An error about no files or directories may be returned. This is not a finding.

If any lines are returned by the command, then rsyslog is configured to receive remote messages, and this is a finding.

Fix Text

Configure TOSS 5 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:

$ModLoad imtcp
$ModLoad imudp
$ModLoad imrelp
$InputTCPServerRun [0-9]*
$UDPServerRun [0-9]*
$InputRELPServerRun [0-9]*

Restart the rsyslog daemon for the changes to take effect.

$ sudo systemctl restart rsyslog.service