The SSH daemon must be configured to not allow X11 forwarding.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-22468	GEN005519	SV-26761r1_rule	ECSC-1	Low

Description
X11 forwarding over SSH allows for the secure remote execution of X11-based applications. This feature can increase the attack surface of an SSH connection and should not be enabled unless needed. If this function is necessary to support a valid mission requirement, its use must be authorized and approved in the system accreditation package.

STIG	Date
UNIX SRG	2013-03-26

Details

Check Text ( C-27770r1_chk )
Check the SSH daemon configuration for the X11 forwarding setting. # grep -i X11Forwarding /etc/ssh/sshd_config | grep -v '^#' If no lines are returned, or the returned setting has a value evaluating to yes, this is a finding.

Fix Text (F-24011r1_fix)
Edit the SSH daemon configuration and change or add the X11Forwarding setting to no.