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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-63215	ESXI-06-000023	SV-77705r1_rule		Medium

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.

STIG	Date
VMware vSphere ESXi 6.0 Security Technical Implementation Guide	2019-01-04

Details

Check Text ( C-63949r1_chk )
To verify the X11Forwarding setting, run the following command: # grep -i "^X11Forwarding" /etc/ssh/sshd_config If there is no output or the output is not exactly "X11Forwarding no", this is a finding.

Fix Text (F-69133r1_fix)
To set the X11Forwarding setting, add or correct the following line in "/etc/ssh/sshd_config": X11Forwarding no