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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-239278	ESXI-67-000023	SV-239278r674763_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 6.7 ESXi Security Technical Implementation Guide	2022-01-05

Details

Check Text ( C-42511r674761_chk )
From an SSH session connected to the ESXi host, or from the ESXi shell, 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-42470r674762_fix)
From an SSH session connected to the ESXi host, or from the ESXi shell, add or correct the following line in "/etc/ssh/sshd_config": X11Forwarding no