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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
GEN005519-ESXI5-000102	GEN005519-ESXI5-000102	GEN005519-ESXI5-000102_rule		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.

STIG	Date
VMware ESXi v5 Security Technical Implementation Guide	2013-01-15

Details

Check Text ( C-GEN005519-ESXI5-000102_chk )
Disable lock down mode. Enable the ESXi Shell. Check the SSH daemon configuration for the X11 forwarding setting. # grep -i "^X11Forwarding" /etc/ssh/sshd_config If "X11Forwarding" is set to "yes", this is a finding. Re-enable lock down mode.

Fix Text (F-GEN005519-ESXI5-000102_fix)
Disable lock down mode. Enable the ESXi Shell. Edit the SSH daemon configuration and add/modify the "X11Forwarding" configuration, setting it to "no". # vi /etc/ssh/sshd_config Re-enable lock down mode.