The SSH client must be configured to only use the SSHv2 protocol.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-39414	GEN005501-ESXI5-9778	SV-51272r2_rule		Medium

Description
SSHv1 is not a DoD-approved protocol and has many well-known vulnerability exploits. Exploits of the SSH client could provide access to the system with the privileges of the user running the client.

STIG	Date
VMware ESXi Server 5.0 Security Technical Implementation Guide	2017-01-06

Details

Check Text ( C-46688r3_chk )
Disable lock down mode. Enable the ESXi Shell. Check the SSH client configuration for required protocol. # grep -i "Protocol 2" /etc/ssh/ssh_config \| grep -v '^#' Re-enable lock down mode. If the returned protocol list contains anything except 2, this is a finding. If the /etc/ssh/ssh_config file does not exist or the Protocol option is not set, this is not a finding because the SSH client cannot enforce the Protocol setting on a compliant SSH server.

Check Text ( C-46688r3_chk )

Disable lock down mode.
Enable the ESXi Shell.

Check the SSH client configuration for required protocol. # grep -i "Protocol 2" /etc/ssh/ssh_config | grep -v '^#'

Re-enable lock down mode.

If the returned protocol list contains anything except 2, this is a finding. If the /etc/ssh/ssh_config file does not exist or the Protocol option is not set, this is not a finding because the SSH client cannot enforce the Protocol setting on a compliant SSH server.

Fix Text (F-44427r1_fix)
Disable lock down mode. Enable the ESXi Shell. Edit the SSH client configuration and add/modify the "Protocol" configuration for Protocol 2 only. # vi /etc/ssh/ssh_config Re-enable lock down mode.