The SSH daemon must not allow compression or must only allow compression after successful authentication.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-39285	GEN005539-ESXI5-000113	SV-51101r2_rule		Medium

Description
If compression is allowed in an SSH connection prior to authentication, vulnerabilities in the compression software could result in compromise of the system from an unauthenticated connection, potentially with root privileges.

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

Details

Check Text ( C-46549r2_chk )
Disable lock down mode. Enable the ESXi Shell. Execute the following command(s): # grep Compression /etc/ssh/sshd_config If the command returns nothing, or if the "Compression" attribute is set to "yes", this is a finding. Re-enable lock down mode.

Fix Text (F-44264r2_fix)
Disable lock down mode. Enable the ESXi Shell. Execute the following command(s): # vi /etc/ssh/sshd_config Add/modify the attribute line entry to the following (quotes for emphasis only): "Compression no" or "Compression delayed" Re-enable lock down mode.