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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-207622	ESXI-65-000021	SV-207622r388482_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 vSphere 6.5 ESXi Security Technical Implementation Guide	2021-09-22

Details

Check Text ( C-7877r364265_chk )
From an SSH session connected to the ESXi host, or from the ESXi shell, run the following command: # grep -i "^Compression" /etc/ssh/sshd_config If there is no output or the output is not exactly "Compression no", this is a finding.

Fix Text (F-7877r364266_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": Compression no