The ESXi host Secure Shell (SSH) daemon must not allow compression or must only allow compression after successful authentication.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-256390 | ESXI-70-000021 | SV-256390r959010_rule | CCI-000366 | 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 7.0 ESXi Security Technical Implementation Guide | 2025-02-11 | |||
Details
Check Text (C-256390r959010_chk)
From an ESXi shell, run the following command:
# /usr/lib/vmware/openssh/bin/sshd -T|grep compression
Expected result:
compression no
If the output does not match the expected result, this is a finding.
Fix Text (F-60008r885950_fix)
From an ESXi shell, add or correct the following line in "/etc/ssh/sshd_config":
Compression no