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-22488	GEN005539	SV-46107r2_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
SUSE Linux Enterprise Server v11 for System z Security Technical Implementation Guide	2018-09-19

Details

Check Text ( C-43364r1_chk )
Check the SSH daemon configuration for the compression setting. # grep -i Compression /etc/ssh/sshd_config | egrep "no|delayed" If the setting is missing or is commented out, this is a finding. If the setting is present but is not set to "no" or "delayed", this is a finding.

Fix Text (F-39448r3_fix)
Edit the SSH daemon configuration and add or edit the "Compression" setting value to "no" or "delayed". Restart the SSH daemon. # /sbin/service sshd restart