← Back to SUSE Linux Enterprise Server v11 for System z Security Technical Implementation Guide

V-22462

CAT II (Medium)

The SSH client must be configured to not use Cipher-Block Chaining (CBC)-based ciphers.

Rule ID

SV-46017r1_rule

STIG

SUSE Linux Enterprise Server v11 for System z Security Technical Implementation Guide

Version

V1R12

CCIs

CCI-000366

Discussion

The (CBC) mode of encryption as implemented in the SSHv2 protocol is vulnerable to chosen-plaintext attacks and must not be used.

Check Content

Check the SSH client configuration for allowed ciphers.
# grep -i ciphers /etc/ssh/ssh_config | grep -v '^#' 
If no lines are returned, or the returned ciphers list contains any cipher ending with "cbc", this is a finding.

Fix Text

Edit the SSH client configuration and remove any ciphers ending with "cbc". If necessary, add a "Ciphers" line.