Title

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

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.

Additional Identifiers

Rule ID: SV-46017r1_rule

Vulnerability ID: V-22462

Group Title: GEN005511

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.