Title

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

Discussion

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

Check Content

Open a terminal session and enter the following command. grep -i ciphers /etc/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

Open a terminal session and edit the SSH client configuration file "/etc/ssh_config" and remove any ciphers ending with "CBC".

Additional Identifiers

Rule ID: SV-39374r1_rule

Vulnerability ID: V-22462

Group Title:

Expert Comments

CCIs tied to check.

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