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

From SUSE Linux Enterprise Server v11 for System z

Associated with: CCI-000366

SV-46010r2_rule The SSH daemon must be configured to not use Cipher-Block Chaining (CBC) ciphers.

Vulnerability discussion

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

Check content

Check the SSH daemon configuration for allowed ciphers. # grep -i ciphers /etc/ssh/sshd_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 daemon configuration and remove any ciphers ending with "cbc". If necessary, add a "Ciphers" line. Restart the SSH daemon. # /sbin/service sshd restart

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