The SSH client must be configured to not use CBC-based ciphers.

From SOLARIS 10 SPARC SECURITY TECHNICAL IMPLEMENTATION GUIDE

Associated with IA controls: ECSC-1

Associated with: CCI-000366

SV-26755r1_rule The SSH client must be configured to not use CBC-based 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 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 /etc/ssh/ssh_config and add or edit the "Ciphers" line. Only include ciphers that start with "3des" or "aes" and do not contain "cbc". For the list of available ciphers for the particular version of your software, consult the ssh_config manpage.

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