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


Overview

Finding ID Version Rule ID IA Controls Severity
V-22462 GEN005511 SV-26755r1_rule ECSC-1 Medium
Description
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.
STIG Date
UNIX SRG 2013-03-26

Details

Check Text ( C-27764r1_chk )
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 (F-24004r1_fix)
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.