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The SSH daemon must be configured to not use CBC ciphers.


Overview

Finding ID Version Rule ID IA Controls Severity
V-22459 GEN005506 M6 SV-39364r1_rule ECSC-1 Medium
Description
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.
STIG Date
MAC OSX 10.6 Workstation Security Technical Implementation Guide Draft 2013-01-10

Details

Check Text ( C-38312r1_chk )
Open a terminal session and enter the following command.

grep ciphers /etc/sshd_config

If no lines are returned, or the returned ciphers list contains any cipher ending with CBC, this is a finding.
Fix Text (F-33601r1_fix)
Open a terminal session and edit the SSH daemon configuration file "/etc/sshd_config" and remove any ciphers ending with "CBC". If necessary, add a Ciphers line.