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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-22462	GEN005511 M6	SV-39374r1_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-38319r1_chk )
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 (F-33608r1_fix)
Open a terminal session and edit the SSH client configuration file "/etc/ssh_config" and remove any ciphers ending with "CBC".