The information in this document is based on a Cisco ASA 5506 with OS 9.6.1. Adaptive Security Appliance ASA platform architecture.Prerequisites RequirementsĬisco recommends that you have knowledge of these topics: On scan vulnerability CVE-2008-5161 it is documented that the use of a block cipher algorithm in Cipher Block Chaining (CBC) mode, makes it easier for remote attackers to recover certain plain text data from an arbitrary block of cipher text in an SSH session via unknown vectors.Ĭipher Block Chaining (CBC) is a mode of operation for cipher block, this algorithm uses a block cipher to provide an informational service such as confidentiality or authenticity. This document describes how to disable SSH server CBC mode Ciphers on ASA.