The parsing engine in IBM ISS Proventia can be bypassed by manipulating RAR archives in a certain way that the IBM engine cannot extract the content but the end user is able to.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/76302/TZO-06-2009.txt
Source: https://packetstormsecurity.com/files/76302/IBM-ISS-Proventia-Evasion.html