In September 2004, much hype was made of a buffer overflow vulnerability that existed in the Microsoft engine responsible for processing JPEG files. While the resulting vulnerability itself was nothing new, the fact that a vulnerability could be caused by a non-executable file commonly traversing public and private networks was reason for concern. File format vulnerabilities are emerging as more and more frequent attack vector. These attacks take advantage of the fact that an exploit can be carried within non-executable files that were previously considered to be innocuous. As a result, firewalls and border routers rarely prevent the files from entering a network when included as email attachments or downloaded from the Internet.