Black Hat Briefings, Usa 2007 [audio] Presentations From The Security Conference.

The past year has seen several web worms attacks against various online applications. While these worms have gotten more sophisticated and made use of additional technologies like Flash and media formats, they all have some basic limitations such as infecting new domains and injection methods. These worms are fairly easily detected using signatures and these limitations have made web worms annoying, but ultimately controllable. Often the source website simply fixes a single flaw and the worm dies. In this presentation we will examine ways web worms might evolve to overcome these limitations. We describe a hybrid web worm combining both server-side and client side languages to exploit both the web server and the web browser to aid in its propagation across multiple hosts. We will discuss how such a hybrid worm is able to find new vulnerable systems and infect new hosts on different domains from both the client and the server. In addition will we look at how a hybrid worm could upgrade its infection methods