Cross-Site Scripting Worms and Viruses: The Impending Threat and the Best Defense

On October 4, 2005, the “Samy Worm1” became the first major worm to use Cross-Site Scripting2 (“XSS”) for infection propagation. Overnight, the worm altered over one million personal user profiles on MySpace.com, the most popular social networking site in the world. The worm infected the site with JavaScript viral code and made Samy, the hacker, everyone’s pseudo “friend” and “hero.”3 MySpace, at the time home to over 32 million users and a top-10 trafficked website in the U.S. (Based on Alexa rating), was forced to shutdown in order to stop the onslaught.

Samy, the author of the worm, was on a mission to be famous, and as such the payload was relatively benign. But consider what he might have done with control of over one million Web browsers and the gigabits of bandwidth at their disposal–browsers that were also potentially logged-in to Google, Yahoo, Microsoft Passport, eBay, web banks, stock brokerages, blogs, message boards, or any other web-based applications. It’s critical that we begin to understand the magnitude of the risk associated with XSS malware and the ways that companies can defend themselves and their users. Especially when the malware originates from trusted websites and aggressive authors.

In this white paper we will provide an overview of XSS; define XSS worms; and examine propagation methods, infection rates, and potential impact. Most importantly, we will outline immediate steps enterprises can take to defend their websites.

Download the paper in PDF format here.