The document discusses the history and risks of malicious browser extensions. It begins with a brief history of malicious Firefox extensions from 2004-2012, noting a rise from 5 extensions in 2011 to 48 from January to October 2012. The document then demonstrates a home-made Firefox extension that can perform command and control, steal cookies/passwords, and execute code remotely. It discusses disadvantages of browser extensions compared to other malware. Finally, it acknowledges risks of zombie browsers and calls on antivirus developers, browser developers, website developers and users to address these risks.