Abstract

Web 2.0 applications are using dynamic DOM manipulations extensively for presenting JSON or XML streams in the browser. These DOM calls mixed with XMLHttpRequest (XHR) object are part of client side logic written in JavaScript or part of any other client side technology be it Flash or Silverlight. DOM driven XSS is a sleeping giant in the application code and it can be exploited by an attacker to gain access to the end user’s browser/desktop. This can become a root cause of following set of interesting vulnerabilities – Cross Widget Sniffing, RSS feed reader exploitation, XHR response stealing, Mashup hacking, Malicious code injection, Spreading Worm etc. This set of vulnerability needs innovative way of scanning the application and corresponding methodology needs to be tweaked. We have seen DOM driven XSS exploited in various different popular portals to spread worm or virus. This is a significant threat on the rise and should be mitigated by validating un-trusted content poisoning Ajax or Flash routines. DOM driven XSS, Cross Domain Bypass and CSRF can cause a deadly cocktail to exploit Web 2.0 applications across Internet. This presentation will be covering following important issues and concepts.

• Web 2.0 Architecture and DOM manipulation points
• JavaScript exploits by leveraging DOM
• Cross Domain Bypass and Hacks
• DOM hacking for controlling Widgets and Mashups
• Exploiting Ajax routines to gain feed readers
• Scanning and detecting DOM driven XSS in Web 2.0
• Tools for scanning the DOM calls
• Mitigation strategies for better security posture