XSS-Guard: Precise Dynamic Detection of Cross-Site Scripting Attacks

This paper focuses on defense mechanisms for cross-site scripting at- tacks, the top threat on web applications today. It is believed that input validation (or filtering) can effectively prevent XSS attacks on the server side. In this pa- per, we discuss several recent real-world XSS attacks and analyze the reasons for the failure of filtering mechanisms in defending these attacks. We conclude that while filtering is useful as a first level of defense against XSS attacks, it is ineffective in preventing several instances of attack, especially when user input includes content-rich HTML. We then propose XSS-GUARD, a new framework that is designed to be a prevention mechanism against XSS attacks on the server side. XSS-GUARD works by dynamically learning the set of scripts that a web application intends to create for any HTML request. Our approach also includes a robust mechanism for identifying scripts at the server side and removes any script in the output that is not intended by the web application. We discuss extensive ex- perimental results that demonstrate the resilience of XSS-GUARD in preventing a number of real-world XSS exploits.

 @inproceedings{
  DIMVA08:Injection,
  author        = {Prithvi Bisht and V. N. Venkatakrishnan},
  crossref      = {DIMVA08},
  title         = {{XSS-GUARD}: Precise Dynamic Detection of Cross-Site Scripting Attacks}
}
@proceedings{
  DIMVA08,
  booktitle     = {5th GI International Conference on Detection of Intrusions \&
  Malware, and Vulnerability Assesment},
  location      = {Paris, France},
  month         = Jul,
  year          = {2008}
}