This is a burp intruder extender that is designed for automation and validation of XSS vulnerabilities.

For more information, check out this blog post: http://blog.nvisium.com/2014/01/accurate-xss-detection-with-burpsuite.html

XSS Detection

The burp intruder extender will be designed to forward responses to the XSS detection server, that will need to be running externally.

The XSS detection server is powered by Phantom.js and/or Slimer.js.

The XSS detection is influenced by Trustwave's blog post: Server-Side XSS Attack Detection with ModSecurity and PhantomJS:http://blog.spiderlabs.com/2013/02/server-site-xss-attack-detection-with-modsecurity-and-phantomjs.html

Building Extender .Jar

To build the extender .jar file, we first need to ensure that the system has ant, and is running version Java 7 or higher.

First, download the apache HttpComponents Client libraries. These libraries are available for free from http://hc.apache.org/. Once the libraries have been downloaded, create a lib directory in the project root and move the .jar libraries into this directory:

$ mkdir /path/to/xssValidator/burp-extender/lib
$ mv /path/to/libs/*.jar /path/to/xssValidator/burp-extender/lib/

Now, navigate to the burp-extender/bin/burp directory:

$ cd burp-extender/bin/burp

Build the jar using Apache ant:

$ ant

After this has completed you should see a BUILD SUCCESSFUL message. The .jar file is located in burp-extender/bin/burp/xssValidator.jar. Import this into Burp.

Usage

Before starting an attack it is necessary to start the phantom and/or slimer xss-detection servers. Navigate to the xss-detector directory and execute the following to start phantom.js xss-detection script:

$ phantomjs xss.js &
$ slimerjs slimer.js &

The server is expecting base64 encoded page responses passed via the http-response, which will be passed via the Burp extender.

Examples

Within the xss-detector directory there is a folder of examples which can be used to test the extenders functionality.

• Basic-xss.php: This is the most basic example of a web application that is vulnerable to XSS. It demonstrates how legitimate javascript functionality, such as alerts and console logs, do not trigger false-positives.
• Bypass-regex.php: This demonstrates a XSS vulnerability that occurs when users attempt to filter input by running it through a single-pass regex.
• Dom-xss.php: A basic script that demonstrates the tools ability to inject payloads into javascript functionality, and detect their success.