DOM-Based XSS Detection Techniques

DOM-Based XSS Detection Techniques

DOM XSS requires analyzing client-side JavaScript rather than server responses. Use ZAP's proxy to capture JavaScript files, then analyze them for dangerous patterns. Look for sources of user input like location.href, document.URL, or window.name. Trace how this input flows to dangerous sinks like innerHTML, eval(), or document.write().

The Ajax Spider aids DOM XSS detection by executing JavaScript and observing behavior. Configure the Ajax Spider with appropriate browser settings and let it explore the application. Monitor the ZAP alerts for DOM-based XSS findings. However, Ajax Spider might miss complex scenarios requiring specific interaction sequences or timing.

Manual JavaScript analysis often reveals DOM XSS that tools miss. Modern frameworks use complex data binding and templating that complicate analysis. Use browser developer tools to set breakpoints in JavaScript code, tracing user input flow. Test suspicious code paths by manipulating URL parameters, hash fragments, or other client-side input sources while observing JavaScript execution.