Testing for DOM XSS using web messages - Port Swigger
Summary: PortSwigger's DOM Invader tool now logs, modifies, and automatically resends web messages sent via postMessage() to help testers probe for DOM XSS, with the features disabled by default until Postmessage interception is switched on and the browser reloaded. By default it injects a canary into the message's data property and replaces the message origin with a fake origin that starts and ends with the expected domain name, then flags messages with an estimated severity and confidence level.
Why it matters: The tool's default fake origin is built to break event handlers that validate origin with flawed logic or regular expressions, and messages whose client-side code never reads the origin property are flagged as likely unvalidated - a gap an attacker can reach from any external domain.
Read the original at PortSwigger Research ↗
- Topics
- Vulnerabilities & Patching
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