Eliminating XSS by adopting Trusted Types

About this presentation

Year after year, Cross-Site Scripting (XSS) continues to be the most expensive type of web vulnerability found in bug bounty programs. The most common variant of XSS occurs on the client side, when untrusted user input is passed to dangerous DOM APIs. Trusted Types is a novel web browser API designed to eliminate DOM-based XSS. It locks down dangerous DOM sinks, asking developers to prove that input is safe by using an appropriate security policy to avoid triggering a Trusted Types violation. Analyzing results from Google's Vulnerability Reward Program, it has been shown to prevent at least 61% of DOM-based XSS that Google's static code analysis pipeline missed. In this talk we show how web applications can significantly strengthen their security posture against DOM-based XSS by adopting Trusted Types, as well as the steps required to identify, fix, and prevent future Trusted Types violations.