filter-js-from-html

Bypassing HTML sanitizers to execute JavaScript involves systematically analyzing parser differences, alternative event handlers, and URL schemes to craft payloads that evade filters like DOMPurify or BeautifulSoup. This skill provides a categorized methodology for identifying and exploiting these filtering weaknesses.

Analyzing custom HTML filter implementations for CTF challenges requires identifying the specific parsing libraries and filtering rules in use. This skill delivers a structured workflow to map filter behavior, categorize potential bypass techniques, and validate payload preservation through a testing harness.

Yes, this HTML sanitizer bypass methodology works with DOMPurify and BeautifulSoup by exploiting parser differences and alternative execution vectors. It is specifically designed for security testing, CTF challenges, and penetration testing scenarios involving these common sanitization filters.

Your XSS payload gets stripped by the HTML sanitizer because the filter identifies and removes malicious scripts, event handlers, or dangerous URL schemes. This skill helps you analyze the specific filtering rules and craft alternative vectors that preserve payload syntax while achieving code execution.

Yes, you can validate browser execution of bypass payloads without external libraries by using a Python testing harness. This skill provides guidance on building scripts to verify both payload preservation through the sanitizer and subsequent JavaScript execution in the browser environment.

Alternative vectors to bypass JavaScript sanitization filters include exploiting parser differences, utilizing alternative event handlers, manipulating URL schemes, and executing CSS attacks. This skill categorizes these techniques to help you systematically test and circumvent various HTML and JavaScript filtering mechanisms.