Скачать или смотреть XSS Lab 27 || Reflected XSS with event handlers and href attributes blocked || PortSwigger Labs

In this professional walkthrough we solve PortSwigger XSS Lab 27: Reflected XSS with event handlers and href attributes blocked. This video demonstrates, in a safe PortSwigger lab environment, how XSS can still be possible even when common sinks like inline event handlers and href attributes are blocked — and how to reason about remaining attack surfaces and mitigations.

What you’ll learn (lab-only, defensive):

Why blocking inline on* event handlers and href attributes reduces risk but may not eliminate all XSS vectors.

How to analyze the HTML/JS context to find residual sinks (e.g., CSS/URL contexts, data attributes, DOM APIs, SVG, attribute parsing quirks).

Safe, step-by-step lab methodology to identify source→sink flows and verify impact in an authorized test environment.

Practical defensive measures: avoid reflecting untrusted input, apply strict context-aware encoding/escaping, remove inline handlers and use safe event binding patterns, enforce a strong Content Security Policy (use nonces/hashes), set HttpOnly/SameSite/Secure for cookies, sanitize inputs with a vetted library, and add runtime monitoring/WAF rules.

Incident response basics: contain, rotate tokens/sessions if needed, patch the root cause, and document remediation.

Legal & Ethical: All demonstrations are strictly for education and defense in authorized labs. Do not test these techniques on systems you do not own or have explicit permission to test.

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