Cross-Site Scripting (XSS) allows attackers to inject malicious scripts into web pages viewed by other users.

Cross-Site Scripting (XSS) Simulator

Inject malicious scripts to steal sessions and hijack accounts

Simple script tag injection to execute JavaScript

Vulnerable application

Victim Browser

https://vulnerable-site.com/search?q=...

Waiting for XSS injection...

Injected Payload
<script>alert(document.cookie)</script>

Attack Console

Ready
Inject Payload
Execute Script
Steal Session
Hijacked
Waiting to start...

Defense Mechanisms & Bypass Techniques

Defense Techniques:

  • • Input Validation: Whitelist allowed characters
  • • Output Encoding: HTML encode user input
  • • CSP Headers: Restrict script sources
  • • Content Sanitization: Remove dangerous tags

Bypass Techniques:

  • • Obfuscation: Encode payloads to evade filters
  • • CSP Bypass: Use trusted CDNs or nonce reuse
  • • Alternative Vectors: Event handlers, data URIs
  • • DOM Manipulation: Client-side only attacks

OPSEC: Training Environment Only

XSS attacks are illegal without authorization. This simulation is for educational purposes. Always use input validation, output encoding, and CSP headers. OWASP Top 10 #3 vulnerability.