SKILL: GraphQL and Hidden Parameters — Introspection, Batching, and Undocumented Fields
AI LOAD INSTRUCTION: Use this skill when GraphQL exists or when REST documentation suggests optional, deprecated, or undocumented fields. Focus on schema discovery, hidden parameter abuse, and batching as a force multiplier.
1. GRAPHQL FIRST PASS
query { __typename }
query {
__schema {
types { name }
}
}If introspection is restricted, continue with:
- field suggestions and error-based discovery
- known type probes like
__type(name: "User") - JS and mobile bundle route extraction
2. HIGH-VALUE GRAPHQL TESTS
| Theme | Example |
|---|---|
| IDOR | user(id: "victim") |
| batching | array of login or object fetch operations |
| hidden fields | admin-only fields exposed in type definitions |
| nested authz gaps | related object fields with weaker checks |
3. HIDDEN PARAMETER DISCOVERY
Look for:
- fields present in admin docs but not public docs
additionalPropertiesor permissive schemas- frontend code using richer request bodies than visible UI controls
- mobile endpoints carrying role, org, feature-flag, or internal filter fields
4. NEXT ROUTING
- If hidden fields affect privilege: api authorization and bola
- If GraphQL batching changes auth or rate behavior: api auth and jwt abuse
- If endpoint discovery is incomplete: api recon and docs