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
• additionalProperties or 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