API GRAPHQL

GraphQL abuse

When it applies

The target exposes a GraphQL endpoint. GraphQL collapses many objects behind one URL, so authorization gaps and info leaks are common and easy to miss with URL-based testing.

Why it works

One endpoint, a self-describing schema, and per-field resolvers mean access control must be enforced at every field/resolver — it frequently isn't. Introspection hands you the entire attack surface; batching/aliases turn one request into thousands.

Method

1. Fingerprint & map: graphw00f for the engine; if introspection is on, dump the schema ({__schema{types{name fields{name}}}}) with inql/clairvoyance. If off, brute field names with clairvoyance (error messages leak valid fields).
2. AuthZ testing (BOLA/BFLA): call queries/mutations for objects and admin operations you shouldn't reach; swap ids in arguments (same as IDOR) — resolvers often skip owner checks.
3. Info disclosure: reach sensitive fields/types (users, tokens, internal flags) via nested relations even when the "front door" query hides them.
4. DoS / cost: deeply nested recursive queries and aliased batching (a:login b:login ...) to bypass rate limits or brute-force — respect program rules on this.
5. Injection: arguments feed backends — test SQLi/NoSQLi in GraphQL variable values.

Gotchas

• Introspection off ≠ safe — field brute-forcing and suggestion errors still map the schema.
• Rate-limit bypass via batching/aliases is a real, reportable finding on many programs.
• Mutations are where impact lives; don't stop at read queries.

Verify success

Retrieve/modify data through a query or mutation your role shouldn't allow, or dump a schema that reveals hidden admin operations.

References

PortSwigger GraphQL labs; OWASP API Security Top 10 (2023); graphw00f/inql docs.