Syntax-Tree Depth Bounding and Frame Authorization for GraphQL, gRPC, and WebSocket Interfaces
An attacker uses a single GraphQL request to extract the entire internal database schema, packs a thousand password guesses into one batched query, or hijacks a persistent WebSocket stream. The verifier parses query syntax trees safely and compiles depth, alias, and origin bounds for border enforcement.
Multiplexed and streaming protocols such as GraphQL, gRPC, and WebSocket bypass traditional path-based access controls by routing all operations through a single endpoint or persistent binary channel. Common exposures include unauthenticated schema introspection or server reflection, brute-force credential stuffing via alias batching, field-level authorization bypass in nested resolvers, and cross-site WebSocket connection hijacking.
Security Officer (Plain Meaning): Halts "Execute recursive circular GraphQL fragment bomb (depth > 32) or cross-site WebSocket hijacking without Origin lock" before socket (0 live DB damage, signed GOST receipt)
IT Auditor & SecOps (Evidence): Scope OWASP API4:2023 / API8:2023 | Wire Rule SEC-ZD-V2-04 | Formal Witness b208d461a95c3e78
Technocrat, CTO & VC (Moat): Z3 Invariant (assert (and (<= (gql_ast_depth query) 6) (<= (gql_alias_c... | FP = 0.0% | Contract IMMUNE-GQL-B208D461 (mcp-sentinel 1.1.2)1. In-Path Interception and Contract Synthesis Schematic for API-GQL-04
Deterministic verification flow for API-GQL-04 (OWASP API4:2023 / API8:2023, WSTG-APIT-02 / CWE-400): wire filter SEC-ZD-V2-04 intercepts destructive mutations prior to socket delivery, formal witness b208d461a95c3e78 proves the flaw, and compiler emits gateway rule IMMUNE-GQL-B208D461 for mcp-sentinel.
2. Zero-Damage Wire Filtering and Formal Solver Invariant for API-GQL-04
Under rule SEC-ZD-V2-04, the in-path software filter parses candidate graph queries into an abstract syntax tree (AST) prior to transmission. Recursive fragment bombs, cyclic nesting chains, and unauthenticated stream mutations are blocked before reaching the target socket.
On the benchmark stand, the verifier evaluates bounded introspection probes, dual-alias batching checks, and upgrade-header handshakes against vulnerable and hardened handlers. The differential comparison produces formal witness b208d461a95c3e78 with zero false alarms.
Class Identifier: API-GQL-04 (graphql_grpc_websocket)
Taxonomy Concordance: OWASP API4:2023 / API8:2023 | WSTG-APIT-02 / CWE-400
Execution Mode: Active Safe Probing (AUTO_SCAN)
Candidate Probe: POST /graphql {"query":"query { __schema { types { name fields { name } } } a1:login(p:\"1\") a2:login(p:\"2\") }"}
Blocked Mutation: Execute recursive circular GraphQL fragment bomb (depth > 32) or cross-site WebSocket hijacking without Origin lock
Z3 Solver Invariant: (assert (and (<= (gql_ast_depth query) 6) (<= (gql_alias_count query) 4) (= (prod_introspection query) false) (= (ws_origin_verified upgrade) true)))
Wire Sandbox Rule: SEC-ZD-V2-04
Formal Witness Hash: b208d461a95c3e78
Compiled Sentinel Rule: IMMUNE-GQL-B208D461 (mcp-sentinel 1.1.2)3. Autonomous Synthesis of Gateway Contract IMMUNE-GQL-B208D461 and Streebog-256 Receipt
From witness b208d461a95c3e78, the compiler generates rule IMMUNE-GQL-B208D461 for border enforcement. The contract disables production schema introspection and reflection, caps query depth and alias count, and validates Origin and per-frame authorization tokens inside mcp-sentinel.
4. Engineering Reference Notes for API-GQL-04
Stopping brute-force attacks hidden inside a single GraphQL HTTP request
Because attackers can pack hundreds of aliased mutation calls into a single HTTP POST body, the gateway counts individual operation aliases inside the parsed syntax tree and enforces rate limits per resolved field rather than per network packet.
Securing persistent WebSocket and gRPC streams after the initial handshake
The compiled contract validates origin headers during connection upgrade and re-evaluates session scope and message schema on every individual frame transmitted over the stream.