Sc GRAPHQL

SC: GraphQL Security

Purpose

Detects GraphQL-specific security vulnerabilities including query injection, introspection information disclosure, batching abuse, nested query denial-of-service, field-level authorization bypass, and subscription hijacking. Covers Apollo Server, graphql-yoga, Strawberry, Graphene, gqlgen, and HotChocolate.

Activation

Called by sc-orchestrator during Phase 2 when GraphQL schema files, resolvers, or GraphQL dependencies are detected.

Phase 1: Discovery

File Patterns to Search

**/*.graphql, **/*.gql, **/schema.*, **/typeDefs.*, **/resolvers.*,
**/*resolver*, **/*schema*, **/*graphql*, **/mutations/*, **/queries/*,
**/subscriptions/*, **/directives/*

Keyword Patterns to Search

"typeDefs", "resolvers", "ApolloServer", "graphql-yoga", "makeExecutableSchema",
"buildSchema", "@Query", "@Mutation", "@Resolver", "GraphQLObjectType",
"introspection", "depthLimit", "costAnalysis", "complexityLimit",
"__schema", "__type", "subscription", "directive"

Security Checks

1. Introspection Enabled in Production

• Check if introspection is explicitly disabled in production config
• Search for: introspection: true, missing introspection config, NODE_ENV checks

2. Query Depth/Complexity Limits Missing

• Check for depth limiting middleware: graphql-depth-limit, depthLimit, @complexity
• Check for query cost analysis: graphql-query-complexity, costAnalysis
• Absence of both = vulnerable to nested query DoS

3. Batching Without Limits

• Check if query batching is enabled without limits
• Search for: allowBatchedHttpRequests, batch query handler, array query acceptance

4. Field-Level Authorization

• Check if resolver functions verify user permissions
• Search for missing auth checks in mutation resolvers
• Check directive-based auth: @auth, @hasRole, @authenticated

5. SQL/NoSQL Injection in Resolvers

• Trace GraphQL arguments through resolver to database queries
• Check if arguments are used in raw queries without parameterization

6. Information Disclosure via Error Messages

• Check if detailed error messages are returned to clients
• Search for: formatError, debug: true, stack trace exposure

7. Subscription Authorization

• Check WebSocket subscription handlers for auth validation
• Verify subscription filters don't leak data to unauthorized users

Phase 2: Verification

Nested Query DoS Example

# Attack: Deeply nested query (no depth limit)
query {
  user(id: 1) {
    posts {
      author {
        posts {
          author {
            posts { # ...repeating to depth 50+
              title
            }
          }
        }
      }
    }
  }
}

// VULNERABLE: No depth or complexity limits
const server = new ApolloServer({
  typeDefs,
  resolvers,
});

// SAFE: With depth and complexity limits
import depthLimit from 'graphql-depth-limit';
import { createComplexityLimitRule } from 'graphql-validation-complexity';

const server = new ApolloServer({
  typeDefs,
  resolvers,
  validationRules: [
    depthLimit(10),
    createComplexityLimitRule(1000),
  ],
  introspection: process.env.NODE_ENV !== 'production',
});

Authorization Bypass Example

// VULNERABLE: No auth check in resolver
const resolvers = {
  Mutation: {
    deleteUser: async (_, { id }, context) => {
      return await User.findByIdAndDelete(id); // Anyone can delete any user
    }
  }
};

// SAFE: Auth check in resolver
const resolvers = {
  Mutation: {
    deleteUser: async (_, { id }, context) => {
      if (!context.user || context.user.role !== 'admin') {
        throw new ForbiddenError('Not authorized');
      }
      return await User.findByIdAndDelete(id);
    }
  }
};

Severity Classification

• Critical: SQL/NoSQL injection through GraphQL arguments, authentication bypass in mutations
• High: Missing field-level authorization on sensitive mutations, introspection enabled exposing internal schema in production
• Medium: Missing query depth/complexity limits (DoS risk), batching abuse, subscription data leaks
• Low: Verbose error messages, introspection enabled in staging, missing rate limiting on queries

Output Format

Finding: GQL-{NNN}

• Title: {GraphQL vulnerability type}
• Severity: Critical | High | Medium | Low
• Confidence: 0-100
• File: file/path:line
• Vulnerability Type: CWE-89 (Injection) | CWE-200 (Information Disclosure) | CWE-862 (Missing Authorization) | CWE-770 (Resource Exhaustion)
• Description: {What was found}
• Proof of Concept: {Example query demonstrating the issue}
• Impact: {What happens if exploited}
• Remediation: {How to fix with code example}
• References: https://cheatsheetseries.owasp.org/cheatsheets/GraphQL_Cheat_Sheet.html

Common False Positives

1. Introspection in development — introspection is expected in dev/staging environments
2. Public queries without auth — some queries are intentionally public (e.g., product listings)
3. Depth limits in gateway — depth limiting may be enforced at the API gateway level, not in the GraphQL server
4. Schema-first codegen — generated resolvers may appear to lack auth but are wrapped by middleware
5. Federated schemas — auth may be handled by the gateway in a federated GraphQL architecture