// API Security Testing — REST · GraphQL · SOAP · gRPC

Your API is an
Open Door for Attackers

APIs are the backbone of every modern app — and the #1 target for data breaches. CyberHQ's manual API security testing finds what automated scanners completely miss: broken authorization, business logic flaws, and hidden attack vectors.

83%
Of breaches involve APIs
OWASP
API Top 10 Aligned
REST+
GraphQL · gRPC · SOAP
48hr
Report Turnaround
Book API Security Audit See Methodology

// Understanding API Threats

Why APIs Are Your Biggest Blind Spot

APIs expose your core business logic directly to the internet. Unlike web applications, APIs often skip input validation, return excessive data, and have inconsistent access controls — making them a goldmine for attackers.

Modern apps use hundreds of API endpoints. A single misconfigured endpoint can expose every user's data, allow account takeover at scale, or let an attacker access admin functionality without any credentials.

Tests REST, GraphQL, SOAP, gRPC, and WebSocket APIs

Identifies BOLA/IDOR at scale across all object types

Exposes broken authentication — JWT attacks, token reuse, key leakage

Tests business logic and rate limiting bypasses other firms miss

cyberhq@api-audit:~$ ./api_scan.py --target api.target.com

[*] Discovering API endpoints via Swagger + fuzzing...

[+] Found 134 endpoints (12 undocumented)

[*] Testing BOLA on /api/v1/users/{id}...

[CRITICAL] BOLA: User A can access User B's data

[*] Testing JWT manipulation...

[CRITICAL] Algorithm confusion: RS256 → HS256 bypass

[HIGH] /admin/export has no auth check

[HIGH] Mass assignment on /api/users/update

[*] Testing rate limiting...

[+] OTP brute force: no rate limit found

[✓] 18 findings total: 3 Critical, 7 High, 8 Medium

// OWASP API Security Top 10

The API Attack Landscape

OWASP's API Security Top 10 defines the most critical risks. We test ALL of them — manually.

API1
Broken Object Level Authorization (BOLA)
API2
Broken Authentication
API3
Broken Object Property Level Auth
API4
Unrestricted Resource Consumption
API5
Broken Function Level Authorization
API6
Unrestricted Access to Sensitive Business Flows
API7
Server Side Request Forgery (SSRF)
API8
Security Misconfiguration
API9
Improper Inventory Management
API10
Unsafe Consumption of APIs
83%

of organizations experienced an API-related security incident in 2023

Salt Security Report 2024

+167%

increase in API attacks year-over-year — fastest growing attack vector

Akamai State of Internet 2024

91%

of APIs have at least one vulnerability that exposes sensitive data

Noname Security 2024

// Comprehensive API Coverage

What We Test & Cover

Authorization Flaws

  • › BOLA — access any object by changing ID
  • › BFLA — user calling admin-only endpoints
  • › Horizontal & vertical privilege escalation
  • › Tenant isolation bypass (SaaS apps)
  • › Mass assignment & parameter pollution

Authentication Attacks

  • › JWT algorithm confusion (RS256 → HS256)
  • › JWT none algorithm bypass
  • › API key leakage (GitHub, logs, responses)
  • › OAuth token hijacking & CSRF
  • › Session token reuse after logout

Injection & Data Exposure

  • › NoSQL injection (MongoDB operators)
  • › GraphQL introspection & query injection
  • › Excessive data exposure in responses
  • › SSRF via API request chaining
  • › XXE in XML-based API endpoints

Business Logic

  • › Rate limit bypass (header manipulation)
  • › OTP/2FA brute force via API
  • › Price/quantity manipulation
  • › Race conditions in financial APIs
  • › Workflow bypass (skip payment step)

GraphQL Specific

  • › Introspection enabled in production
  • › Batching & aliasing attacks (DoS)
  • › Deep query nesting (resource exhaustion)
  • › Field suggestion abuse
  • › Mutation authorization bypass

Configuration & Inventory

  • › Shadow/zombie API discovery
  • › Deprecated API version attacks
  • › CORS misconfiguration
  • › Error message information leakage
  • › Missing security headers on API responses
// Execution Lifecycle

API Security Testing Methodology

OWASP API Security Top 10 Deep Assessment Framework

PHASE 01 STAGE 1/5
kiterunner — API Route Enumeration
[+] Discovered 128 REST endpoints & 2 GraphQL roots
[!] Found unauthenticated shadow route: /api/v1/internal/users
[INFO] Swagger schema extracted: /api/v2/swagger.json

Endpoint & Schema Discovery

Cataloging all published and hidden shadow/zombie endpoints by analyzing OpenAPI specs, Postman collections, and brute-force route fuzzing.

Swagger-ParserKiterunnerBurp Suite Pro
PHASE 02 STAGE 2/5
jwt_tester.py — Object Authorization
[CRIT] BOLA Confirmed: GET /api/v2/invoices/INV-9021
[*] User A token successfully fetched User B invoice
[HIGH] JWT algorithm confusion: alg: none accepted by server

BOLA & Authentication Testing

Testing object-level and function-level authorization across multiple JWT tokens to access unauthorized tenant records and admin endpoints.

AutorizeJWT_ToolPostman
PHASE 03 STAGE 3/5
payload_fuzz.json — Parameter Pollution
[*] Injecting extra params into PUT /api/users/profile
[CRIT] Mass Assignment: Added "role": "admin" accepted
[+] Privilege escalated from normal user to System Admin

Mass Assignment & Business Logic

Testing excessive data exposure, mass assignment parameter injection, GraphQL deep nested query DoS, and payment gateway logic flaws.

GraphQL-CopTurbo IntruderPostman
PHASE 04 STAGE 4/5
microservice_probe.py — Backend Testing
[!] Testing webhook URL on POST /api/v2/webhooks
[CRIT] Blind SSRF: Internal Redis server (port 6379) accessed
[✓] Internal microservices mesh reachable from API

Backend Injection & SSRF Attacks

Testing API backend microservices for NoSQL injection, XML external entity (XXE), and server-side request forgery (SSRF).

InteractshBurp CollaboratorNoSQLMap
PHASE 05 STAGE 5/5
gateway_policy.yaml — Rate Limiting & Auth
+ rate_limit: 100 req/min per IP | JWT strict signature enforced
[✓] Object-level authorization middleware code delivered
[✓] Free 30-day verification re-test included

API Gateway Hardening & Retest

Delivering API gateway rate-limiting policies, JWT validation middleware, and prioritized CVSS reports followed by a free re-test.

Kong / AWS API GatewayCVSS ScorecardFree Retest

Comprehensive Security Deliverables Included

Every engagement includes executive briefings, technical PoCs, code-level fix guidance, and a complimentary 30-day verification re-test.

Request Scope & Quote

// Real-World Impact

Case Study: FinTech Payment API

How we discovered a BOLA chain that could have allowed fraudulent fund transfers across 30,000+ accounts.

// THE SITUATION

Client Background

A Surat-based FinTech startup with a payment gateway API serving 30,000+ merchant accounts. They were preparing for RBI compliance audit and engaged CyberHQ for a black-box API security assessment before going to the auditors.

Target: REST API + Admin API
Scope: Black-box, 4 days
API type: REST + JWT auth

// CRITICAL FINDINGS

What We Discovered

  • [CRIT]BOLA on /api/transfers/{id} — any merchant can view ANY other merchant's transaction history
  • [CRIT]JWT algorithm confusion — forged admin token with RS256→HS256 attack, giving full admin access
  • [HIGH]No rate limit on /api/otp/verify — OTP brute forceable in 10,000 requests
  • [HIGH]Mass assignment on /api/users/update allowed self-promotion to admin role
// OUTCOME

Results

All 4 critical/high findings were fixed within 3 weeks with our guidance. CyberHQ re-tested and confirmed all fixes before the RBI audit.

30,000+ accounts protected from data exposure
RBI audit passed with zero findings
Fraudulent transfers prevented

// Secure Your APIs

Get Your API Security Audit

Share your API documentation or Swagger file — we'll scope the engagement and give you a clear timeline. No generic quotes.

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NDA Signed Before Engagement
All API Types Covered
Free Re-Test Included