API Security Testing Chennai: REST vs GraphQL Protection

Introduction

APIs are no longer just connectors—they are the backbone of digital business. From mobile banking apps and healthcare platforms to e-commerce and SaaS, APIs run the modern world. According to research, 90% of web-enabled applications rely on APIs, and by 2026, the global API security market is expected to exceed $10 billion.

But here’s the challenge: as APIs grow in power, they also grow in attack surface. Attackers don’t need to hack your web app—they just need to exploit your API.

Two major API styles dominate today:

• REST (Representational State Transfer) – widely used, resource-based.
• GraphQL – newer, flexible, query-driven.

Both are powerful—but both come with unique security challenges.

This guide explores API security testing for REST and GraphQL, helping you understand:

• How attackers exploit each API style.
• Testing strategies for finding vulnerabilities.
• Real-world case studies of API breaches.
• Best practices for securing APIs at scale.

By the end, you’ll know when to use REST vs GraphQL, and how to protect them both.

🔹 Why API Security Testing Matters

📈 API Growth = Bigger Target

• Every mobile app, SaaS platform, IoT device, and fintech solution relies on APIs.
• Attackers know that APIs often bypass traditional security layers.

⚠️ Real-World API Breaches

1. T-Mobile API Breach (2021–2023)
   • Multiple API flaws exposed customer data.
   • Over 37 million customer records leaked.
   • Root cause: insufficient authentication & rate limiting.
2. Facebook (Cambridge Analytica case)
   • Facebook APIs over-exposed data.
   • Third parties harvested millions of user profiles.
   • Root cause: excessive data exposure.
3. Shopify API Vulnerability (2020)
   • Researchers found GraphQL API misconfigurations.
   • Attackers could query internal systems.
   • Root cause: improper field-level authorization.

👉 Lesson: APIs are the new crown jewels. If you don’t test them, attackers will.

🔹 REST APIs – Security Testing Essentials

What is REST?

• REST is the most common API style, using HTTP verbs (GET, POST, PUT, DELETE).
• Data is usually returned in JSON.
• Each resource has its own endpoint (/users/123, /orders/456).

Common Security Risks in REST APIs

1. Broken Authentication
   • Weak tokens, exposed API keys.
   • Example: JWTs without signature validation.
2. Broken Authorization (IDOR)
   • Example: /users/123 → change ID to /users/124.
   • If access isn’t checked, attacker reads other users’ data.
3. Excessive Data Exposure
   • API returns full user record, not just required fields.
   • Developers rely on front-end to filter—bad practice.
4. Injection Attacks
   • SQL, NoSQL, command injection through parameters.
5. Rate Limiting & DoS
   • No protection = brute force or resource exhaustion.

REST API Security Testing Strategies

1. Authentication Testing
   • Try weak JWTs, missing exp (expiry).
   • Test API key leakage.
2. Authorization Testing
   • Perform IDOR tests by modifying object IDs.
   • Example: change /accounts/1001 to /accounts/1002.
3. Input Validation Testing
   • Use fuzzing tools for SQLi, NoSQLi, XSS in parameters.
4. Rate Limiting Tests
   • Send hundreds of login attempts → check lockout.
5. Error Handling Checks
   • Trigger errors → see if API leaks DB version or stack traces.

Tools for REST API Security Testing

• Burp Suite Pro → parameter tampering, replaying requests.
• Postman → manual API testing.
• OWASP ZAP → automated scanning.
• Nmap + NSE scripts → endpoint discovery.
• APIsec, StackHawk → automated CI/CD API testing.

🔹 GraphQL APIs – Security Testing Essentials

What is GraphQL?

• Developed by Facebook.
• Instead of multiple endpoints, one single endpoint (/graphql) handles all queries.
• Clients request exactly the data they need.

Looks efficient, right? But it opens new security risks.

Common Security Risks in GraphQL

1. Excessive Data Exposure
   • Developers expose too much in the schema.
   • Attackers fetch sensitive fields not intended for clients.
2. Denial of Service (DoS)
   • Recursive queries → infinite loops.
   • Example: friends { friends { friends } }.
3. Broken Authorization
   • Even if the endpoint exists, field-level checks are missing.
   • Example: regular user accessing isAdmin flag.
4. Introspection Abuse
   • GraphQL introspection reveals entire schema.
   • Attackers use it for reconnaissance.
5. Injection Attacks
   • GraphQL queries can still be abused like SQL injection.

GraphQL Security Testing Strategies

1. Disable or Restrict Introspection in production.
   • Only allow in development/test environments.
2. Authorization Testing
   • Check every field and mutation for access control.
3. Query Depth & Complexity Testing
   • Test nested queries.
   • Ensure query complexity limits are enforced.
4. Fuzzing GraphQL Queries
   • Inject unexpected inputs.
   • Example: query for hidden admin fields.
5. Error Message Analysis
   • Ensure no stack traces or schema leaks.

Tools for GraphQL Security Testing

• GraphQLmap → like SQLmap for GraphQL.
• InQL (Burp Extension) → query generation, introspection.
• Postman → GraphQL requests.
• Escape, GraphQL-Cop → automated scanners.

🔹 REST vs GraphQL – Key Security Differences

👉 REST = Endpoint-centric security.
👉 GraphQL = Query-centric security.

🔹 Best Practices for API Security Testing

1. Follow OWASP API Security Top 10.
2. Strong Authentication & Authorization (OAuth2, JWT best practices).
3. Rate Limiting & Throttling.
4. Schema Validation (OpenAPI for REST, SDL for GraphQL).
5. Input Sanitization to prevent injection.
6. Automated Testing in CI/CD pipelines.
7. Regular Penetration Testing by experts.
8. Monitor APIs with SIEM/SOC tools.

🔹 Case Study – REST API Breach

A fintech company exposed /accounts/{id} API.

• No proper authorization checks.
• Attackers changed IDs → accessed other customers’ accounts.
• Result: financial data breach, compliance failure.

👉 Lesson: Always enforce object-level authorization.

🔹 Case Study – GraphQL Breach

A SaaS platform left introspection enabled in production.

• Attackers mapped the schema → discovered hidden admin fields.
• Exploited isAdmin flag to escalate privileges.
• Result: full admin account takeover.

👉 Lesson: Lock down introspection & field-level authorization.

🔹 Conclusion

APIs power the digital world—but they also expose businesses to massive risks if not tested properly.

• REST APIs are more endpoint-driven, requiring strong checks on tokens, parameters, and rate limiting.
• GraphQL APIs are more flexible but riskier, requiring query-level security, depth control, and schema protection.

Security isn’t just about building APIs—it’s about testing them continuously.

📢 Codesecure: Your Cybersecurity Partner

At Codesecure, we specialize in API security testing—covering REST, GraphQL, SOAP, and custom APIs. Whether you’re building SaaS, fintech, or healthcare apps, our experts help you identify vulnerabilities before attackers do.

For inquiries and consultation:

📞 Call us: +91 7358463582
📧 Email us: [email protected]
🌐 Visit us: www.codesecure.in

Stay secure, stay API-ready!