Modern applications are more than just web pages. They are ecosystems of microservices and APIs. While application penetration testing is a proven way to find flaws, API security testing has become just as critical. Here is how they compare and why you likely need both.
Application Penetration Testing
This focuses on the entire web application from the perspective of a user. Testers look for vulnerabilities in the UI, session management, and how the app interacts with the backend.
- Scope: The complete user journey and interface.
- Flaws: XSS, CSRF, insecure direct object references, and logic flaws in the browser.
- Goal: Ensure a malicious user cannot compromise other accounts or the server via the UI.
API Security Testing
This focuses on the headless part of your stack. APIs are the connective tissue of modern software and they often have a different set of risks.
- Scope: REST, GraphQL, or SOAP endpoints used by mobile apps, SPAs, or third parties.
- Flaws: Mass assignment, broken object level authorization, rate limiting issues, and data exposure.
- Goal: Ensure that direct calls to the API cannot bypass security controls or leak data.
Why Both Matter
Many teams assume that testing the web app covers the API. This is a mistake. An API might expose functionality that the UI never uses. Attackers will bypass your UI entirely and talk directly to your endpoints.
- Headless attacks: Attackers use tools like Burp Suite or Postman to probe endpoints directly.
- Mobile vs Web: Your mobile app might use different API versions than your web app.
- Partner access: If you expose APIs to partners, you need to ensure they are properly scoped and secure.
A Unified Approach
A complete security assessment should cover both the front door and the back door.
- Use web application penetration testing for your customer facing interfaces.
- Use API security testing for every endpoint your developers have built.
- Focus on the OWASP API Top 10 specifically for your services.
By testing the full stack, you close the gaps that attackers love to exploit. Ready for an assessment? Contact our application security team.