API Security Check

Focused security testing for your APIs — fixed scope, clear results

Targeted API testing

Not every application needs a full all-layers pentest. Sometimes you have a backend API, a partner integration, or a set of microservices that need a focused security check — without the scope and timeline of a comprehensive engagement.

The API Security Check is a fixed 2-day assessment focused exclusively on your API endpoints and their security controls. I test authentication and authorization mechanisms, input validation, business logic, data exposure, and abuse potential across REST, GraphQL, gRPC, or WebSocket interfaces.

What I test

The assessment covers the OWASP API Security Top 10 and dynamically goes beyond it where the specific API warrants deeper checks:

  • Authentication and token handling: OAuth flows, JWT validation and expiry, API key management, token lifecycle, session binding
  • Authorization: broken object-level authorization (BOLA), broken function-level authorization, horizontal and vertical privilege escalation between API consumers
  • Input validation: injection attacks across all input vectors, parameter tampering, mass assignment, type confusion
  • Data exposure: excessive data in responses, verbose error messages, information leakage through headers or metadata
  • Rate limiting and abuse: resource exhaustion, enumeration attacks, brute-force potential, missing or bypassable rate limits
  • Business logic: state manipulation in multi-step API workflows, race conditions, order-of-operations abuse

Where relevant, I also check for technology-specific issues like GraphQL introspection exposure, batching abuse, or gRPC reflection misconfigurations.

How it works

  1. Scoping call: We agree on the API scope, access details, and any areas of particular concern. You share API documentation (OpenAPI/Swagger specs, Postman collections, or similar) and I confirm the assessment plan.
  2. Testing: I run the assessment independently. If I need clarification during testing, I reach out via email or chat.
  3. Report delivery and debrief: You receive the written report ahead of a debrief call where I walk through the findings with your development team, answer questions, and discuss remediation priorities.

Prerequisites

  • API documentation or OpenAPI/Swagger specification (at minimum: a list of endpoints and their expected parameters)
  • Access to a test environment with representative data
  • Two sets of API credentials with different permission levels (e.g., regular user and admin, or two different tenants)
  • A technical contact for questions that may arise during testing

This service also supports technical security requirements commonly referenced in modern cybersecurity regulations.

When to choose this vs. an application pentest

The API Security Check is scoped to API endpoints and their security controls. If you also need testing of the frontend application, session management, client-side logic, or the full application stack, the Application Pentest is the better fit.

Interested in your individual quote? Let’s talk