Specialized security assessment of your API infrastructure — REST, GraphQL, SOAP, and WebSocket endpoints. APIs are the backbone of modern applications, and I ensure yours are hardened against the unique attack vectors that target programmatic interfaces, from broken object-level authorization to mass data exposure.
APIs face a distinct threat landscape that traditional web application testing often misses. My API-focused methodology addresses the specific vulnerability classes outlined in the OWASP API Security Top 10.
End-to-end security assessment of RESTful API endpoints, including resource enumeration, HTTP method testing, parameter tampering, and response analysis. I validate that every endpoint enforces proper authentication, authorization, input validation, and rate limiting while ensuring that error responses do not leak sensitive implementation details.
Targeted testing of GraphQL APIs for introspection disclosure, query depth attacks, batching abuse, and authorization bypass through field-level access control weaknesses. I analyze resolver logic for injection vulnerabilities, test for denial-of-service through complex nested queries, and validate that schema exposure does not reveal sensitive internal data structures.
Deep analysis of OAuth 2.0 flows and JSON Web Token implementations for token leakage, signature validation bypass, algorithm confusion attacks, token replay, and scope escalation. I verify that refresh token rotation is properly implemented, that authorization codes cannot be reused, and that token expiration policies align with your security requirements.
Evaluation of rate limiting, throttling, and anti-abuse mechanisms across all API endpoints. I test for brute-force attack resilience on authentication endpoints, resource exhaustion through bulk operations, and business logic abuse through rapid successive requests that could lead to financial loss, data scraping, or denial-of-service conditions.
Identification of excessive data exposure where API responses return more data than the client application consumes. I analyze every endpoint's response payload for sensitive fields like internal IDs, email addresses, financial data, and PII that should be filtered server-side. This prevents data harvesting through API scraping even when the front-end masks the information.
Focused testing for Broken Object Level Authorization (BOLA) and Broken Function Level Authorization (BFLA) — the two most critical and prevalent API vulnerabilities. I systematically test every endpoint with manipulated object references and cross-role requests to verify that users cannot access or modify resources belonging to other users or perform administrative actions.
My API security testing methodology is purpose-built for programmatic interfaces, addressing the unique challenges of testing machine-to-machine communication channels where traditional browser-based testing tools fall short.
I begin by mapping the complete API surface — analyzing OpenAPI/Swagger specifications, intercepting mobile and web application traffic, and discovering undocumented endpoints through wordlist fuzzing and JavaScript source code analysis. Every endpoint, parameter, and authentication mechanism is catalogued to ensure nothing is missed during testing.
Thorough assessment of API authentication mechanisms — API keys, bearer tokens, OAuth flows, JWT implementations, and custom authentication headers. I test for credential stuffing resilience, token expiration enforcement, session invalidation after password changes, and whether authentication can be bypassed entirely on sensitive endpoints through direct object access.
Systematic validation of access controls across every endpoint and HTTP method combination. I test horizontal privilege escalation (accessing other users' data), vertical privilege escalation (performing admin functions as a regular user), and function-level authorization gaps. Each test uses multiple user roles to map the complete authorization matrix and identify gaps.
Testing all API input vectors — request bodies, query parameters, path parameters, and headers — for injection vulnerabilities including SQL injection, NoSQL injection, command injection, and SSRF. I also test for mass assignment, where attackers send additional parameters to modify fields they should not have access to, such as role or privilege attributes.
Delivery of a detailed API security report with every finding mapped to the OWASP API Security Top 10. Each vulnerability includes the affected endpoint, HTTP request/response pairs, exploitation proof-of-concept, CVSS score, and specific remediation code guidance. I provide a Postman collection of all test cases so your development team can revalidate fixes independently.
I combine specialized API testing tools with proxy-based interception and custom scripting to test complex authentication flows, chained requests, and business logic that automated scanners cannot replicate.
Securing your APIs is critical — they handle your most sensitive data flows and are increasingly the primary target for attackers. Professional API testing ensures your programmatic interfaces are as secure as your user-facing applications.
APIs are the most attacked surface in modern applications. Let's assess your API security posture, identify vulnerabilities, and deliver a clear remediation roadmap tailored to your architecture. Every engagement starts with a free scoping call.
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