API Penetration Testing

APIs have become the backbone of modern digital infrastructure — powering mobile apps, third-party integrations, microservices, and partner ecosystems. But API security is frequently an afterthought, and the consequences are severe. API penetration testing is a specialized security assessment focused on REST, GraphQL, SOAP, and gRPC interfaces, examining authentication mechanisms, authorization controls, rate limiting, data exposure, and injection vulnerabilities according to the OWASP API Security Top 10. Unlike general web application testing, API assessments require specific tooling and expertise to reconstruct undocumented endpoints, test mass assignment vulnerabilities, and analyze token-based authentication flows.

The OWASP API Security Top 10 reads like a catalog of real-world breaches: Broken Object Level Authorization (BOLA) allowed attackers to access any user's data in dozens of major platforms; Broken Authentication exposed millions of accounts through weak token validation; Excessive Data Exposure sent sensitive fields to the client that the application never intended to display. Many of these vulnerabilities are invisible in the browser but trivially discoverable with an API testing proxy. API-first architectures amplify risk because a single compromised API endpoint can expose data across every client — web, mobile, and third-party — simultaneously.

BugFoe's API security testers begin every engagement with thorough endpoint discovery, even for undocumented internal APIs. We test authentication and token security using both valid credentials and malformed tokens. Authorization testing verifies that horizontal and vertical privilege boundaries are properly enforced across every endpoint. We specifically test for GraphQL-specific risks including introspection abuse, batching attacks, and deeply nested query DoS. All findings include request/response demonstrations, curl commands for reproducibility, and code-level remediation guidance. For teams using OpenAPI/Swagger specifications, we use your spec as an additional testing baseline to identify specification-implementation divergence.