API Penetration Testing
APIs expose business logic directly to the internet. Authentication flaws, authorisation gaps, rate limiting failures, and business logic abuse. We test against the OWASP API Security Top 10.
What Is API Penetration Testing?
API penetration testing is the process of identifying and exploiting security vulnerabilities in application programming interfaces. APIs are the connective tissue of modern software — they connect mobile apps to backends, microservices to each other, and third-party integrations to your core systems.
APIs expose business logic directly. Traditional web vulnerabilities apply, but APIs also introduce unique risks: broken object-level authorisation, excessive data exposure, mass assignment, and business logic abuse. We test for all of it against the OWASP API Security Top 10.
Scope of an API Pentest
Every protocol. Every endpoint. Every business logic path.
API Attack Surface
Endpoint enumeration, parameter tampering, HTTP method abuse, content-type manipulation, and endpoint discovery. Every API architecture — whether REST, GraphQL, or gRPC — brings its own documented attack patterns. We test across all of them.
Authentication & Authorization
Token manipulation, JWT exploitation, OAuth flow abuse, API key leakage, broken object-level authorisation (BOLA), and privilege escalation through endpoint access manipulation.
Rate Limiting & Abuse
Brute force potential, credential stuffing, enumeration attacks, resource exhaustion, and business logic abuse patterns that the API fails to prevent. Endpoints that can be called infinitely will be abused infinitely.
Business Logic
Workflow bypass, state manipulation, race conditions, and abuse of application-specific functionality. The vulnerabilities that no automated scanner can detect because they require understanding the business context.
Methodology
Four phases. Endpoint by endpoint.
API Discovery
Endpoint enumeration through documentation review, traffic interception, JavaScript analysis, directory brute-forcing, and parameter discovery. We map every endpoint before testing begins.
Vulnerability Identification
Manual testing of every endpoint against OWASP API Security Top 10. Parameter analysis, authorisation boundary testing, injection probing, and business logic evaluation across all roles and user types.
Exploitation
Demonstration of real impact. Data exfiltration through BOLA, privilege escalation chains, authentication bypass, and business logic abuse that shows financial or operational consequences.
Reporting
Findings documented with HTTP request/response evidence, CVSS ratings, and API-specific remediation guidance. Executive summary and technical detail tailored to development teams.
Our Technical Expertise
Standards and frameworks we test against.
OWASP API Top 10
The definitive reference for API security risks. Broken object-level authorisation, broken authentication, excessive data exposure, lack of rate limiting, broken function-level authorisation, mass assignment, security misconfiguration, injection, improper asset management, and insufficient logging.
Multi-Role Testing
Authorisation testing across all user roles and tenant boundaries. We verify that User A cannot access User B's data, that a standard user cannot reach admin endpoints, and that tenant isolation holds in multi-tenant systems.
Business Logic Expertise
The hardest class of API vulnerabilities to find. We learn the business context, then test whether an attacker could manipulate workflows, bypass payment steps, or access features without proper authorisation.
Request an API Pentest
Send us your API documentation. We'll scope the engagement and send a quote within 48 hours.