What API types and protocols do you test?

We test REST, GraphQL, SOAP, and gRPC APIs. Testing covers OWASP API Security Top 10 risks including broken object-level authorization, excessive data exposure, mass assignment, and improper rate limiting.

Do you need access to our API documentation or source code?

We work in both black-box and white-box modes. Providing API documentation (OpenAPI/Swagger specs) allows more thorough coverage, but we can also discover and map undocumented endpoints as part of the engagement.

How do you test APIs that use OAuth 2.0 or JWT authentication?

We specifically evaluate token issuance, validation, and expiry logic. Common findings include weak JWT signing keys, missing audience validation, and OAuth misconfigurations that allow token theft or privilege escalation.

Our API is only accessible internally — can you still test it?

Yes. We can conduct testing via VPN access to your internal environment, or perform on-site testing if required. Internal APIs often have weaker controls and are a common lateral movement target once an attacker is inside the network.

What is the typical finding rate for API penetration tests?

API testing consistently surfaces high-severity findings in organizations with mature web security programs, because API security controls often lag behind front-end security. Common critical findings include BOLA, unauthenticated endpoints, and sensitive data in responses.

OWASP API Top 10

API Penetration Testing

Expert testing of REST, GraphQL, and SOAP APIs to identify authentication flaws, injection vulnerabilities, and data exposure risks. Secure your API backbone.

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Coverage

API Security Testing Areas

Complete coverage of API-specific attack vectors

REST API Testing

Complete testing of RESTful endpoints including authentication, rate limiting, and data validation

GraphQL Security

Deep analysis of GraphQL schemas, queries, mutations, and introspection vulnerabilities

BOLA/IDOR Detection

Broken Object Level Authorization testing to prevent unauthorized data access

Authentication Bypass

JWT manipulation, OAuth flaws, API key security, and token handling issues

Rate Limit Testing

Brute force protection, resource exhaustion, and denial of service resistance

Data Exposure

Excessive data exposure, sensitive information leakage, and improper error handling

Process

Our API Testing Methodology

Systematic approach following OWASP API Security guidelines

API Discovery

Enumerate all endpoints, parameters, and authentication mechanisms

Authentication Testing

Test API keys, tokens, OAuth flows, and session management

Authorization Testing

BOLA, BFLA, and function-level access control testing

Input Validation

Injection attacks, mass assignment, and parameter tampering

Rate Limiting

Test throttling, resource limits, and abuse prevention

Documentation Review

Analyze OpenAPI specs for security misconfigurations

Deliverables

What You Receive

Complete API endpoint inventory
OWASP API Top 10 vulnerability assessment
Authentication mechanism analysis
Rate limiting and abuse prevention report
Remediation prioritization matrix
API security best practices guide

How it works

What an API Penetration Test Looks Like

Scoped on endpoints and roles, executed against the specification and beyond it

Scoping from the specification

We ask for the OpenAPI, Swagger, GraphQL schema, or Postman collection up front and scope on the number of endpoints, authentication schemes, and consumer types (first-party web or mobile client, partner integration, public developer API). Undocumented endpoints discovered during testing are in scope by default because they are exactly where the risk lives.

Typical effort: 4 to 7 testing days for an API of 30 to 80 endpoints with two or three roles.
Access we need: credentials or tokens for every role, a non-production base URL or a production window, and the specification file.
Coverage guarantee: every documented endpoint is exercised with every role, and the report lists the ones that produced no finding.

Testing the way an integrator would attack it

API tests are run without a browser in the way. We replay and mutate real client traffic, test each endpoint with a token from the wrong role, remove and downgrade authentication, and fuzz object identifiers, filters, and pagination parameters. GraphQL gets introspection, batching, alias-based brute force, and depth-limit tests in addition to the REST checks.

Evidence your backend engineers can act on

Each finding ships as a reproducible request, the exact response that proves it, and a remediation phrased at the framework or gateway layer, whether that is a policy in your API gateway, an authorisation check in a resolver, or a schema constraint.

Retest and attestation

Critical and high findings are retested within 30 days at no cost. The final letter confirms the retest date and outcome for each finding so it can be attached to a partner security review.

Coverage

Vulnerability Classes We Test For

Aligned to the OWASP API Security Top 10 and what we actually find in the field

Broken object and function level authorisation

The most common critical finding in API tests. We enumerate every identifier in every endpoint across every role and confirm whether the server checks ownership. Administrative functions reachable by ordinary tokens, and property-level authorisation where a user can update fields they should only read, are tested with the same rigour.

Authentication and token handling

JWT signature and algorithm confusion, weak signing keys, missing expiry and audience checks, API keys in URLs, refresh-token reuse, OAuth scope and redirect issues, and rate limiting on token issuance endpoints.

Resource consumption and rate limiting

Unbounded pagination, expensive queries and GraphQL depth, file-size and batch limits, and per-consumer throttling. These findings matter to availability and to cloud cost, and they are usually invisible to a web-focused test.

Injection, SSRF, and data exposure

Injection into datastores and downstream services, server-side request forgery through URL-accepting parameters, excessive data in responses that the client hides rather than the server withholds, and verbose error handling that leaks stack traces or internal hostnames.

Inventory and configuration

Old API versions still reachable, debug and health endpoints exposing internal state, permissive CORS, missing transport security on internal hops, and third-party integrations that trust the API more than they should.

Compliance

Standards and Compliance Mapping

Frameworks the test is mapped to

Every finding is tagged to the control it evidences, so the report drops straight into an audit pack instead of needing a second translation exercise. For API engagements the mappings we deliver by default are:

PCI DSS v4.0 Requirement 11.4: external and internal penetration testing on a defined methodology, with retest evidence for exploitable findings.
ISO/IEC 27001:2022 Annex A 8.8 (management of technical vulnerabilities) and A 8.29 (security testing in development and acceptance).
SOC 2 Common Criteria CC7.1 and CC4.1: vulnerability identification and independent evaluation of control effectiveness.
OWASP Web Security Testing Guide, OWASP ASVS, and PTES as the underlying methodology references cited in the report.
Regulatory expectations for reasonable security safeguards, including data-protection regimes such as the GDPR and India's DPDP Act, where the application handles personal data.

What auditors receive

The report includes a methodology statement, tester attestation, scope and exclusions, a findings register with CVSS v3.1 scores, evidence for each finding, and a signed retest letter once fixes are verified. Customers use the same pack for customer security questionnaires, cyber-insurance renewals, and procurement due diligence.

Further reading: API penetration testing methodology · API security testing guide for SaaS · OAuth 2.0 misconfigurations attackers exploit

FAQ

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