API Penetration Testing

Secure your REST APIs, web services and backend endpoints with expert-led API penetration testing. Blacklock identifies authentication, authorisation, business logic, data exposure and input validation weaknesses that could expose sensitive data or critical application functionality.

overview

A New Approach to API Security Assurance

APIs are the backbone of modern applications, mobileapps, SaaS platforms and integrations. They expose business logic, user dataand backend functionality that attackers often target directly.

Blacklock performs API penetration testing using acontrolled, checklist-based methodology aligned with OWASP and OSSTMM. Ourassessment combines automated vulnerability scanning with expert manual testingto identify vulnerabilities across API endpoints, request parameters,authentication flows, authorisation controls and backend interactions.

Our consultants review each API function from anattacker’s perspective, intercepting and manipulating requests, headers,parameters, tokens and workflows to uncover weaknesses that automated scannersmay miss.
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Our methodology

Our Approach to Comprehensive Assessment

Scoping & Target Specification
Understanding API & Workflow
Automated Security Vulnerability Scanning
Manual API Penetration Testing & Exploitation
Reporting & Ongoing Support
he scanning process we perform systematically
Scoping & Target Specification

We work with you to define the AI application scope, users, roles, workflows, LLM providers, APIs, tools, plugins, RAG pipelines, data sources, memory systems and testing objectives.

The scope can include chat interfaces, AI copilots, customer service bots, internal assistants, workflow automation tools, AI-enabled SaaS features and applications using OpenAI, Azure OpenAI, Anthropic, Bedrock, Gemini or self-hosted models.

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he scanning process we perform systematically
Understanding API & Workflow

Blacklock begins by reviewing API documentationprovided by the customer and performing test runs of API endpoints to confirmexpected behaviour.

Our consultants map endpoint functionality, requestmethods, parameters, headers, authentication flows, user roles, objectreferences and business logic. This phase helps identify parameters of interestand threats associated with API components and interfaces.

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he scanning process we perform systematically
Automated Security Vulnerability Scanning

Testing may include prompt injection suites, jailbreak pattern testing, harmful content checks, RAG poisoning simulation, tool schema fuzzing, rate limit review and API security scanning for authentication and authorisation weaknesses.

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he scanning process we perform systematically
Manual API Penetration Testing & Exploitation

Where the application integrates with APIs, databases, documents or business systems, we test whether the AI layer can be used to trigger unauthorised actions or expose sensitive data.

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he scanning process we perform systematically
Reporting & Ongoing Support

Blacklock delivers clear, actionable reports forexecutive, technical and developer audiences. Reports include an executivesummary, vulnerability details, proof of concept, evidence, risk rating, impactand remediation recommendations.

Where previous assessments exist, Blacklock can comparefindings to show remediation progress and recurring issues. Our team alsoprovides ongoing support to help developers understand and fix API vulnerabilities.

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about us

Why Us for API Penetration Testing?

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Deep API Security Coverage
Blacklock assesses API endpoints, authentication flows,authorisation controls, object references, headers, parameters, rate limits andbusiness logic to identify practical attack paths.
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Manual Testing Beyond Scanners
Automated tools are useful, but many APIvulnerabilities require manual exploitation. Blacklock validates findings andtests complex workflows that scanners often miss.
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OWASP-Aligned Methodology
Our API testing approach is aligned with OWASP API Top10 and OSSTMM, helping organisations assess APIs against recognised securitytesting standards.
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Our Team
Blacklock’s certified penetration testers bring deepexperience across APIs, web applications, mobile applications andinfrastructure. We focus on validated vulnerabilities, clear evidence andpractical remediation guidance.
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Endpoint Protection and Beyond

Our Services

Our Compliance Assurance Services
Web Application Penetration Testing
Discover vulnerabilities across public, internal andprivately hosted web applications and APIs. Blacklock combines automated DASTscanning, Agentic AI validation and expert-led manual penetration testing.
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Our Compliance Assurance Services
API Penetration Testing
Assess REST APIs, web services and backend endpointsfor authentication, authorisation, business logic, injection, data exposure andrate limiting vulnerabilities.
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Our Compliance Assurance Services
Mobile Application Penetration Testing
Identify security vulnerabilities across iOS andAndroid applications, application binaries, local storage, API endpoints,network communication and platform-specific controls.
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pricing plans

Precisely Curated Plans

Authenticated API Penetration Testing

14-Days Free Trial – Book Demo!Get Quote
Fit for APIs with users, roles and protected endpoints
Swagger, OpenAPI or Postman collection review
API documentation and workflow analysis
Authentication and session testing
Object-level and function-level authorisation testing
Parameter, header and token manipulation
Business logic exploitation
Injection and input validation testing
Rate limiting and resource abuse checks
Manual validation and proof of concept
Executive and technical reporting
Developer-ready remediation guidance
14-Days Free Trial – Book Demo!

Unauthenticated API Penetration Testing

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Fit for public APIs, open endpoints and unauthenticated services
Endpoint discovery and API behaviour review
Automated vulnerability scanning where appropriate
API misconfiguration testing
Excessive data exposure checks
Input validation and injection testing
Rate limiting and abuse case testing
Public object reference review
Supporting network-layer checks
Manual verification of findings
Risk-rated reporting
Remediation recommendations
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CUSTOMER TESTIMONIAL

Hear From Our Customers

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Secure your AI-powered applications with expert-led penetration testing across prompts, models, data, APIs, tools and workflows.

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Frequently Asked Questions (FAQs)

What is API Penetration Testing?
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API Penetration Testing is a controlled securityassessment of API endpoints, authentication, authorisation, parameters,headers, tokens and business workflows to identify vulnerabilities that couldexpose data or functionality.

What types of APIs can Blacklock test?
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Blacklock can test REST APIs, web services, mobile appAPIs, internal APIs, public APIs and APIs documented through Swagger, OpenAPIor Postman collections.

What API vulnerabilities are tested?
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Testing covers broken object level authorisation,broken function level authorisation, authentication bypass, privilegeescalation, excessive data exposure, injection, parameter manipulation, ratelimiting weaknesses and business logic flaws.

Is API testing automated or manual?
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Blacklock uses both automated scanning and manualpenetration testing. Automated results are manually reviewed and validated,while complex API workflows are tested manually from an attacker’s perspective.

What access is required?
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Access may include API documentation, Swagger orOpenAPI files, Postman collections, test credentials, user roles, API keys,tokens, test data and architecture information.

Do you test authenticated APIs?
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Yes. Blacklock can test authenticated APIs acrossmultiple user roles to identify authorisation weaknesses, privilege escalationand access control issues.

Do you test APIs used by mobile applications?
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Yes. API endpoints used by mobile applications can betested as part of API or mobile application penetration testing, depending onthe agreed scope.

How long does API Penetration Testing take?
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The duration depends on the number of endpoints, userroles, authentication flows, business workflows and testing depth. A standardAPI assessment typically takes several days to two weeks.

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