Expert API security testing from Bulletproof
API Security Testing
Comprehensive API penetration testing to assess authentication, authorisation, configuration, business logic flaws, and more across REST, SOAP, and GraphQL APIs.
Crest Certified Security Experts
Our pen testers are independently certified by industry recognised bodies such as CREST, ensuring expert API security testing.
Data Driven Security Insights
Access clear, prioritised risk reports via our intuitive threat dashboard, helping you fix vulnerabilities faster.
Continuous API Security Monitoring
Ongoing API security testing to identify and remediate new vulnerabilities as they emerge, keeping your business protected 24/7.
Why API security testing is essential
API penetration testing simulates real-world cyberattacks to uncover vulnerabilities in API authentication, authorisation, and data handling. Using the same up-to-date attack techniques as malicious hackers, Bulletproof’s API security experts assess REST, SOAP, and GraphQL APIs for security weaknesses, misconfigurations, and business logic flaws. Regular API penetration testing is essential to prevent data breaches and ensure a robust security posture.
Bulletproof pen testers use their expertise in how to penetration test web applications to carry out static source code reviews such as Static Application Security Testing (SAST), and Dynamic Application Security Testing (DAST). DAST simulates an attack on the application when it’s running, meaning security weaknesses can be detected that only occur under certain conditions or operating scenarios. DAST and SAST are integral parts of securing your software development lifecycle (SDLC).
API security testing
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Input Validation
Prevent SQL injection, Cross-Site Scripting (XSS) & Cross-Site Request Forgery (CSRF)
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API Security Testing
Rigorously test the security of your APIs (Application Programming Interfaces)
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Secure API Data Handling
Ensure APIs securely handle sensitive data to prevent exposure, insecure object references, and leaks
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Encryption & Transportation
Ensure API requests and responses are securely encrypted with strong ciphers and correct implementation
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Error Handling
Verify API errors handling does not disclose sensitive information that could be useful to attackers
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Security Patching
Ensure all areas of your web apps and APIs are up to date with known security vulnerabilities
Benefits of API penetration testing
Bulletproof’s CREST certified penetration testers conduct in-depth security assessments of your APIs to systematically uncover vulnerabilities. Our testing follows industry best practices, such as OWASP API Security Top 10, ensuring your APIs remain resilient against evolving cyber threats. Our detailed reports provide both an executive summary for key stakeholders and a technical breakdown for development teams. Expose vulnerabilities and misconfigurations in API endpoints.
- Identify authentication and authorisation flaws
- Reveal insecure API logic and excessive data exposure
- Detect security design weaknesses in your API architecture
We recognise how constantly evolving threats can impact your security, which is why we offer 12 months of free vulnerability scanning on up to 8 IP addresses when you book an API penetration test.
Get a quoteTypes of API penetration testing
API penetration testing models different attack scenarios to uncover vulnerabilities in authentication, authorisation, and data exposure. Bulletproof recommends a combination of authenticated and unauthenticated testing to fully assess API security risks.
Authenticated API Testing
Authenticated (white box) pen testing assesses security from the perspective of a compromised or malicious user with valid API credentials. This method helps uncover access control issues, privilege escalation risks, and excessive data exposure.
Unauthenticated API Testing
Unauthenticated (black box) pen testing simulates an external attacker attempting to exploit exposed API endpoints. This type of testing is critical for identifying misconfigurations, broken authentication, and publicly exposed data.
Integrated API Security Testing
APIs are often the backbone of web and mobile applications, making API security testing a vital process. While API security is frequently included within broader web app penetration tests, dedicated API penetration testing provides deeper insights into API-specific threats.
Top 10 API security vulnerabilities
The most common API security vulnerabilities identified during pen testing:
- Improper API Authentication and Access Controls
- Broken Object-Level Authorisation (BOLA)
- Excessive Data Exposure
- Lack of Rate Limiting
- Injection Attacks (SQLi, XMLi, JSONi, Command Injection)
- Insecure API Key Management
- API Security Misconfigurations
- Unrestricted File Upload
- Server-Side Request Forgery (SSRF)
of web vulnerabilities are a low effort to fix
high likelihood of being exploited
API Penetration Testing Methodology
Most API penetration testing engagements follow a structured 6-step lifecycle:
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Scope definition & pre-engagement interactions
We collaborate with your team to define API testing objectives, identify critical endpoints, and establish a tailored testing strategy that aligns with your business needs.
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Intelligence gathering & threat modelling
In this reconnaissance phase, our experts analyse API documentation, publicly exposed endpoints, and authentication mechanisms to identify potential attack surfaces.
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Vulnerability analysis
Using industry-leading tools and manual testing techniques, our penetration testers analyse API requests, responses, authentication flows, and security controls to uncover vulnerabilities.
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Exploitation
We attempt to bypass authentication, manipulate API parameters, and exploit misconfigurations using a mix of custom scripts and automated testing tools - while ensuring no disruption to your business.
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Post-exploitation & lateral movement
Once an API vulnerability is exploited, we assess the real-world impact by attempting privilege escalation, unauthorised data access, or chaining attacks to simulate a full compromise scenario.
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Reporting & remediation guidance
Our security team delivers a detailed API penetration test report, including an executive summary and technical breakdown. We then conduct a collaborative review session to answer questions and provide remediation guidance.
Here’s what our customers say about us
We approached Bulletproof as one of several suppliers who offer penetration testing services. Out of all those contacted, Bulletproof were by far the most professional and slick to work with. From start to finish, the whole process was painless and ran like clockwork. The conclusive pen test report was succinct with clear steps of resolution provided. We were genuinely impressed with how easy Bulletproof were to work with, and would definitely recommend.
This was a very straightforward process. I had enough information up front to understand the process, and did not need to ask many questions along the way. Great service!
Get a fast API pen test quote
One of our expert web app pen test consultants will get back to you as soon as possible.
API Security Testing FAQs
API penetration testing is a comprehensive security assessment where our specialist CREST certified penetration testers simulate real-world attacks on your API. Identifying vulnerabilities in authentication, authorisation, input validation, and data exposure through API penetration testing helps ensure that your APIs remain secure against cyber threats.
The duration of an API penetration test depends on the size and complexity of the API, the number of endpoints, and authentication mechanisms. More complex APIs with multiple endpoints, user roles, and integrations require more testing time. After defining the scope and objectives, Bulletproof provides a tailored timeline for the assessment.
To ensure a thorough API security assessment, we need key details about your API, such as: API documentation, authentication methods, API endpoints and parameters to be tested, whether the test will be authenticated or unauthenticated, and the desired security objectives and compliance requirements.
WBulletproof follows industry best practices, including the OWASP API Security Top 10, to assess API security. Our tests identify vulnerabilities such as:
- Broken authentication and access controls.
- Injection attacks.
- Excessive data exposure.
- Rate limiting and denial-of-service (DoS) risks.
- Security misconfigurations.
We use a blend of automated tools and manual testing to uncover security flaws that could be exploited in real-world attacks.
TWhile all API penetration tests aim to uncover security weaknesses, there are different testing approaches:
- Authenticated API Testing: Simulates an attacker with valid credentials to test access control flaws and privilege escalation risks.
- Unauthenticated API Testing: Assesses the public attack surface, identifying vulnerabilities that can be exploited without authentication.
- Business Logic Testing: Analyses how APIs process and enforce security rules, uncovering flaws in workflows and authorisation logic.
Bulletproof recommends a combination of these testing types to ensure full coverage of security risks.
Related resources
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