Checklist of the most important security countermeasures when designing, testing, and releasing your API. Use a fuzzer for discover new APIs. For several levels. Enumerate restricted endpoints. For trying to bypass. Add to the final endpoint(..;/, etc). Modifying the request for additional parameters. For example: &admin=true.

December 1, 2025 - API breaches happen because automated scanners can't detect business logic flaws. When T-Mobile exposed 37 million records, and Optus leaked 9.8 million customer details, both breaches stemmed from authorisation failures that no scanner flagged. This checklist provides 10 critical penetration tests that reveal the vulnerabilities attackers actually exploit, complete with testing methods, real breach examples, and the tools you need to find these issues before attackers do.

August 26, 2026 - Check if API permits credential stuffing where the attacker uses brute force with a list of valid usernames and passwords. Check if API permits attackers to perform a brute force attack on the same user account, without presenting captcha/account ...

August 11, 2025 - Check out the checklist of 154 test cases for comprehensive penetration testing of Android applications and verify that they don’t have any security loopholes. Read Article ... When conducting iOS application penetration testing, several key focus areas should be considered to ensure a comprehensive assessment. Read Article ... Join 51,000+ security leaders. Stay ahead of AI-driven attacks, API abuse, and bot threats with weekly insights and practical guidance.

2 days ago - Endpoint Discovery: Leverage API patterns to discover hidden endpoints. Tools like fuzzers can automate this process. Parameter Tampering: Experiment with adding or replacing parameters in requests to access unauthorized data or functionalities.

December 12, 2022 - This is the goal of API penetration testing. There is no single checklist for performing API penetration testing, as the process will vary depending on the specific API and its security vulnerabilities.

September 24, 2025 - Testing techniques include: Sending requests from different IP addresses to evade IP-based rate limits. Modifying API headers and payloads to avoid detection by security controls.

June 4, 2026 - High-profile breaches like T-Mobile (37M records exposed) and Optus (9.8M records leaked) were not caused by advanced exploits: but by simple broken authorization and exposed API logic. Join Medium for free to get updates from this writer.

April 23, 2024 - During testing, a pentester discovers an undocumented parameter that allows adding arbitrary data to customer orders. This could be a vulnerability if the additional data isn’t properly sanitized and validated. Many applications rely on external APIs to function. However, if these APIs are not consumed securely, it can introduce vulnerabilities into your application. This checklist point focuses on identifying weaknesses in your application’s interaction with external APIs.

October 10, 2024 - An API pentesting security checklist serves as a comprehensive guide outlining essential security measures crucial for bolstering the protection of your APIs against potential cyber threats. This checklist is based on established security standards, such as the OWASP API Security Top 10 Risks and BreachLock’s 2023 Penetration Testing Intelligence Report.

How to test: ffuf/gobuster with API wordlists; check JS files (via LinkFinder, JSFScan) for hidden endpoint refs; check Swagger/OpenAPI/GraphQL introspection leaks. ... ffuf -u https://TARGET/FUZZ -w /usr/share/seclists/Discovery/Web-Conten...

Checklist for API Pentesting based on the OWASP API Security Top 10 - 0x48756773/OWASP-API-Checklist

July 8, 2025 - Why it matters: Misconfigured authentication/authorization is the #1 API vulnerability class in 2025. Where the big money hides: Complex logic errors often pay 5× more than XSS. ... Rate Limiting Bypass: Test for missing IP whitelisting or weak rate-limiting algorithms. Example: A crypto exchange allowed unlimited API calls via header spoofing (X-Forwarded-For manipulation).

October 29, 2025 - Server Side Request Forgery - APIs fetching unvalidated remote resources. ... Security Misconfiguration - Exposed endpoints, default settings, or unnecessary services. ... Improper Inventory Management - Unmonitored shadow or zombie APIs.

May 21, 2025 - Some endpoints might not require authentication, or may use predictable tokens (e.g., static API keys or JWTs with no signature validation). Test whether users can access or modify resources beyond their privilege level. For example, can a regular ...

July 16, 2026 - An API penetration test must be exhaustive, covering authentication, authorization, rate limiting, data validation, and business logic flaws. Without a structured checklist, security teams risk missing critical vulnerabilities that attackers ...

February 26, 2026 - If so, maybe you can abuse it. (CAPEC-114) Check if the login process has rate-limiting enabled. If so, test to determine max retry logic to tune before attempting any sort of password brute forcing attack.

This guide is a practical field checklist for authorized testing only. It focuses on method, evidence, communication, and remediation direction so testing improves security posture instead of generating one-off scanner output. Use this sequence for scoped internal assessments, client-approved engagements, and lab simulations. If scope is unclear, everything that follows is noisy. Confirm scope in writing and keep it visible during testing. ... A good API assessment starts with operational readiness, not tooling.