API pentesting

Test your applications, methods and systems for vulnerabilities using our API pen testing. NFIR offers professional API pentesting services, which can help you secure your applications from outside attacks that attempt to manipulate them, causing breaches in the confidentiality of your network.

Scope examples

During an API pen test, the API can be tested from different perspectives: unauthorized (Black Box) or authorized (Grey Box).

What attack scenarios are possible for API pen testing?

The most common attack scenario for an API is a combination of a Black and Grey Box. An illustrative example is provided below for both attack scenarios. During an intake, the requirements will be mapped out in order to then choose a suitable scenario together with the client.

Black box pen testing hacker organization applications security information

Black Box of the API

With minimal information, a picture will be formed of vulnerabilities in the API. The possibility of using API requests without sending along the required authentication will also be explored. Through open source research (OSINT), as much information as possible will be collected to discover potential vulnerabilities based on this information.

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Grey Box of the API

Testing the API from an authorized perspective is at least as important as from an unauthorized environment. This scenario mimics the actions of a malicious hacker should they gain access to a valid API token. This is accomplished, for example, by conducting a phishing attack or a social engineering attack. Questions that can be answered with this are for example: What vulnerabilities are present and is it possible to request more information than intended or send API requests that do not belong to the token's rights profile?


NFIR uses the OWASP Web Security Testing Guide (WSTG) and the OWASP API Security Top 10 for pen testing APIs. These standards give you the guarantee that the pen test will be carried out according to the correct standards and completely. We find it important to be as transparent as possible about the execution of the pen test. For this reason, we offer a checklist for various pen testing standards which is added to the report. This allows you to see which checks have been carried out, which could not be carried out and which, if any, were not applicable.

Sample API Pen Testing Report

Sample API Pen Testing Report

A sample report (NL/EN) of an internal black box pen test is available. In this report, a pen test was performed on a fictitious environment, revealing vulnerabilities.


Which systems can you have tested by NFIR's experts?

Which systems can you have tested by NFIR’s experts? Our ethical hackers check the technical resilience of (web) applications, websites, IT and OT infrastructures, API links and mobile apps. If you have a different environment that you would like to have controlled, we will be happy to discuss it with you.