What Is API Security Testing?


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API security testing has become an essential part of the modern web application development system in recent years. The only application of REST is on top of the hypertext transfer protocol that powers the web. It indicates that exposed RESTAPI offers similar to traditional websites and applications while being more challenging for being tested with automated web security scanners.

What is a REST API?

Before discussing the challenges of effective security testing of RESTAPI, it should be clarified what we are talking about. An API is a mechanism of conveying information between two computer systems. An API security testing tool could be achieved either at the code level on at the network level depending on whether the two systems are running on the same machine. An API almost always refers to an interface across the web in a commercial context that is the most common way of connecting disparate computer systems.

Modern Web API is implemented using represent relational state transfer. REST is an architectural style in which all of the information required for accessing or changing the state of a web service could be made in a single API call, such as obtaining a data record or updating a database.

A RESTful API offers a clean separation of concerns between the front end and the back end.

The RESTful style has been recognized as the international standard. It could be consumed simultaneously by mobile devices, web applications, and IoT devices without any alterations that make it the cheapest and most flexible way for building modern applications.

Principles RESTful API security testing

There are four core principles for API security testing tools. As is often the case, however, these principles could be difficult to put into practice.

Simple principles are as follows and could be implemented trivially into a web server:

It would help if you rejected inputs of an incorrect type

Input data null or empty should be rejected when null is unacceptable.

It would help if you rejected inputs of an incorrect size

More difficult principals need an intimate understanding of the range of acceptable values and users that could be hard for informing without understanding how a RESTAPI should be consumed.

For a given input value, the RESTAPI must provide the expected output

It could be easy to test when the input domain and the output range as simple as it will become extremely difficult while building RESTful permission API to enable users to submit their content.

It would help if you rejected input values that are outside the expected domain

It will be easy when the domain is simple but will become more complicated when users could supply content.

The API must provide only the data they are authorized to access for a given user

Is formations at the fine and resources scaled by the permission level, this could be easy for implementation. Nevertheless, authorization is a hard problem with many multi-billion dollar companies around for solving it.

API security tests

The security audit system developed to ensure an API against external attacks consists of three major checking forms.

Security testing

Protection tests verify the fulfillment of fundamental compliance criteria. The following questions are included:

  1. What type of authentication is required for the API, that is, how do you determine an end-identity? user’s
  2. What kind of encryption is applied to the stored data, and at which points are the transfer decrypted?
  3. What are the terms by which users will access resources?

The first step in the audit process is to avoid big vulnerabilities.

Penetration testing

Penetration testing allows you to harden the application’s exterior surface against bugs that may have crept in during development. In this stage, external facets of the API in a managed environment are deliberately targeted. It can be carried out with automatic software like Netspark or Acunetix.

The following precautions should be taken before planning a penetration test:

  • Identify a list of possible application vulnerabilities (e.g., has tooled such as photos that can expose a traversal attack directory);
  • Order the products according to your risk.

Fuzz Testing

The final component of a security audit procedure in which an API is moved to its limits is fuel efficiency monitoring. It can be achieved by submitting large numbers of requests to it, which try to vary the data with the greatest possible creativity to cover the potential of high-volume bugs that could undermine the protection.

How to perform a security test on an API?

A public API for testing involves requests to an endpoint of the program being assessed using client applications. Almost always, this is an HTTP client, and there are a lot of free options. The most popular clients are Postman or Insomnia. 

Sleeplessness is the perfect way for smaller APIs because it is simple to handle and needs little setup. For more advanced APIs, Postman is best because it stores authentication parameters and allows you to generate query sets. Postman also offers the ability, if the applications are continuously evolving, to automate monitoring by “monitors.”

Step 1: Find safety requirements. 

Step 2: You must first consider the general specifications to schedule a security test on an API. This involves asking: 

  • Can the API and accessible via HTTPS using the TLS/SSL certificate?
  • What are authorization classes available in the framework for various resources?
  • What is the flow of authentication? Is an outside supplier used for OAUTH?
  • What is the API’s attack surface? How may a hostile individual subvert the request?
  • You must know what constitutes a passing vs. failing of the exam to answer the above questions.

Step 3: Provide a test environment. It is time to plan an application environment for testing until the scope of the test is established. The standard staging environment can be used for smaller applications. It is easier to create a different framework to test bigger programs with plenty of internal states — either by replicating all the resources in the scanning environment or using tools like WireMock to mock them.

Step 4: Search your API for health. To ensure that it is properly configured, send some requests to the API.

Step 5: Specify the domain of input. It is necessary to consider what each parameter is doing and the variations that each parameter can be before creating individual test cases. It allows you to set edge cases (hardly valid values) and identify the most sensitive parameters to injection attacks (like SQL injections).

Step 6: Develop test cases and run them. You can build and perform experiments, compare the real performance with the predicted output after preparing the test environment, and understand potential edge cases. As an example, depending on the type of test being performed, you can group these accordingly.

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