Akamai acquired Noname Security in June 2024. This archived blog post was originally published on July 12, 2023.

If your job is to develop or protect APIs, you’ve likely seen firsthand that testing APIs for security gaps ensures a range of benefits to the business and its customers alike, including:

• Keeping the APIs functioning reliably and securely, and performing as expected under different circumstances 

• Helping to identify API issues such as incorrect data formats, missing or inaccurate data, and faults in authentication or authorization 

• Minimizing downtime, reducing the risk of errors, and improving the overall quality of the software system

It’s important to note that properly testing your APIs in development — early, frequently, and comprehensively — can help prevent your organization from experiencing an API attack that places your data, customers, and ability to operate at significant risk. 

Many organizations use an approach called fuzzing to assess an API’s security. 

In this blog post, we’ll spend some time exploring what fuzzing is, the limitations it presents, and the importance of having a strategy and a solution that are designed to find and address the common API vulnerabilities that today’s attackers frequently exploit.

We’ll also touch on some useful resources to help you test your APIs early and often.

Fuzzing is a technique used in software testing to identify potential vulnerabilities or bugs in a program by inputting random or unexpected data into it. 

The aim of fuzzing is to cause the program to crash or behave surprisingly, which can be an indication of a security weakness or programming error. The use of fuzzing can help identify issues that may not be apparent through traditional testing methods, such as unit testing or manual testing. 

Fuzzing can be performed manually or automatically by using specialized tools, and it can be tailored to specific applications or APIs. The results of fuzzing can provide insights into the robustness and reliability of a software program, and can be used to improve its overall security and performance.

Although fuzzing can be a useful method for identifying security weaknesses, it has its own limitations. These include the fact that fuzzing can only test for known vulnerabilities and cannot detect unknown vulnerabilities. For example, it may not be able to identify vulnerabilities in complex systems or those that require a specific sequence of events to trigger. 

Fuzzing can also be limited by the quality of the input data used in the testing process. It’s important to acknowledge that fuzzing can be time-consuming and resource-intensive. 

So, although fuzzing can be helpful, its limitations mean that organizations should only use it in conjunction with other security-focused testing techniques and tools — if at all.

By conducting thorough API testing, developers can ensure that their software applications perform optimally and deliver a secure and seamless user experience. 

Without proper testing, a minor error in the API could have major downstream effects on the functionality of the entire application. By implementing a comprehensive API testing strategy, developers can ensure that everything is working as intended before the API is released to the end user. This can save time and resources, while also improving the overall quality of the application.

Business logic is the underlying logic or rules that govern the behavior of a system or application. It defines the expected behavior of an application, which is based on a set of rules, algorithms, and workflows. 

Business logic ensures that the application operates as intended and produces the expected results. Testing your business logic is mandatory if you truly want to unearth potential vulnerabilities. Only feeding random input data to an application to detect vulnerabilities via fuzzing just won’t cut it.

Although fuzzing can be a useful method for identifying security vulnerabilities, it is not effective in detecting issues related to the application’s business logic. This is because fuzzing does not consider the expected behavior of the application, but instead focuses on identifying weaknesses in the input validation process.

Testing APIs in development can help you reduce risk and avoid the costs of fixing coding errors and misconfigurations. Here are some core capabilities to look for and incorporate into your processes.

• Running a wide range of automated tests that simulate malicious traffic

• Discovering vulnerabilities before APIs enter production, reducing the risk of successful attacks

• Inspecting your API specifications against established governance policies and rules

• Performing API-focused security tests that run on demand or as part of a CI/CD pipeline

Comprehensive API security testing is a critical step in the API development process, guaranteeing that an API functions securely and as expected. It is essential to conduct this testing phase to ensure that the API is reliable, stable, and performs optimally throughout its lifespan. 

Failure to perform thorough API testing may result in the emergence of errors and defects, which may compromise the security and reliability of your APIs.