Uncovering Hidden API Vulnerabilities with Fuzz Testing

Since the first modern application programming interfaces (APIs) were developed in the early 2000s by companies like Salesforce, Amazon, and eBay, organizations have grown to heavily rely on them to help fulfill the swelling demand for “connected” software in the modern digital economy. With that said, many APIs contain exploitable vulnerabilities that put businesses at risk of cyberattacks and data breaches. API fuzz testing is one of the best ways to identify and mitigate these vulnerabilities before API deployment.

This blog uncovers the importance of API fuzz testing and highlights its role in developing more secure APIs and software applications.

The Importance of APIs

As Gartner states, APIs “provide the foundation for digital transformation, modernization, and digital business ecosystems.”¹ Simply put, an API serves as a bridge or link between different applications and includes a set of guidelines and procedures that allow applications to communicate and share data, so users can garner all the benefits of those applications.

APIs allow developers to leverage existing functionalities in applications so they don’t have to reinvent the wheel, streamline processes, and enable smoother process integration. Furthermore, they minimize the need for manual data entry, enhance user experiences, and improve employee and business productivity. They also play a vital role in automating routine tasks, speeding up app development and time-to-market, and fostering creativity and innovation. For all these reasons, APIs are considered essential building blocks of the modern-day software development lifecycle (SDLC) and business landscape, which is why securing them is of utmost importance.

What Is Fuzz Testing for APIs and How Does it Work?

Fuzz Testing, or Fuzzing, is a software testing technique used to discover security vulnerabilities and bugs in APIs. Penetration testing is a fuzz testing method used to assess a system’s security, aiming to identify vulnerabilities that could be exploited by attackers. Fuzz testing helps discover unexpected behaviors and vulnerabilities by sending malformed or random data to the target system. This process helps identify how an API behaves under unexpected conditions, revealing potential weaknesses that could be exploited. For example, it analyzes how an API would respond to unusual inputs such as long strings of random characters, special characters, or symbols in the username and password fields. Inputs are generated in the following ways:

• Random Fuzzing: Inputs are generated randomly without any prior or inside knowledge of the input structure.
• Mutation-Based Fuzzing: Valid inputs are taken and modified to create new test cases, introducing variations to real-world inputs.
• Generation-Based Fuzzing: Inputs are generated based on the specifications of the input format, which requires detailed knowledge of the input structure.
• Boundary Value Testing: Inputs are created at the boundaries of allowable input ranges, such as maximum and minimum values.

The Benefits of Fuzz Testing

Fuzz testing is one of the most robust and effective methodologies for API penetration testing and cyberattack prevention – but why?

1. It facilitates comprehensive and early vulnerability detection.

Fuzz testing can uncover vulnerabilities that other testing methods might miss, such as buffer overflows, memory leaks, and unhandled exceptions. It can also catch vulnerabilities during the development phase or early in the SDLC. In doing so, it reduces the risk of security breaches and lowers the cost of remediation.

2. It enhances organizations’ security posture.

Fuzz testing can help organizations significantly improve their overall security by identifying and fixing more vulnerabilities early, even obscure vulnerabilities or vulnerabilities that may not be readily apparent. It can also detect zero-day vulnerabilities to protect applications from unknown bugs and security weaknesses that may result in serious breaches. Furthermore, it maximizes code coverage, allowing for more thorough testing and better testing results with minimal false positives.

3. It supports extensive and scalable testing with minimal manual effort.

Fuzzing tools automate the generation of inputs and testing processes, making it efficient to run extensive tests with minimal manual effort. In this way, they reduce the time and cost of testing, while providing an efficient and scalable means to improve application security and robustness.

4. It allows for continuous, uninterrupted API testing throughout the SDLC.

Roughly 63% of applications have flaws in first-party code, while 70% contain flaws in third-party code. To minimize vulnerabilities and ensure a more secure, better-quality application, testing both first-party and third-party code is critical. Fuzz testing can be automated, allowing for continuous testing of both types of code throughout the SDLC.

Reliable and Effective Fuzz Testing and Robust API Security with BreachLock

BreachLock penetration testing is a fuzz testing method used to assess a system’s security, aiming to identify vulnerabilities that could be exploited by attackers. BreachLock helps discover unexpected behaviors and vulnerabilities by sending malformed or random data to the target system to test how your API behaves under unexpected conditions. Fuzz testing reveals potential weaknesses that could be exploited at any stage of the SDLC and any desired frequency.

Regular and early fuzz testing with BreachLock will enable you to discover unexpected behaviors in APIs and pinpoint security weaknesses that are at high risk of being exploited. Fuzz testing will help to protect your APIs and applications from unauthorized access and misuse, minimizing the probability of data breaches and other cyber incidents. BreachLock’s fuzzing method can be easily combined with other testing methods to reveal a more comprehensive picture of your applications’ security posture.

Learn how BreachLock can help protect your APIs from buffer overflows, unhandled exceptions, cross-site scripting, code injections, and even DoS attacks. Schedule a free discovery call to get started.

About BreachLock

BreachLock is a global leader in Continuous Attack Surface Discovery and Penetration Testing. Continuously discover, prioritize, and mitigate exposures with evidence-backed Attack Surface Management, Penetration Testing, and Red Teaming.

Elevate your defense strategy with an attacker’s view that goes beyond common vulnerabilities and exposures. Each risk we uncover is backed by validated evidence. We test your entire attack surface and help you mitigate your next cyber breach before it occurs.

Know your risk. Contact BreachLock today!

References

1. Gartner Magic Quadrant for API Management