4 Best Practices For Fuzz Testing

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July 16, 2021 Programming

Software testing can help companies identify flaws in their software early on and make necessary corrections. In addition, software testing can also help companies find bugs and errors to further enhance system accuracy and reliability.

One of the most popular software testing techniques used today is called fuzz testing. There are many resources online that discuss how to conduct fuzz testing techniques for your software. It’s important to check this out before you can implement it in your current software development system. Meanwhile, this article will also give you some helpful insights about fuzz testing and some of the best practices to optimize this process.

What Is Fuzz Testing And Why Is It Important?

Fuzz testing is a beneficial testing strategy, which both novice and advanced programmers alike can use. It is an automated, real-time software testing method that entails providing random, invalid, or error-prone information as inputs to a program. The software is then monitored continuously for potential errors including crashes, improper built-in code statements, or possible memory leaks. This testing has become quite popular due to its ability to uncover bugs and errors that are difficult to find and fix.

Fuzz testing is also a form of security testing that locates security flaws and code errors in networks, operating systems, or software. Fuzz testing is performed using a buzzer, a small program that automatically injects random data into a non-critical code area and finds bugs. In a way, random or unexpected inputs are injected into the system, likewise resulting in unexpected results.

To understand how this works, you will first need to understand what happens when security testers perform the actual testing. A tester writes program codes susceptible to security holes, and then uses a buzzer to generate fake test cases. The tester then parses the generated test cases to identify inputs that can be used to improve the system.

What Are The Best Fuzz Testing Practices?

With greater demands for more accurate software testing, fuzz testing has become more popular among software engineers. This software testing technology allows for a greater degree of flexibility in finding bugs instead of invalidating the entire testing process. Some of the benefits of fuzz testing include running the test cases while the application is not open for use, which can significantly cut down the debugging time.

To fully experience the benefits of fuzz testing, you need to ensure that you follow the best practices for this method. Here are some ways to ensure that the fuzz testing is done efficiently:

1. Follow The Fuzz Testing Phases

There are six fuzz testing phases you need to follow strictly to ensure the efficiency of your software and security testing:

Determine The Target System – The target system is the software to be developed. The targeted component of the system can be reached through different interfaces and protocols.
Identify Your Inputs – Once the target system has been identified, the interface where input data is inserted and the corresponding inputs are also created for testing.
Generate Your Fuzz Data – Random and unexpected invalid values are inserted and fuzzed.
Execute The Test Using Your Generated Fuzz Data – The fuzzed data is used to test the application.
Monitor System Behavior – The behavior of the system is monitored for potential security vulnerabilities, crashes, and memory leaks.
Check Log Defects – If there are any defects on the application, these are checked and logged accordingly to address them before the product’s release.

It’s essential to follow these phases and never miss a step so you can check any flaws in the application thoroughly.

2. Learn The Fuzz Testing Strategies

There are two fuzz algorithm strategies you can use:

Mutation or Dumb Fuzz Testing – In this strategy, the fuzz testing engine has no information on the structure of the input it’s creating. Mutation strategies create tests by appending and flipping additional data on the system.
Generation or Intelligent Fuzz Testing – In this strategy, the fuzz testing engine understands the inputs and the interface of the application. This strategy creates tests following the state model and the input structure of the software to allow deeper code coverage.

The mutation strategy is easier to perform than the generation-based strategy because it doesn’t require a complete understanding of the software’s protocol. However, the generation-based approach is more efficient because it has valid input combinations and provides better code coverage and code paths. Although the generation strategy takes longer to complete, it’s considered a more thorough process for fuzz testing.

3. Combine Behavioral And Coverage-Guided Fuzz Testing

There are two types of fuzz testing, and it’s more efficient when you combine these two:

Behavioral or Traditional Fuzz Testing – This technique uses inputs to determine the effectiveness of its implementation under test and allows the tester to make mutations that are very close to valid. This technique also helps the tester observe how the implementation’s behavior under test shifts to different decisions for the following fuzz tests.
Coverage-Guided Fuzz Testing – This technique uses contextual information from a source code to create inputs for the fuzz tests and correlate the results of any system crash. Using this technique improves the cycle time and provides an update on vulnerable areas. The benefit of this technique is that it can be done without completing the development of the software, since it can be accomplished even with small parts of the app.

The benefit of combining these techniques for efficient fuzz testing is to help the tester fully understand why the app has bugs or why it’s crashing. This also allows the testers to generate new test cases to reach the other parts of the software’s code. Aside from that, combining these techniques will help the testers determine the specific features of the app that needs fixing.

4. Choose The Right Fuzz Testing Tools

Testers must be comfortable with the fuzz testing tools they use. The best fuzzing tools can generate data that are not so different from the expected input of the application to avoid being rejected by the software. They should also be able to provide data or inputs with better chances of being accepted by the program. These unexpected inputs will trigger certain behaviors in the application so the tester can identify if there are errors or security breaches.

Final Thoughts

In many software development methods like agile methods, software testing is a critical phase. Fuzz Testing is a well-known quality assurance testing performed to uncover security vulnerabilities and coding errors in the software, networking, or OS platforms. This technique can be used in software testing, system testing, database verification, performance testing, and web testing.

To improve the efficiency of fuzz testing, testers must follow its phases and be aware of its different testing strategies. Aside from that, testers should also use and combine other techniques to ensure better code coverage. Lastly, choosing the right fuzz testing tool is critical as these should help the tester determine unexpected inputs to identify gaps in the system.