Software is a sum of data and instructions controlling the functions of a computer. It determines how the hardware performs computer instructions. On the other hand, software testing is the evaluation and verification of the software’s performance.

A computer popup box screen warning of a system being hacked, compromised software environment. 3D illustration.

Fuzz testing has been around for decades, but little is known about it. If you want to understand a bit more, this article will give you a comprehensive guide.

Importance of Software Testing

Software testing is said to be the checks done to ensure software packages and applications are as effective as they’re designed to be. One of the major advantages of software testing are:

  • Performance enhancement
  • Cost reduction
  • Error identification
  • Bug prevention

Fuzz Testing

Fuzz testing is a technique in software quality assurance, which is used to check program design and security shortcomings. Fuzzing can also be used for networks and operating systems to expose loopholes and security vulnerabilities. For your application security, fuzzing is such a good point to start.

How Fuzzing Works

When fuzz testing, technicians input volumes of data randomly into software programs. They aim to get the software to crash, so they can troubleshoot any vulnerabilities. When they identify a problem, they often use special software called a fuzzer to fix any possible causes.

woman finding computer getting virus attack

Fuzzers work by exposing the software to weak links that might be exploited by programs used for hacking. These include Structured Query Language (SQL) injection, Disk Operating System (DOS), buffer overflow, and cross-site scripting. Because fuzz testing relies on threats causing software crashes, it may be less effective for handling security threats like spyware, trojans, viruses, worms, and keyloggers.

Fuzz testing may seem simplistic and easy, but it protects programs by revealing defects often overlooked during software development. It gives an overview of the quality of a program. When shortcomings are exposed, improvements are made to prevent them.

The Fuzzing Process

Fuzzers send defective inputs to selected software, and this gets the program to malfunction and possibly crash. When the glitch happens, the underlying problem is identified and fixed. However, fuzz testing has been said to be more effective if used with other debugging programs.

Types of Fuzzers

Fuzzers can generally be categorized into mutation-based, generation, and evolutionary. Here are their specifications:

  • Mutation-based Fuzzing

Mutation-based fuzzers are the easier ones to create. They randomly mutate inputs to create abnormalities, which poke at a program to get it to crash. Some mutation fuzzers will select valid inputs, which they’ll modify to aggravate a program.

  • Generation Fuzzing

As opposed to mutating existing ones, generation-based fuzzers create inputs from naught. They use available data based on the targeted programs to come up with samples. Some generation fuzzers will break file formats and create inputs they’ll randomly fuzz.

  • Evolutionary Fuzzing

Evolutionary fuzzing is an advanced technique in which the fuzzer will use feedback from each fuzz to create a targeted input format. It usually relies on other techniques to get useful feedback.

  • Methods of Fuzzing

Fuzz testing was developed in 1989 by Barton Miller. Over the years, it has evolved to cater to different needs and software enhancements. The different types of fuzzing that resulted in changing technological climate include:

  • Random fuzzing -This is a random method of inputs toward a targeted software. It’s been likened to a monkey typing on a keyboard.
  • Template fuzzing – This is also referred to as grammar fuzzing. It relies on a template that’s manually created based on the targeted software’s architecture.
  • Guided fuzzing -Inputs are based on the behavior of the targeted software. The fuzzer will learn from the system’s response after each input is generated. This allows it to target specific areas for analysis.

Overall, no fuzzing method can be said to be better than the others because each address specific types of bugs.

What Is Fuzzing Used For?

Hackers succeed by carefully studying a program until they find its weaknesses. They target those deficiencies to manipulate the systems.

Similarly, fuzzing is used for pushing the bounds of a system to identify any possible software bugs. Because fuzzing can pinpoint weaknesses, it can be used by hackers looking for areas to exploit and system defenders looking for areas to fortify.

For effective functionality, a fuzzer has to do the following:

  • Generate test cases
  • Record the test cases
  • Poke the target program or software to get it to crash
  • Detect any crashes

Pros and Cons of Fuzzing

Fuzzing has its advantages, but it’s not a one-shot-one-kill method of managing system threats. The following identifies some of the pros and cons of fuzzing.


  1. It’s Effortless 

With little effort, fuzzing can give you desired results. Once you set up your fuzzer, you can leave it to run in the background with no interference or need for constant monitoring. It can run for hours, days, or months, depending on what you need.

  1. It’s Automated

Fuzzing is often an automated process; therefore, it can expose bugs you may have missed in a manual audit.

  1. It Provides Quality Control

Fuzzing pokes at a software program, potentially pushing it to its limits and exposing areas that need improvement.


1. It May Not Find All the Bugs

The fuzzing methods commonly used are effective, but they may fail to expose all the bugs in a program. Bugs not causing a crash will go undetected by fuzzers. Malicious bugs like spyware, viruses, and keyloggers are serious threats that can go undetected.

  1. It Doesn’t Analyze All Crashes

Some crashes can be difficult to analyze, especially if there’s limited knowledge of the software’s internal design. This means fuzzers may require supporting software to be fully effective.

In A Nutshell

Fuzzing is a tried and tested technique for the detection of software defects. It assists with strengthening programs and it ultimately saves organizations time and resources.

Fuzzing can also be said to be one of the easiest ways of exposing system weakness. Although it’s not common, there’s a steady increase in the demand for it. If you’d like to find ways to strengthen your system, why not give fuzzing a shot? You won’t regret it.