Subscribe to our Blog

Get the Latest Application Security News and Content

What Is a Fuzzer and What Does Fuzzing Mean

Fuzzing is the art of automatic bug detection,  used for assessing the security and stability of applications and software. A Fuzzer sends invalid, unexpected, random data to the targeted application’s input points in order to stress the application to cause unexpected behavior, resource leaks, or even a crash.

Why Should you Fuzz Your Applications?

The dramatic increase in high profile cyber attacks over the last few years, many of which resulting in substantial financial and reputational losses, as well as record fines, highlights that not enough is being done and/or current cybersecurity methods are ineffective.

Fuzz testing is used to discover the vulnerabilities in software applications performed prior to the application’s production release, with the purpose of ensuring the quality of the application’s runtime behavior in unassumed scenarios, so it’s a way of enhancing the security posture of your application.

3 Key Factors For Success in Fuzzing

1. Speed

Easy integration and fast scanning enable the fuzzer to keep up with the pace of the SDLC.
If a fuzzer can run concurrent scans, vulnerabilities can be detected even faster.

2. Coverage

Coverage describes how much of the application’s code can be exercised by a fuzzer.
The amount of coverage that a fuzzing solution provides is measured by lines of application code, code branches, or code paths.

3. Reporting

Identified vulnerabilities require in-depth analysis into the specific context of the manifested bug. The Fuzzer should report all related risk factors without any false positives, as well as the severity of the impact,  allowing developers to prioritise and remediate vulnerabilities.

So, How Does Fuzzing Work?

  1. Generating test cases

    Each security test case can be generated as a random, or semi-random data set, sent as input to the application, either generated in conformance to the format requirements of the system’s input, or as completely malformed chunks of data that the system was not meant to understand or process.
    What do you think would happen to an application if negative numbers, null characters, or even special characters for example, were sent to some of the input fields? 
    How would your application behave?

  2. Interfacing with the target to deliver the input

    A fuzzer can interface with an application, a protocol, or a file format by sending the test case to the target over a network or via a command-line argument of a running application. Imaginative use cases in these situations can reveal ways to expose the relevant piece of code with the right specific data.

  3. Monitoring the system to detect crashes

    The success of a fuzzing scan is measured by the ability to confirm the impact that a fuzzer makes on the targeted application. 
    This can be determined by using a debugger to see the crash traces or by adding timeouts that will expose the application’s runtime misbehavior.
    Do you know how your production application behaves when given completely unexpected data as input?

Find unknown vulnerabilities using NexFuzz and ensure that unforeseen events of malicious intent do not affect the posture of your business.

NexFuzz is the world’s first AI-powered Application Security Fuzzing Tool!

NeuraLegion’s NexFuzz is a self-evolving, adaptive-learning fuzzing solution that applies evolution strategies and reinforcement learning to extensively analyze the response of the application and the context of a given attack surface, breaking the assumed scope of the target and reporting vulnerabilities that are invisible to other, unintelligent fuzzing tools!

As the new generation of AI-powered Application Security Testing (AIAST), NexFuzz’s easy to use and highly scalable SaaS solution combines different technologies to raise efficiency and performance as the most comprehensive, reliable,  and accurate solution, with zero false positives.

Get the Latest Application Security News and Content


Scale up efforts and set the new standard of integrating security into modern development!