Fuzzing (The Dynamic Software Testing Method) and Fuzzers the Caterpillar

TL;DR: Fuzzing is an automated dynamic software testing method that improves software security and reliability by feeding programs a wide range of random or unexpected inputs to detect crashes, errors, and vulnerabilities, including zero-day exploits. It is cost-effective, efficient, and particularly adept at uncovering issues like SQL injection and cross-site scripting attacks, enabling developers to identify and fix bugs early in the development process for better, more secure software.

Fuzzers, the caterpillar

If I were to start this article by asking if you’re familiar with fuzzing, would you think of a fuzzy, little caterpillar or something AppSec related? (Since I'm the one writing this, it’s likely both...)

Fuzzing, or fuzz testing, is a dynamic software testing method (automated) that helps to uncover potential bugs and security vulnerabilities. It’s a valuable tool for improving the security and reliability of our software systems. Its main function is to feed a program with random, invalid, or unexpected data as input that could be missed by traditional testing in an attempt to crash a system or trigger errors. The problem is that malicious hackers use this technique as well to find vulnerabilities in our software.

If you’re so inclined, you can learn more about the history of fuzzing on Wikipedia or more about fuzzing at OWASP.

How do fuzzers work? It’s pretty simple, in theory.

1. They generate a wide variety of inputs, from random data to valid inputs

2. These are fed into the system

3. The fuzzer monitors crashes, errors, and unexpected outputs for signs of vulnerabilities.

If anything crashes or issues arise, the fuzzer can help analyze which input triggered the crash or issue, zeroing in on the potential vulnerability in the source code.

So why is fuzzing so important, and what are the benefits?

• It’s super effective at finding vulnerabilities that you might miss during regular testing. This includes zero-day exploits.

• Through fuzzing, you find more vulnerabilities, have a chance to fix them, and improve your software's security.

• Fixing bugs early in development is more cost-effective than resolving them later or after deployment.

• Fuzzing has low overhead in terms of cost and time, so it’s worthwhile to invest in it to help detect zero-day exploits and vulnerabilities.

• Most effective at uncovering vulnerabilities by SQL injection and cross-site scripting attacks.

• Fully automated! Super efficient! Low effort!

Hopefully, you’ve learned something new today about fuzzing! Thank you for reading!