ffuf is a fast web fuzzer written in Go, widely used for discovering elements and directories within web applications, making it an invaluable tool for security researchers, penetration testers, and developers interested in web security. This course is designed to guide beginners through the basics of web fuzzing, understanding ffuf, and leveraging its capabilities to identify security vulnerabilities effectively.

Introduction to Web Fuzzing

What is Web Fuzzing?
Web fuzzing is a testing process that involves sending a large number of requests to a web application to discover vulnerabilities, misconfigurations, or hidden resources. It’s an automated approach that can identify issues which would be difficult or time-consuming to find manually.

Importance of Web Fuzzing
Web fuzzing plays a crucial role in web security. It helps uncover potential attack vectors, such as SQL Injection, Cross-Site Scripting (XSS), directory traversal vulnerabilities, and more. Early detection of these issues allows developers to mitigate risks before attackers exploit them.

Getting Started with ffuf

ffuf is easy to install. Since it’s written in Go, you can install it via go get, or by downloading a precompiled binary from its GitHub repository. Here’s how you can install it using go:

go get -u github.com/ffuf/ffuf

Alternatively, for those who prefer using Docker, ffuf is also available as a Docker image.

Basic Usage
The basic syntax of ffuf is as follows:

ffuf -w wordlist -u http://target/FUZZ
  • -w specifies the wordlist file.
  • -u designates the URL to fuzz, with FUZZ as a placeholder where fuzzing happens.

Core Concepts and Usage Scenarios


Wordlists are crucial for fuzzing. They contain the payloads ffuf will use during the fuzzing process. You can use pre-existing wordlists, such as those found in the SecLists repository, or create custom wordlists tailored to your target.

Discovery of Hidden Directories and Files

One of the primary uses of ffuf is discovering hidden directories and files. This is accomplished by fuzzing the URL with different paths:

ffuf -w /path/to/wordlist.txt -u https://example.com/FUZZ

Subdomain Enumeration

ffuf can also be used for subdomain enumeration by fuzzing the domain part of the URL:

ffuf -w subdomains.txt -u https://FUZZ.example.com

This requires a wordlist of potential subdomain names.

Virtual Host Fuzzing (VHOST)

Sometimes, applications serve different content based on the Host header. ffuf can fuzz this header to discover virtual hosts:

ffuf -w vhosts.txt -H "Host: FUZZ.example.com" -u https://example.com

Parameter Fuzzing

ffuf allows for fuzzing of GET and POST parameters to uncover potential vulnerabilities:

  • GET parameter fuzzing:
ffuf -w params.txt -u https://example.com/page?param=FUZZ
  • POST parameter fuzzing:
ffuf -w params.txt -X POST -d "param=FUZZ" -u https://example.com/page

Rate Limiting and Filtering

ffuf provides options to control the rate of requests (-p, -rate) and to filter or match HTTP responses based on status codes, sizes, or words (-fc, -fs, -fw).

Advanced Features


For in-depth directory traversal, ffuf supports recursion with the -recursion flag, allowing the tool to follow directories discovered during fuzzing.

Scripting and Automation

ffuf can be integrated into scripts and automation workflows, enabling automated fuzzing tasks and the incorporation of fuzzing into CI/CD pipelines for security testing.

Output Handling

Results from ffuf can be output in various formats (CSV, JSON, etc.) for further analysis or reporting purposes.

Best Practices and Ethical Considerations

While ffuf is a powerful tool, it’s important to use it ethically and legally. Always have permission before testing a target, and consider the impact of your fuzzing on the target’s resources. Responsible disclosure is key when vulnerabilities are found.


ffuf is a versatile and efficient tool for web fuzzing, capable of uncovering a wide range of vulnerabilities and hidden resources. Through understanding its core functionalities, options, and ethical use, you can greatly enhance your web security testing efforts. Remember, continuous learning and practice are essential to mastering web fuzzing with ffuf.

This course provides a foundation in ffuf and web fuzzing. With practice and further study, you can develop deeper expertise in web security testing and contribute to building safer, more secure web applications.

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