In bug bounty hunting, finding hidden URLs, files, or parameters is essential, but it can feel like searching for a needle in a haystack. FFUF – short for Fuzz Faster U Fool – is a powerful web fuzzer that helps you automate that search. I’ll walk you through how to set up, use, and master FFUF for bug bounty hunting, even if you’re new. Ready? Let’s dive in!
1. Introduction to FFUF 🔍
FFUF is a web fuzzer, specifically designed for web directories and parameters. In simpler terms, FFUF sends a bunch of requests to a target and reports back any that succeed. This tool allows you to automate the process of “fuzzing,” or trying many inputs to reveal hidden files, directories, or parameters on a target website. Once we’ve got the basics covered, I’ll show you some pro tips to help you get the most out of it!
2. Why FFUF is Vital for Bug Bounty 🕶️
Bug bounty hunting often involves testing various endpoints on a web app to reveal vulnerabilities. By automating fuzzing tasks, FFUF lets you find paths other tools might miss. Why is this important? Because many vulnerabilities are hidden behind obscure endpoints that don’t appear in public sitemaps or basic scanning. FFUF can dig out these hidden gems. Whether it’s a secret login page or a hidden API endpoint, FFUF is one of the top tools used by seasoned bug bounty hunters.
3. Setting Up FFUF on Your System 🖥️
Getting FFUF up and running doesn’t require much effort. Here’s a breakdown of the installation process:
Installing Go Language 🛠️
Since FFUF is written in Go, you’ll need Go installed on your system. Follow these steps:
- Install Go: Run
sudo apt install golang-go(for Linux users). - Verify Go: Type
go versionto make sure Go is installed correctly.
Installing FFUF
- With Go installed, you’re ready to install FFUF itself. Type:
go get github.com/ffuf/ffuf - Check Installation: Type
ffuf -h. If you see FFUF’s help menu, you’re set.
4. Basic Commands and First Scans 🏃♂️
Ready to run your first FFUF command? FFUF’s syntax is simple once you get the hang of it.
Basic Directory Fuzzing
The simplest scan you can perform is directory fuzzing:
ffuf -w /path/to/wordlist -u http://target.com/FUZZIn this command:
-wspecifies the path to the wordlist.FUZZtells FFUF to replace this part with words from the wordlist.
5. Directory and File Fuzzing Techniques 🔍
FFUF isn’t just for finding directories; it’s also great for files. Here’s how to tailor your search:
Specific File Extensions
Say you’re hunting for specific file types, like .php or .bak. You can specify these like so:
ffuf -w /path/to/wordlist -u http://target.com/FUZZ.phpContent-Length and Response Filtering 📏
It’s common to get many results, but filtering helps you focus on valuable responses. Use -fs to filter by response size, -fc to filter by status code, or -fr to filter by regex.
6. Advanced FFUF Techniques for Bug Bounty 🚀
Using Multiple Wordlists 🗂️
One powerful feature is multiple wordlists. For instance:
ffuf -w /usr/share/wordlists/list1.txt:/usr/share/wordlists/list2.txt -u http://target.com/FUZZ/FUZZ2Recursive Fuzzing 🔄
By adding -recursion in your command, you tell FFUF to go deeper:
ffuf -w /path/to/wordlist -u http://target.com/FUZZ -recursionBe cautious: Recursive fuzzing can hit a lot of URLs and may be blocked by certain websites if they detect it as abusive.
Fuzzing with POST and JSON Requests 📥
Sometimes, you need to target APIs with POST data or JSON payloads. FFUF supports these with the -X and -d flags:
ffuf -w /path/to/wordlist -u http://target.com/api/endpoint -X POST -d '{"param":"FUZZ"}'7. Optimizing FFUF with Wordlists 📋
FFUF’s effectiveness heavily depends on the quality of the wordlist. Wordlists vary based on the target type:
- Common Wordlists: Try SecLists, a comprehensive collection of fuzzing wordlists.
- Specialized Wordlists: Tailor your lists. An e-commerce site might need terms like “cart,” “checkout,” and “payment.”
8. Interpreting FFUF Outputs 📊
Once you run a command, FFUF displays the responses in this format:
[Status: 200, Size: 1678, Words: 150]Understanding Output Elements:
- Status Code: Indicates the type of response (e.g., 200 for OK).
- Size: The content length.
- Words: Total words in the response.
When hunting, pay attention to Status 200 and unique sizes, as these often indicate something interesting.
9. Common FFUF Errors and Troubleshooting 🛠️
Here’s a quick fix for common FFUF errors:
- Timeouts: Slow servers? Use
-timeout 10to increase wait time. - Too Many 404s: Filter them out with
-fc 404.
Debugging Command Failures 🧰
If FFUF commands aren’t working, try breaking down the command and testing each flag.
10. Best Practices and Pro Tips 🌟
1. Start Small: Test with a small wordlist before moving to larger ones.
2. Experiment with Filters: Adjust filters with -fc, -fs, and -fr for cleaner results.
3. Log Everything: Save your scans. Use -o output.txt to save results.
4. Watch Your Speed: FFUF can overwhelm a site. Lower -rate to avoid being blocked.
5. Combine Tools: Pair FFUF with tools like Burp Suite, Nmap, and Nikto.
11. Using FFUF with Other Bug Bounty Tools 🔧
FFUF integrates well into many bug bounty toolchains:
Combining with Burp Suite
You can export FFUF results to Burp Suite for further analysis. Just use -o results.json.
Pairing with Nmap
Nmap finds open ports, but FFUF helps dig into directories on those open ports.
12. Conclusion and Next Steps 🎉
FFUF is a must-have for bug bounty hunters, helping you find hidden files and directories that could reveal vulnerabilities. Try combining FFUF with other tools for a more comprehensive approach. Don’t stop experimenting and improving your skills with each scan.
FAQs: FFUF for Bug Bounty Hunting
Answer: FFUF, short for “Fuzz Faster U Fool,” is a web fuzzer designed for brute-forcing various web application components. In bug bounty, it helps discover hidden directories, files, and parameters that may contain vulnerabilities.
Answer: Not necessarily! Basic command-line knowledge is helpful, but FFUF itself doesn’t require programming. Understanding how to set up commands and interpret results is sufficient.
Answer: Install Go language first, then run go get github.com/ffuf/ffuf in your terminal. After installation, check by typing ffuf -h to ensure it’s ready.
Answer: SecLists is a popular choice, providing wordlists tailored for various purposes. Choose wordlists based on your target (e.g., general wordlists for directories, tech-specific lists for APIs).
Answer: Yes, some security systems detect brute-forcing attempts. To minimize detection, adjust FFUF’s request rate using the -rate option and use relevant filters to limit unnecessary requests.
Answer: Filtering by status code (e.g., -fc 404) removes results with that status, like 404 (not found) pages. Filtering by size (e.g., -fs 1234) shows only responses matching a specific byte size, helping reduce clutter from unwanted responses.
Answer: Start with smaller wordlists and specific targets before expanding. Also, filter results to avoid irrelevant data, like common error pages. Recursive fuzzing can help, but it’s slower, so only use it when needed.
Answer: No! Only use FFUF on websites you have permission to test, such as bug bounty programs that explicitly authorize fuzzing. Unauthorized use can be illegal and lead to bans.
Answer: Yes, FFUF works well with APIs by fuzzing endpoints and parameters. You can customize requests using headers and JSON data (-H and -d options) to adapt FFUF to different API structures.
Answer: FFUF pairs well with Burp Suite for in-depth analysis, Nmap for port scanning, and tools like Nikto for additional security testing. Combining tools creates a more robust bug-hunting strategy.