ffuf-web-fuzzing

# FFUF (Fuzz Faster U Fool) Skill > **Contributed by:** [Joseph Thacker (@rez0)](https://twitter.com/rez0__) ## Overview FFUF is a fast web fuzzer written in Go, designed for discovering hidden content, directories, files, subdomains, and testing for vulnerabilities during penetration testing. It's significantly faster than traditional tools like dirb or dirbuster. ## Installation ```bash # Using Go go install github.com/ffuf/ffuf/v2@latest # Using Homebrew (macOS) brew install ffuf # Binary download # Download from: https://github.com/ffuf/ffuf/releases/latest ``` ## Core Concepts ### The FUZZ Keyword The `FUZZ` keyword is used as a placeholder that gets replaced with entries from your wordlist. You can place it anywhere: - URLs: `https://target.com/FUZZ` - Headers: `-H "Host: FUZZ"` - POST data: `-d "username=admin&password=FUZZ"` - Multiple locations with custom keywords: `-w wordlist.txt:CUSTOM` then use `CUSTOM` instead of `FUZZ` ### Multi-wordlist Modes - **clusterbomb**: Tests all combinations (default) - cartesian product - **pitchfork**: Iterates through wordlists in parallel (1-to-1 matching) - **sniper**: Tests one position at a time (for multiple FUZZ positions) ## Common Use Cases ### 1. Directory and File Discovery ```bash # Basic directory fuzzing ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ # With file extensions ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -e .php,.html,.txt,.pdf # Colored and verbose output ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -c -v # With recursion (finds nested directories) ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -recursion -recursion-depth 2 ``` ### 2. Subdomain Enumeration ```bash # Virtual host discovery ffuf -w /path/to/subdomains.txt -u https://target.com -H "Host: FUZZ.target.com" -fs 4242 # Note: -fs 4242 filters out responses of size 4242 (adjust based on default response size) ``` ### 3. Parameter Fuzzing ```bash # GET parameter names ffuf -w /path/to/params.txt -u https://target.com/script.php?FUZZ=test_value -fs 4242 # GET parameter values ffuf -w /path/to/values.txt -u https://target.com/script.php?id=FUZZ -fc 401 # Multiple parameters ffuf -w params.txt:PARAM -w values.txt:VAL -u https://target.com/?PARAM=VAL -mode clusterbomb ``` ### 4. POST Data Fuzzing ```bash # Basic POST fuzzing ffuf -w /path/to/passwords.txt -X POST -d "username=admin&password=FUZZ" -u https://target.com/login.php -fc 401 # JSON POST data ffuf -w entries.txt -u https://target.com/api -X POST -H "Content-Type: application/json" -d '{"name": "FUZZ", "key": "value"}' -fr "error" # Fuzzing multiple POST fields ffuf -w users.txt:USER -w passes.txt:PASS -X POST -d "username=USER&password=PASS" -u https://target.com/login -mode pitchfork ``` ### 5. Header Fuzzing ```bash # Custom headers ffuf -w /path/to/wordlist.txt -u https://target.com -H "X-Custom-Header: FUZZ" # Multiple headers ffuf -w /path/to/wordlist.txt -u https://target.com -H "User-Agent: FUZZ" -H "X-Forwarded-For: 127.0.0.1" ``` ## Filtering and Matching ### Matchers (Include Results) - `-mc`: Match status codes (default: 200-299,301,302,307,401,403,405,500) - `-ml`: Match line count - `-mr`: Match regex - `-ms`: Match response size - `-mt`: Match response time (e.g., `>100` or `<100` milliseconds) - `-mw`: Match word count ### Filters (Exclude Results) - `-fc`: Filter status codes (e.g., `-fc 404,403,401`) - `-fl`: Filter line count - `-fr`: Filter regex (e.g., `-fr "error"`) - `-fs`: Filter response size (e.g., `-fs 42,4242`) - `-ft`: Filter response time - `-fw`: Filter word count ### Auto-Calibration (USE BY DEFAULT!) **CRITICAL:** Always use `-ac` unless you have a specific reason not to. This is especially important when having Claude analyze results, as it dramatically reduces noise and false positives. ```bash # Auto-calibration - ALWAYS USE THIS ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -ac # Per-host auto-calibration (useful for multiple hosts) ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -ach # Custom auto-calibration string (for specific patterns) ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -acc "404NotFound" ``` **Why `-ac` is essential:** - Automatically detects and filters repetitive false positive responses - Removes noise from dynamic websites with random content - Makes results analysis much easier for both humans and Claude - Prevents thousands of identical 404/403 responses from cluttering output - Adapts to the target's specific behavior **When Claude analyzes your ffuf results, `-ac` is MANDATORY** - without it, Claude will waste time sifting through thousands of false positives instead of finding the interesting anomalies. ## Rate Limiting and Timing ### Rate Control ```bash # Limit to 2 requests per second (stealth mode) ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -rate 2 # Add delay between requests (0.1 to 2 seconds random) ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -p 0.1-2.0 # Set number of concurrent threads (default: 40) ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -t 10 ``` ### Time Limits ```bash # Maximum total execution time (60 seconds) ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -maxtime 60 # Maximum time per job (useful with recursion) ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -maxtime-job 60 -recursion ``` ## Output Options ### Output Formats ```bash # JSON output ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -o results.json # HTML output ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -of html -o results.html # CSV output ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -of csv -o results.csv # All formats ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -of all -o results # Silent mode (no progress, only results) ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -s # Pipe to file with tee ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -s | tee results.txt ``` ## Advanced Techniques ### Using Raw HTTP Requests (Critical for Authenticated Fuzzing) This is one of the most powerful features of ffuf, especially for authenticated requests with complex headers, cookies, or tokens. **Workflow:** 1. Capture a full authenticated request (from Burp Suite, browser DevTools, etc.) 2. Save it to a file (e.g., `req.txt`) 3. Replace the value you want to fuzz with the `FUZZ` keyword 4. Use the `--request` flag ```bash # From a file containing raw HTTP request ffuf --request req.txt -w /path/to/wordlist.txt -ac ``` **Example req.txt file:** ```http POST /api/v1/users/FUZZ HTTP/1.1 Host: target.com User-Agent: Mozilla/5.0 Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9... Cookie: session=abc123xyz; csrftoken=def456 Content-Type: application/json Content-Length: 27 {"action":"view","id":"1"} ``` **Use Cases:** - Fuzzing authenticated endpoints with complex auth headers - Testing API endpoints with JWT tokens - Fuzzing with CSRF tokens, session cookies, and custom headers - Testing endpoints that require specific User-Agents or Accept headers - POST/PUT/DELETE requests with authentication **Pro Tips:** - You can place FUZZ in multiple locations: URL path, headers, body - Use `-request-proto https` if needed (default is https) - Always use `-ac` to filter out authenticated "not found" or error responses - Great for IDOR testing: fuzz user IDs, document IDs, etc. in authenticated contexts ```bash # Common authenticated fuzzing patterns ffuf --request req.txt -w user_ids.txt -ac -mc 200 -o results.json # With multiple FUZZ positions using custom keywords ffuf --request req.txt -w endpoints.txt:ENDPOINT -w ids.txt:ID -mode pitchfork -ac ``` ### Proxy Usage ```bash # HTTP proxy (useful for Burp Suite) ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -x http://127.0.0.1:8080 # SOCKS5 proxy ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -x socks5://127.0.0.1:1080 # Replay matched requests through proxy ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -replay-proxy http://127.0.0.1:8080 ``` ### Cookie and Authentication ```bash # Using cookies ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -b "sessionid=abc123; token=xyz789" # Client certificate authentication ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -cc client.crt -ck client.key ``` ### Encoding ```bash # URL encoding ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -enc 'FUZZ:urlencode' # Multiple encodings ffuf -w /path/to/wordlist.txt -u https://target.com/FUZZ -enc 'FUZZ:urlencode b64encode' ``` ### Testing for Vulnerabilities ```bash # SQL injection testing ffuf -w sqli_payloads.txt -u https://target.com/page.php?id=FUZZ -fs 1234 # XSS testing ffuf -w xss_payloads.txt -u https://target.com/search?q=FUZZ -mr "<script>" # Command injection ffuf -w cmdi_payloads.txt -u https://target.com/execute?cmd=FUZZ -fr "error" ``` ### Batch Processing Multiple Targets ```bash # Process multiple URLs cat targets.txt | xargs -I@ sh -c 'ffuf -w wordlist.txt -u @/FUZZ -ac' # Loop through multiple targets with results for url in $(cat targets.txt); do ffuf -w wordlist.txt -u $url/FUZZ -ac -o "results_$(echo $url | md5sum | cut -d' ' -f1).json" done ``` ## Best Practices ### 1. ALWAYS Use Auto-Calibration Use `-ac` by default for every scan. This is non-negotiable for productive pentesting: ```bash ffuf -w wordlist.txt -u https://target.com/FUZZ -ac ``` ### 2. Use Raw Requests for Authentication Don't struggle with command-line flags for complex auth. Capture the full request and use `--request`: ```bash # 1. Capture authenticated request from Burp/DevTools # 2. Save to req.txt with FUZZ keyword in place # 3. Run with -ac ffuf --request req.txt -w wordlist.txt -ac -o results.json ``` ### 3. Use Appropriate Wordlists - **Directory discovery**: SecLists Discovery/Web-Content (raft-large-directories.txt, directory-list-2.3-medium.txt) - **Subdomains**: SecLists Discovery/DNS (subdomains-top1million-5000.txt) - **Parameters**: SecLists Discovery/Web-Content (burp-parameter-names.txt) - **Usernames**: SecLists Usernames - **Passwords**: SecLists Passwords - Source: https://github.com/danielmiessler/SecLists ### 3. Rate Limiting for Stealth Use `-rate` to avoid triggering WAF/IDS or overwhelming the server: ```bash ffuf -w wordlist.txt -u https://target.com/FUZZ -rate 2 -t 10 ``` ### 4. Filter Strategically - Check the default response first to identify common response sizes, status codes, or patterns - Use `-fs` to filter by size or `-fc` to filter by status code - Combine filters: `-fc 403,404 -fs 1234` ### 5. Save Results Appropriately Always save results to a file for later analysis: ```bash ffuf -w wordlist.txt -u https://target.com/FUZZ -o results.json -of json ``` ### 6. Use Interactive Mode Press ENTER during execution to drop into interactive mode where you can: - Adjust filters on the fly - Save current results - Restart the scan - Manage the queue ### 7. Recursion Depth Be careful with recursion depth to avoid getting stuck in infinite loops or overwhelming the server: ```bash ffuf -w wordlist.txt -u https://target.com/FUZZ -recursion -recursion-depth 2 -maxtime-job 120 ``` ## Common Patterns and One-Liners ### Quick Directory Scan ```bash ffuf -w ~/wordlists/common.txt -u https://target.com/FUZZ -mc 200,301,302,403 -ac -c -v ``` ### Comprehensive Scan with Extensions ```bash ffuf -w ~/wordlists/raft-large-directories.txt -u https://target.com/FUZZ -e .php,.html,.txt,.bak,.old -ac -c -v -o results.json ``` ### Authenticated Fuzzing (Raw Request) ```bash # 1. Save your authenticated request to req.txt with FUZZ keyword # 2. Run: ffuf --request req.txt -w ~/wordlists/api-endpoints.txt -ac -o results.json -of json ``` ### API Endpoint Discovery ```bash