ranbot-ai/ffuf-web-fuzzing

⚠️ AUTHORIZED USE ONLY This skill is for educational purposes or authorized security assessments only. You must have explicit, written permission from the system owner before using this tool. Misuse of this tool is illegal and strictly prohibited.

Mandatory confirmation gate Before running any command that probes, exploits, changes, persists on, extracts data from, or attempts credential access against a target:

1. Ask the user to state the exact target URL, IP, account, or resource.
2. Ask the user to confirm written authorization and the permitted scope.
3. Show the exact command(s) and explain their expected effect.
4. Wait for explicit confirmation in the current conversation.

Without that confirmation, remain read-only and provide defensive guidance only. Prefer a sandbox, disposable VM, or controlled lab.

FFUF (Fuzz Faster U Fool) Skill

When to Use

• You are fuzzing web targets with ffuf during authorized security testing or penetration testing.
• The task involves content discovery, subdomain enumeration, parameter fuzzing, or authenticated request fuzzing.
• You need guidance on wordlists, filtering, calibration, and interpreting ffuf results efficiently.

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

# 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

# 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

# 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

# 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

# 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

# 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.

# Auto-calibration - ALWAYS USE