Wi-Fi Security: Handshake Capture and Deauthentication with Aircrack-ng

Understanding Wi-Fi Security and Attacks

Wi-Fi networks are a cornerstone of modern connectivity, but their security is often targeted by attackers. Tools like Aircrack-ng enable ethical hackers to test network vulnerabilities through techniques like handshake capture and deauthentication attacks. These methods remain critical for assessing Wi-Fi security. This article explores how these attacks work and how to protect your network.

Why Wi-Fi Security Matters

Unsecured Wi-Fi networks are vulnerable to unauthorized access, data interception, and denial-of-service attacks. Ethical testing using tools like Aircrack-ng helps identify weaknesses, ensuring networks are fortified against real threats.

What Are Handshake Capture and Deauthentication Attacks?

Handshake Capture

Wi-Fi networks using WPA/WPA2 encryption rely on a four-way handshake to authenticate devices. Capturing this handshake allows testers to attempt cracking the Wi-Fi password offline. Tools like Aircrack-ng capture the handshake for analysis, revealing weak passwords.

Deauthentication Attacks

Deauthentication attacks forcibly disconnect devices from a Wi-Fi network by sending deauthentication packets. This prompts devices to reconnect, triggering a new handshake that can be captured. Ethical hackers use this to test network resilience.

Why These Attacks Are Used

These techniques simulate real-world attacks, helping administrators identify vulnerabilities like weak passwords or outdated encryption protocols (e.g., WEP). They are critical for penetration testing in controlled environments.

Using Aircrack-ng for Ethical Wi-Fi Testing

Aircrack-ng is a suite of tools for assessing Wi-Fi security, commonly used in Kali Linux or Parrot OS. Below is a step-by-step guide for ethical testing, assuming you have permission to test the network.

1. Setting Up Your Environment

Ensure your wireless adapter supports monitor mode (e.g., Atheros AR9271). Use a tool like airmon-ng to enable it:

sudo airmon-ng start wlan0

This switches the interface to monitor mode (e.g., wlan0mon).

2. Scanning for Networks

Use airodump-ng to identify nearby networks and their details (BSSID, channel, encryption):

sudo airodump-ng wlan0mon

Note the target network’s BSSID and channel for the next steps.

3. Capturing the Handshake

Focus airodump-ng on the target network to capture the handshake:

sudo airodump-ng --bssid [BSSID] --channel [CHANNEL] --write handshake wlan0mon

Replace [BSSID] and [CHANNEL] with the target’s details. The handshake is saved in a .cap file.

4. Performing a Deauthentication Attack

Use aireplay-ng to send deauthentication packets, forcing devices to reconnect:

sudo aireplay-ng --deauth 10 -a [BSSID] wlan0mon

This sends 10 deauthentication packets to the target BSSID, triggering a handshake capture.

5. Cracking the Handshake

Analyze the captured handshake with aircrack-ng using a wordlist (e.g., rockyou.txt):

aircrack-ng -w /usr/share/wordlists/rockyou.txt -b [BSSID] handshake-01.cap

A successful crack reveals the Wi-Fi password, highlighting the need for strong credentials.

Other Tools for Wi-Fi Security Testing

Besides Aircrack-ng, several tools enhance Wi-Fi penetration testing:

• Wireshark: Analyzes captured packets to inspect network traffic. Use filters like wlan.addr == [BSSID] to focus on Wi-Fi data.
• Kismet: A wireless network detector and sniffer, ideal for identifying hidden networks. Run with kismet -c wlan0mon.
• Reaver: Tests WPS vulnerabilities on routers. Example: reaver -i wlan0mon -b [BSSID] -vv.
• Hashcat: Accelerates password cracking for captured handshakes, especially on GPUs. Example: hashcat -m 2500 handshake.hccapx wordlist.txt.

Protecting Your Wi-Fi Network

Understanding these attacks highlights the need for robust Wi-Fi security:

1. Use Strong Passwords

Create complex WPA2/WPA3 passwords with at least 12 characters, mixing letters, numbers, and symbols.

2. Enable WPA3 Encryption

Upgrade to WPA3 for stronger security. If unavailable, ensure WPA2 is used instead of WEP.

3. Disable WPS

Turn off Wi-Fi Protected Setup (WPS) in your router settings to prevent attacks like those using Reaver.

4. Hide Your SSID

Disable SSID broadcasting to make your network less visible, though determined attackers can still find it.

5. Regular Firmware Updates

Update your router’s firmware to patch vulnerabilities. Check your router’s admin panel (e.g., 192.168.1.1).

5 Resources for Wi-Fi Security Testing

• Aircrack-ng Official Site – Official documentation and downloads for the Aircrack-ng suite.
• Kali Linux Aircrack-ng Guide – Tutorials on using Aircrack-ng in Kali Linux.
• Wireshark Documentation – Guides for analyzing Wi-Fi traffic with Wireshark.
• Hack The Box – Practice Wi-Fi security challenges in a controlled environment.
• Wi-Fi Alliance Knowledge Center – Resources on Wi-Fi security standards like WPA3.

Conclusion: Strengthening Wi-Fi Security

Wi-Fi handshake capture and deauthentication attacks, using tools like Aircrack-ng, reveal the vulnerabilities in wireless networks. Ethical testing remains essential for understanding and mitigating these risks. By mastering these techniques in authorized environments and implementing robust security measures, you can protect your Wi-Fi network from threats. Start exploring these tools ethically and fortify your network today.