The Public Wi-Fi Trap: How Evil Twin Attacks Steal Your Credentials Without You Realizing

Public Wi-Fi networks in cafes, airports and hotels are very convenient tools to stay connected outside the home. However, their ease of access makes them fertile ground for digital espionage. One of the simplest and most effective methods to intercept network traffic in these environments is the Evil Twin attack.

This type of attack is based on wireless spoofing and deception of automated devices.

How does an Evil Twin attack work?

The Evil Twin attack is typically executed in four critical phases:

1. Reconnaissance: The attacker scans the public wireless network environment to find a legitimate, busy access point, noting its network name (SSID) and broadcast channel.
2. Creation of the clone: Using common network hardware and free software, the attacker deploys a Wi-Fi access point with the same name and configuration as the legitimate network, often broadcasting with a higher signal strength to become more attractive.
3. Disassociation Attack: The attacker sends forced deauthentication frames to devices connected to the real Wi-Fi. This momentarily disconnects users from the legitimate network.
4. Automatic connection: When trying to reconnect automatically, victim devices choose the closest access point with the strongest signal, which in this case is the attacker's.

Data Interception and Captive Portals

Once the user connects to the Evil Twin network, the attacker acts as a man-in-the-middle for all of their traffic. The cybercriminal can redirect requests to fake login portals (captive phishing portals) that ask for email passwords, social networks or bank card details.

Even if the user visits sites protected by HTTPS, attackers with sophisticated tools try to degrade the connection (SSL Stripping) or present fake SSL certificates to inspect the traffic in plain text.

Protection measures for the user

To browse safely and avoid falling into malicious twin networks, take the following precautions:

• Use a robust VPN: A Virtual Private Network encrypts all your traffic from your device to the destination server, making it undecipherable to the fake Wi-Fi administrator.
• Disable auto-connect: Configure your devices to never automatically connect to previously known open or public networks.
• Pay attention to browser warnings: If your web browser displays an "Invalid security certificate" or "Insecure connection" alert when you enter a portal, immediately disconnect from the network.