Evil twin attack: Definition, detection, and prevention

What is an evil twin attack?

An evil twin attack is a cyberattack in which a hacker creates a fake Wi-Fi access point that mimics a legitimate network and tricks users into connecting. Threat actors create such hotspots to infiltrate a device and gain unauthorized access to sensitive data.

How does an evil twin attack work?

Here’s a breakdown of how an evil twin attack works:

• Fake Wi-Fi network setup. A hacker finds a popular location with free Wi-Fi, such as cafes, airports, or libraries. They copy the name (SSID) of the authentic access point and set up a new hotspot (evil twin). A hacker usually places the fraudulent network in easily accessible locations to spread a stronger connection signal than the original one and to entice more users.
• Fraudulent broadcasting and user connection. The attacker makes the evil twin visible to unsuspecting users. Devices previously connected to the network attempt to connect to the evil twin automatically.
• Traffic monitoring. A hacker gains the ability to monitor the victim’s internet traffic and capture personal information that users transmit over the network.
• Data exploitation. When a threat actor gains access to your sensitive information, they can sell it on the dark web and commit identity theft or financial fraud.

An example of an evil twin attack

To help you comprehend the essence of an evil twin better, here’s an evil twin attack example:

Imagine a student coming to a library for casual study and sitting in the same place they always do. They start setting up their Wi-Fi connection but don’t remember the SSID of an access point they’ve connected to before. The Wi-Fi settings display "Library_FreeWiFi" and "Library_WiFi," and the student connects to "Library_FreeWiFi," which generates a stronger connection signal than "Library_WiFi." In this case, the access point "Library_FreeWiFi" is an evil twin network set by a hacker, displaying a similar SSID to the original one.

Now, a malicious actor can monitor your online activity and access your private information depending on what websites you visit while connected to an evil twin access point.

How to detect an evil twin attack

Unfortunately, evil twin Wi-Fi access points are difficult to detect without specialized sniffing tools. However, some signs may reveal an evil twin attack and help you avoid fishy connections. Here’s a list of essential tips to help you detect an evil twin access point:

• Keep an eye on network names (SSIDs). Always check if the access point SSID matches the one provided by the venue. And look for SSID duplicates that may give away a lurking evil twin attack.
• Ask the staff. If you’re unsure about the legitimate access point, ask the staff. They will confirm the correct network name.
• Watch out for login screens. When connecting to a public Wi-Fi access point, a login screen asking for your personal details may be a massive giveaway of an evil twin attack. Legitimate networks usually don’t ask for login credentials unless it is a captive portal, for example, in a hotel or airport.
• Check MAC addresses. Legitimate access points have unique media access control (MAC) addresses. Before connecting, compare the MAC address of a network you’ve connected to before and the current one to detect an evil twin.
• Monitor network connectivity. Error messages while connected to a network and frequent disconnections could indicate that you’re connected to an evil twin. Such issues may be caused by an attacker trying to intercept or redirect your traffic.
• Be wary of SSL certificate warnings. SSL certificate warnings or security alerts when accessing websites may give away a man-in-the-middle attack.

Regular monitoring and proper education may help you protect your devices from the devious evil twin.

What to do if you become a victim of an evil twin attack

If you suspect that you’ve become victim to an evil twin attacker, take the following steps to prevent the theft of your personal data, identity, and banking credentials:

• Disconnect from the suspicious network immediately.
• Change your passwords and set up two-factor authentication (2FA).
• Perform a full system scan with an up to date antivirus software.
• Contact your local police department.
• Reach out to your financial institution (if affected).
• Monitor your accounts for suspicious activity.

Following these steps may ease your mind, put a layer of protection on your possibly compromised data, and prevent the hacker from taking advantage of other unsuspecting users.

How to prevent future evil twin attacks

Preventing an evil twin attack primarily involves caution when connecting to public Wi-Fi networks and detecting an evil twin before connecting. Use the following tips to prevent future attacks:

• Turn off the automatic Wi-Fi connection. Disable auto-connect on your mobile devices and laptops to prevent them from connecting to open networks.
• Refrain from unsecured hotspots. Avoid unsecured networks that don’t require a password to connect. This can safeguard you from evil twin attacks, eavesdropping, man-in-the-middle attacks, and malware distribution in your device.
• Use a reputable VPN. Use a trustworthy VPN to encrypt your internet traffic, making it hard for hackers to intercept your traffic and steal information.
• Use mobile data. Use your own Wi-Fi hotspot to run errands that require logging in to sensitive accounts or involving your financial information.
• Avoid connecting to personal accounts. If you don’t have mobile data, it’s better to wait for a secure Wi-Fi network to connect to personal accounts.
• Ensure you only visit HTTPS websites with a VPN. Stick to HTTPS websites with a padlock icon in the browser address bar. They encrypt communication between a web browser and a server.
• Set up 2FA for your online accounts. Secure your online accounts with 2FA, requiring an extra verification factor to gain access to an account and protect against unauthorized access.
• Update your devices regularly. The newest operating system versions usually include the latest security patches protecting against known cyber threats.

These tips can significantly reduce the risk of falling victim to an attacker. However, vigilance and knowledge are power that may be the cornerstone of protection against an evil twin attack and other online dangers.