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Understanding the classic and dangerous man-in-the-middle attack

It's no news that cybercriminals invent new tricks and tactics daily to attain their sinister objectives: to harm unprotected Internet users by stealing personal data, sensitive documents, and often even money. But this doesn’t mean that old scams no longer work. Certain techniques have existed for over a decade and are still highly efficient and successfully used by criminals.

A prime example is known as a MitM, or man-in-the-middle, attack. And the name of the threat explains it all: a cybercriminal intercepts a data exchange between a victim and a recipient, whether another Internet user, in the case of a conversation, or a server receiving an email or a password, to steal the transmitted data unnoticed.

How it works

Several strategies can be used to execute a man-in-the-middle attack, but they are all based on the same principle: cybercriminals place themselves in the middle of data transmission. 

For a detailed insight into how bad actors operate, let's take a look at an example of one of the most common strategies. First a criminal visits somewhere busy – like a library, an airport, or a coffee shop – and sets up a fake access point to a supposed public Wi-Fi network. The network is given a name that won’t arouse suspicion, like that of an establishment, making it seem legitimate.

Once the victims are connected to this network, the cybercriminal uses specific tools to intercept and spy on everything the targets are doing. This is just the gap required to view and steal chats, passwords used for banking apps, sensitive files, and so on. People very often don’t even realize they’re under attack!

This is called Wi-Fi interception, but as mentioned earlier, there are several ways to launch a man-in-the-middle attack. Other examples include IP spoofing, browser cookie theft, and now even a new man-in-the-browser (MitB) attack, where malware redirects your browser to a fake login page to capture everything you enter into the form.

Learn how to protect yourself

Fortunately, there are a few simple tips that can help you avoid a man-in-the-middle attack. The first of these is to never trust public Wi-Fi networks, especially when having conversations or conducting sensitive operations like banking transactions. Always use your own mobile network when on the road or in public places. It is worth investing in a good 4G or 5G Internet plan if you constantly work away from home or the office.

Also, don't forget VPNs! This type of software blocks man-in-the-middle attacks using encryption to form a secure tunnel to protect the communication between your device and a server, "scrambling" the data so that the "man in the middle" can’t interpret it. This is another crucial investment that will save you if there’s no choice but to use an unfamiliar Wi-Fi connection.

Finally, it is also worth properly configuring your router to enhance your security at home – after all, you never know when a stranger with bad intentions passing by might try to access your Wi-Fi and stage a man-in-the-middle attack in your own home!

Article originally written in Portuguese by Perallis Security Content Team: Entenda como funciona o clássico e perigoso ataque man-in-the-middle — Perallis Security