What is Trojan Horse and How to Protect Against It?

Trojan Horse, Trojan, RAT, Remote Administration Tool, whatever you call it, it is so scary it seems dangerous and efficient.

In today's article, I will explain to you in more detail how a Trojan Horse works in order to observe what it does and how it does it in order to deduce the means to properly protect itself from it.

We will therefore see the distinctive signs of an infection and how to prevent it effectively.

What is a Trojan Horse?

A Trojan Horse is a healthy-looking program that contains hidden malware. The term “Trojan” is only the English name for “Trojan Horse”.

And yet, here is the definition of the most popular Trojan horse:

“A Trojan Horse is a program that takes control of a computer”

This is the definition commonly accepted and embedded in everyone's head.

However, the initial definition of the Trojan Horse is not exactly this, as we have just seen.

The term “Trojan Horse” comes from a legend in ancient Greece in which the Greeks used a giant wooden horse to conquer the city of Troy.

They actually hid inside the wooden horse so that they could enter the city. Once inside the city, they got out of that horse to open the gates for the rest of their army and destroy the city.

The term “ RAT” comes from Remote Administration Tool ( Remote Administration Tool in French) and is used to take control of a remote computer (without hiding under a healthy appearance).

RATs can therefore be used in a 100% legal way, in particular for remote maintenance, for example, if you have a big problem that only a technician can solve remotely. Moreover you almost all a RAT on your computer, this is the Remote Desktop for Windows.

However, Trojans nowadays allow you to insert RATs discreetly and hidden in the victim's computer. It is therefore at this moment that it is actually possible to take control of the remote computer.

We could therefore say that RATs are legitimate and legal tools (as long as they are used with permission) while Trojans allow you to insert a RAT on a remote machine in order to control it.

How to Protect Yourself Against Trojans?

Here are the prevention methods:

• Install antivirus software and a firewall to fight against the malicious use of these programs: The antivirus detects known Trojans / RATs and the firewall blocks access to ports.
• Don't let anyone physically access your computer: It's very easy to set up a server while you go to the throne.
• Pay attention to the content of e-mail attachments: A “bound” file, so a Trojan Horse may be present.
• Beware of trapped sites: Example with Java Drive-By which allows you to run a program discreetly from a site.
• Be wary before clicking on a program: The ultimate instruction (mistrust and awareness) is still valid.

And finally, if your mouse moves on its own, if your keyboard starts typing on its own, or if files/programs open on their own, you also have a worrying sign of Trojan horse contamination.

Go Further

The program used was used for demonstration only and was of course not used on another computer than mine, and was not hiding.

It is also clearer and more precise to learn by doing than to follow simple instructions “don't do this, don't do that”, without knowing why not to do it. In addition, we now know why and how to look for signs of infection.