Trojan (Meaning and Explanation)

We explain what a Trojan is and the ways in which this malicious software can be removed. Also, their types and how to protect yourself from them.

Trojan Virus — Trojans allow a person to access another user's information.

What is a Trojan?

A Trojan (or trojan horse) is a malicious computer software that appears to be a legitimate and safe program but when a user executes it, it gives the attacker remote access to the computer. The term is used in computing and refers to the Trojan horse used by the Greeks in Homer's Odyssey.

This malware (malicious file) allows the attacker to access computer information in most cases, to copy and steal personal data.

A user's computer can become infected with a Trojan when they open suspicious email attachments or run content from unknown websites. Unlike viruses or worms, Trojans are characterized by not being able to replicate automatically.

Purposes of Trojans

Trojans are widely used by virtual criminals or cybercriminals to access confidential data, account theft and, mainly, money theft.

Some of the purposes for which a Trojan is created are:

Using the computer to send spam.
Install other malicious programs.
Take screenshots.
Observe keyboard keystrokes.
Extract photos from webcam.
Erase or damage the hard drive.
Delete or modify data.
Steal login details and confidential information and then forward it.

Types of Trojans

There is a wide variety of Trojans that perform certain functions or attack different areas of a computer. The most common are:

Backdoor Trojan. Type of Trojan through which the attacker has access to the computer (he does so by generating a backdoor or backdoor) and execute actions remotely.
Download Trojan. Type of Trojan that downloads unauthorized content to the infected computer, which in many cases is other malicious software.
Banking Trojan. Type of Trojan that copies and steals user data from banking or online payment sites.
Trojan info and password stealer. Type of Trojan that copies and steals passwords and user information.
Distributed Service Trojan. Type of Trojan that sends requests from infected computers to a specific web page, to saturate it and cause it to crash.
Clicker Trojan. Type of Trojan that opens certain websites without the user's consent to give more visits to that page.
keylogger trojan. Type of Trojan that records the keystrokes made by the user on the keyboard to copy and steal the information that the user sends through this external device.

How to know if a computer is infected?

Some of the guidelines that indicate that a computer has a Trojan are:

The computer restarts or turns off by itself.
The system works very slowly.
The operating system does not start.
Files on your computer disappear or are modified.
Windows open with advertising and/or pornography.
Pop-ups with strange messages appear constantly.
Programs run on their own or stop working.
Websites open suddenly.
The default search engine of the web browser is altered.

How do you remove a Trojan?

When a computer is infected with a Trojan, the execution of some computer functions is affected and the user runs the risk of having personal data copied and stolen. For this reason, cleaning your computer of Trojans is essential and can be done by following the following steps:

Download and install an updated antivirus.
Disconnect the equipment from the Internet, whether it is connected via Wi-Fi, with an ADSL modem or a network card.
Open the internet browser (although offline) and clear the cache and cookies. It is important to do this step with each browser you use.
Run the antivirus in “safe mode”. From there, the antivirus will scan the computer. This activity may take several minutes, because the antivirus will check all the files on the computer in search of any malicious ones.
When the antivirus finishes, the harmful files it detected will be displayed. Here the antivirus will give the option to: delete, quarantine or ignore the files found. You must always choose the delete option.
The antivirus will then ask you to restart your computer.
Then the equipment must be reconnected to the internet.

How to protect yourself from a Trojan?

It is important to take into account some tips or recommendations to avoid opening Trojan software, for example:

Do not open files that arrive by email, except those whose sender is known and known to be safe.
Do not visit dubious or unknown websites.
Use caution when downloading files using sharing programs such as P2P (Peer to Peer). It is always advisable to scan each file with an antivirus before opening or downloading it.
Update your antivirus frequently as new updates always appear.
Perform periodic scans with the antivirus.
Use firewall, a security device that operates between networks to prevent malicious transmissions from one network to another.
Do not install a program if the manufacturer is unknown.
Download only original programs to your computer.
Use different web browsers.

Difference between Trojan and computer virus

The term Trojan is often associated with the idea of a computer virus, but it is important to mention that a Trojan is not a type of virus.

Although in both cases they are malicious software that causes damage to the computer and enters it without the user's consent. The main difference is that the virus can replicate automatically while the Trojan does not. In addition, viruses enter the computer with the intention of destruction and Trojans seek to steal information or open the computer's door for other malicious software to enter.

What is spyware?

Spyware or spyware is a type of application that is installed on a computer, without the user's consent in order to collect information and then share it with other people for commercial purposes.