What does it mean

A Trojan horse, often shortened to Trojan virus, is a type of malicious software that disguises itself as a legitimate or harmless application, but in reality, causes damage or provides unauthorized access to the attacker into the computer.

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How Does a Trojan Horse Work?

A Trojan horse typically infiltrates a user's computer or device through email attachments, malicious links, fake software installations, or imitations of well-known applications. Unlike other malware, such as worms or viruses, a Trojan horse does not spread automatically. Its distribution requires the user to download and execute it. However, once the Trojan horse is activated, it can perform various malicious activities without the user's knowledge, such as:

Espionage: A Trojan horse can record user activities, including login credentials, passwords, credit card numbers, or other sensitive information.

Remote Control: An attacker can gain direct access to the computer or device, allowing them to install additional malware, delete or steal data, or execute commands.

Installation of Additional Malware: A Trojan horse can serve as a gateway for other malicious programs that can be installed on the system and cause even greater damage.

Participation in a Botnet: Sometimes, a Trojan horse is designed to turn the infected device into part of a so-called botnet, a network of infected devices used to carry out DDoS attacks (distributed denial of service) or other illicit activities.

Types of Trojan Horses

There are several types of Trojan horses, each designed for a different kind of attack or activity. The most common include:

Banking Trojan (Banking Trojan): This type of Trojan horse targets the theft of financial data, such as bank account login credentials or credit cards.
Spyware Trojan: This type of Trojan horse monitors user activity and secretly sends data to the attacker.
Backdoor Trojan: This variant of the Trojan horse opens a "backdoor" in the computer or device, allowing the attacker remote control of the system.
Rootkit Trojan: This type focuses on modifying system processes and hiding them, allowing the presence of other malicious components to remain concealed.
Downloader Trojan: This Trojan horse is designed to download and install additional malware onto the computer.

How to Protect Against Trojan Horses

Use Strong Antivirus Software: Updated antivirus software can detect and block most Trojan horses.
Regular Software and Operating System Updates: Updates often contain security patches that prevent Trojan horses from infiltrating the system.
Be Cautious When Opening Emails and Attachments: Attachments from unknown sources may contain Trojan horses.
Be Careful When Installing Applications: Users should only download applications from verified sources and avoid apps with unknown or suspicious origins.

Examples of Known Trojan Horses

In the history of cybersecurity, there have been many Trojan horses that have caused extensive damage. Among the most well-known are Zeus (used for stealing banking data), Emotet (originally a banking Trojan, later distributed to spread additional malware), or Flame (a sophisticated espionage Trojan horse aimed at collecting sensitive information).

The Trojan horse is one of the most dangerous types of malware because it exploits human trust to infiltrate the system. Although current security tools can help detect and remove Trojan horses, the best defense is always user caution and adherence to security measures when dealing with files and software from unknown sources.