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Trojan Horse in Information Security

Last Updated : 19 Sep, 2023
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Any malicious software intended to harm or exploit any programmable device, service, or network is referred to as malware. Malware includes computer viruses, worms, Trojan horses, ransomware, spyware, and other malicious programs. In this article we will understand about Trojan Horse virus.

What is a Trojan Horse?

The name of the Trojan Horse is taken from a classical story of the Trojan War.  It is a code that is malicious in nature and has the capacity to take control of the computer. It is designed to steal, damage, or do some harmful actions on the computer. It tries to deceive the user to load and execute the files on the device. After it executes, this allows cybercriminals to perform many actions on the user’s computer like deleting data from files, modifying data from files, and more. Now like many viruses or worms, Trojan Horse does not have the ability to replicate itself.

For example: 
There was a Trojan that disguised itself as a game. Many users have downloaded this game and that secretly turned into a self-replicating virus. The game was a simple theme-based game, but it started to back up all the files on the drive where the user would access them. The Trojan turned out to be harmless, and it was easy for them to fix. So this was identified as Trojan because it did not disclose the virus.

Now after this many Trojan viruses or Malware came which turned out to be a threat or the most popular malware attack. As these Trojans can be found as versatile, this is used by many online criminals for malware attacks. The Trojans are a bit tougher to be identified. Trojans can be found in MP3 songs that the user may have downloaded, downloading games from an unsecured website, or advertisement that pops up when the user is browsing the page.

Many people have been infected by Trojans without realizing it. This type of Trojans is called Direct-Action-Trojans. It can’t spread to any user because when a virus infects the system show some indications that it has been affected by the virus. 

Another example there is a direct action Trojan name Js. ExitW. It can be downloaded from many malicious sites. The effect of the Js. ExitW is to make the computer fall into a never-ending loop of start and shutdown. The Trojan does not do any damage which could be considered dangerous. But we should be aware that there are many Trojans that are far more dangerous.

Features of Trojan Horse

  • It steals information like a password and more.
  • It can be used to allow remote access to a computer.
  • It can be used to delete data and more on the user’s computers.

How Does Trojan Horse Work?

Unlike computer viruses, a Trojan horse requires a user to download the server side of the application for it to function because it cannot manifest by itself. This means that for the Trojan to target a device’s system, the executable (.exe) file must be implemented and the software installed.

In order to reach as many people’s inboxes as possible, spammers send emails with attachments that appear to be legal and that contain files that propagate trojan viruses. The trojan will install and run automatically each and every time the infected device is turned on the email is opened and downloaded malicious attachment.

Cybercriminals can also utilize social engineering techniques to trick people into installing malicious software, which can then infect a device with a Trojan. The malicious file may be hidden in internet links, pop-up ads, or banner advertisements. The malicious file may be hidden in internet links, pop-up ads, or banner advertisements.

Trojan software can propagate to other computers from a Trojan-infected the computer. A hacker makes the device into a zombie computer, giving them remote access to it without the user’s knowledge. The zombie machine can then be used by hackers to spread malware among a botnet of computers.

A user might, for example, get an email from a friend that has an attachment that likewise appears to be real. However, the attachment has malicious code that runs on the user’s device and installs the Trojan. The user may not be aware that anything suspicious has happened because their machine may continue to function regularly without any signs of it having been infected. 

Until the user makes a certain action, such visiting a specific website or banking app, the malware will remain undiscovered. As a result, the malicious code will be activated and the Trojan will do the required hacking activity. The malware may destroy itself, go back to being dormant, or continue to be active on the device, depending on the type of Trojan and how it was developed.

Examples of Trojan Horse Virus Attacks

Trojan assaults that infect systems and steal user data are to blame for significant damage. Typical instances of Trojans include:

  • Rakhni Trojan: The Rakhni Trojan infects devices by delivering ransomware or a cryptojacker utility that allows an attacker to utilize a device to mine bitcoin.
  • Tiny Banker: With the use of Tiny Banker, hackers can steal users’ bank information. As soon as it infected, it was discovered at least 20 U.S. banks.
  • Zeus or Zbot: Zeus, often known as Zbot, is a toolkit that allows hackers to create their own Trojan virus and targets financial services. To steal user passwords and financial information, the source code employs strategies like form grabbing and keystroke logging.

Uses of Trojan Horse

There are many ways that it can be used :

  1. Spy: Some Trojans act as spyware. It is designed to take the data from the victim like social networking(username and passwords), credit card details, and more.
  2. Creating backdoors: The Trojan makes some changes in the system or the device of the victim, So this is done to let other malware or any cyber criminals get into your device or the system.
  3. Zombie: There are many times that the hacker is not at all interested in the victim’s computer, but they want to use it under their control.

Types of Trojan Horse

Now there are many Trojans which is designed to perform specific functions. Some of them are: –

  • Backdoor trojan: A trojan horse of this kind gives the attacker remote access to the compromised machine.
  • Ransom trojan: This kind of trojan horse is intended to encrypt the data on the compromised system and then demand payment in exchange for its decryption.
  • Trojan Banker: It is designed to steal the account data for online banking, credit and debit cards, etc.
  • Trojan Downloader: It is designed to download many malicious files like the new versions of Trojan and Adware into the computer of the victims.
  • Trojan Dropper: It is designed to prevent the detection of malicious files in the system. It can be used by hackers for installing Trojans or viruses on the victim’s computers.
  • Trojan GameThief: It is designed to steal data from Online Gamers.
  • Trojan I’s: It is designed to steal the data of login and passwords like: -a. skype b. yahoo pager and more.

Other Trojans can also be used like: -Trojan-notifier, Trojan-clicker, and more.

Advantage of Trojan Horse

  • It can be sent as an attachment in an email.
  • It can be in some pop-up ads that we find on the web page.
  • It can be used to allow remote access to a computer.
  • It can be used to delete data and more on the user’s computers.

Disadvantages of Trojan Horse

  • It can’t manifest by itself. It requires the implementation of the .exe files.
  • It remains undetected and starts its execution when the user is doing any online transaction activity.
  • the system or the device where it has been affected will be slow.
  • The user can also experience a direct shutdown of the computer.
  • The user will experience the files to be opening much slower.

Prevention from Trojan Horse

The most basic prevention method: –

  • Do not download anything like the images, and audios from an unsecured website.
  • Do not click on the ads that pop up on the page with advertisements for online games.
  • Do not open any attachment that has been sent from an unknown use.
  • The user has to install the anti-virus program. This anti-virus program has the capacity to detect those files which are affected by a virus.

FAQs on Trojan Horse

Q.1: Who developed the first Trojan?


The first Trojan was developed by computer programmer John Walker in 1975, according to Fourmi lab.

Q.2: Can trojan virus be removed?


There are several techniques to get removed of Trojan malware. You can easily uninstall the malicious software if you are aware of the program it is. However, using antivirus software that can identify and remove Trojans is the most efficient way to get rid of all traces of a Trojan virus.

Q.3: How To Recognize a Trojan Virus?


Without the user being aware of it, a Trojan horse malware frequently stays on a computer for months. However, warning signals of a Trojan infection include sudden changes to computer settings, a decline in computer performance, or the occurrence of odd behavior. The best technique to identify a Trojan is to run a Trojan scanner or malware-removal program on a device.

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