What Is Trojan?

There are many pros and cons of technology, but the biggest setback for it is viruses. Viruses are computer programs that, when inserted into a computer device, start replicating and multiplying themselves. Soon after, it will spread in the whole device, like cancer, and corrupt it from the inside out.

Trojan or trojan horse, as it is often referred to, is also a type of computer virus. It might be one of the most common computer viruses as it is often difficult to differentiate between a trojan virus and a computer file. You may even have a trojan on your computer right now! Read till the end to learn about these.

What Is A Trojan?

Trojan or Trojan horse is a computer virus or malware often disguised as genuine computer software. The main aspect of this virus is to steal, corrupt, damage, or harm the computer or the technological device it has been inflicted on.

When a trojan virus attacks the computer, it is often downloaded by the user. The user may think that they are downloading authentic software or file, which is, in fact, trojan malware in disguise.

There are often debates about whether a trojan horse should be classified as a virus or malware. A computer virus’s main quality is that it can execute and multiply itself. But the trojan horse cannot execute itself. It has to be downloaded by the user. After the initial download, it can cause harm to the software.

How Does A Trojan Virus Work?

The name trojan may spike the memory of the trojan horse from the greek methodology. According to the Greek myth, Troy built a wooden horse that was pulled into the city by the people of Troy. When the sun went down, the soldiers hiding inside the trojan horse appeared and let their fellow soldiers inside the city. Together the force was able to attack and plunder.

A trojan horse virus or malware is the same. It is an impersonation of an authentic software or file, which is then downloaded by the user like the people of Troy pulled the horse inside the city. Once it is downloaded, it spreads throughout the device and causes harm.

As the trojan virus cannot download and execute itself, tricky techniques are used to convince the user to download them. The most common way to convince the user to download the malware is through convincing ads or links.

Recently, new and innovative tactics are being used, such as emails. A trojan virus is added to the email attachment, which the user downloads. The email may seem important, containing key information as an attachment.

Once the virus is injected, it remains undetected until it performs the specific action for which it is made. It is also possible that it deletes itself after acting. Additionally, there have been cases of the trojan virus infecting a computer and making it a zombie computer controlled by someone else. Then it can infect other computers and turn them into a bot. Soon a network of bots will be formed, which is referred to as a botnet.

Examples Of Trojan Horse Attacks

In computing, the trojan virus was founded in the 1980s. It was at first referred to as a pest trap or spy sheriff. During those times, BBS systems were used- bulletin board systems. A phone line is used to affect a BBS with a trojan virus.

BBs were a system used to run software of different kinds, and with the help of a phone line, it could be affected by the trojan virus. After infection, the attacker can perform many different actions, like downloading or uploading malicious information or stealing information.

After that, the trojan virus could affect more computers with the help of pop-up ads or warnings instructing the user to download different software to protect their computer. The issue with this type of virus is that, once it is installed, It cannot be removed from the computer. Trojan horse virus can be easily detected by any antivirus but cannot be removed even if system restore is done.

Furthermore, if the user tries to remove the trojan horse software, it reinstalls itself with the help of hidden files in the computer. The most important event regarding the history of the trojan horse virus was the arrest of a man in 2002 for having 172 photos of child pornography on his computer.

The case remained ongoing for a year, after which the court accepted his defense that the files were not downloaded by him and were the result of trojan horse malware. This case gave an idea of the severity of damage that can be done with the help of this virus once it is executed. Additionally, it is almost impossible to remove it.

Types Of Trojan Attacks

There are many different types of trojan horse virus, such as;

Spy Trojan

As the name may indicate, this trojan virus is designed to spy on a computer. Certain spying actions may include:

  • Watching the user’s actions.
  • Taking screenshots.
  • Saving login details.
  • Checking the applications used by the user.

Backdoor Trojan

Backdoor trojans can give the attacker remote or backdoor access to the affected computer. With the help of this access, information can be stolen, files or software can be downloaded, the virus can be uploaded, or even the infected computer can be rebooted.

The backdoor trojan’s key usage is to create a zombie computer. This zombie computer can then affect other computers and create more zombies, also referred to as ‘bots.’ A network of bots is classified as a ‘botnet’ that can be used according to the attacker’s wishes.

Exploit Trojan

This type of trojan malware exploits the weak link in the infected computer. This type of virus is made up of specific code or data that can take advantage of the issue found in the computer.

Mailfinder Trojan

This malware is used to attack and steal the email addresses found on a computer. Their login details are stolen and can be used for malicious purposes.

Downloader Trojan

Like the name gives an idea, a downloader trojan can download malicious programs into the affected computer. This can either be malicious content or even more trojan malware of different kinds.

Banker Trojan

This banking trojan is specifically designed to attack the banking information found in the computer system. This information includes a bank, debit, credit card, or login details.

Infostealer Trojan

One of the most hazardous types of trojan virus, it can either download more trojan malware into the computer or make it impossible for the already downloaded malware to be detected. If a virus cannot be detected, it can harm for longer.

Remote Access Trojan

This type is similar to a backdoor trojan. But unlike a backdoor trojan, remote access trojan has a malicious code that can give the attacker complete hold of the device. This access can be used for various wrong actions like spying, spreading malware to other devices, downloading malicious programs, or stealing information.

Fake Antivirus Trojan 

It is intricately designed to look and act like antivirus software. This fake antivirus software removes all the non-existent viruses that threaten it, such as authentic antivirus software. It also causes a financial loss by asking the user to pay and harming the computer simultaneously.

DDoS Trojan

This type of trojan virus acts like another computer virus; Distributed denial of service or DDoS virus. It sends numerous fake messages to the computer, causing an overwhelming effect. The computer cannot handle so many requests at once, which causes it to hang or crash.

Game Thief Trojan

This type of trojan horse malware is used to steal gaming information from online gamers. This can be the login details or more of the well-known gamers.

Ransom Trojan

With this trojan, the attacker can lock essential information or the whole device for a certain ransom. Once the ransom money is paid, the attacker unlocks the information or the device. This type of trojan virus is used to attack large companies that have important information saved online or businesses that are based online.

Instant Messaging Or IM Trojan

This trojan virus attacks and steals information, specifically the login details of instant messaging applications like skype, messenger, yahoo pager, and more.

Rootkit Trojan

The main purpose of this type of trojan is to let the malicious malware remain hidden and undetected so it can work easily without harm.

Short Messaging Service or SMS Trojans

This type of trojan malware affects mobile phones and enables the attacker to send messages to different contact numbers, including premium devices which causes an increase in the cost. It can also intercept messages.

Fake AV Trojan

This trojan virus inserts itself into the windows bar and pops up an official-looking notification. The fake notification alerts the user regarding some issues in the computer. When the user follows the steps told by the alert to solve the issue, they install more malware into the computer.

Bifrost Trojan

It is a remote access trojan (discussed above) or RAT trojan that allows the attacker to change or alter components in the computer.

Magic Lantern

It is one of the government-used trojan viruses. The FBI created it to monitor criminals by affecting their computers.

Zeus Trojan

This type of trojan virus remains the most dangerous variant yet. This crimeware toolkit allows attackers to make their version of the trojan horse virus depending on the type of action they want it to perform.

How To Identify Trojan?

Trojan horse is one of the most dangerous computer viruses used worldwide to perform several cyber attacks. Therefore, learning about the key features to identify a trojan horse malware is essential to prevent further attacks or solve the issue. You can identify Trojan computer viruses in several ways, such as;

A web application firewall or WAF is a modern and innovative technique used to detect and block trojans, especially when it tries to contact the attacker. Furthermore, a WAF is a highly useful software to block and prevent trojan attacks. WAF does this by blocking downloads from unknown sites and alerting users regarding suspicious activity.

Another way to identify and prevent a trojan attack is by using an endpoint protection platform. This technique uses a next-generation antivirus that works perfectly with the device. This antivirus then runs through the system to identify and neutralize any dangerous activity, including a trojan virus. It is also a highly effective way to prevent further attacks (not specifically trojan virus only).

Even though one could claim that a trojan horse virus is highly intricate and may be difficult to learn, find, and neutralize, it is not impossible. And often, even a basic complaint of a slow device or strange behavior can lead to running a behavior analysis to search for the issue. This can lead to the identification of the trojan virus. After this, the user can work to find a solution to the problem.

Threat hunting is a technique used by large cooperations and businesses worldwide as a preventive measure. It includes using a network of highly trained security analysts running large-scale security checks across the computers in an organization to search for any security threats in the system. You can use these checks to look for a specific virus like the trojan or as a preventive technique to protect the computer system from possible attacks.

In addition to that, some simple and basic features of the trojan that any user can identify are;

  • Unusual activity that the user does not perform.
  • Slowing down of the system or not responding as fast as it used to,
  • Some changes made in the device, such as change of the background,
  • Unusual downloads that the user does not make,
  • The antivirus is turned off,
  • With the increasing amount of pop-ups on the device,
  • The computer or the device begins to operate on its own, such as the keyboard and mouse, without being touched as if controlled by someone else.

These basic and advanced techniques can be very helpful when dealing with an intricate and complicated virus like the trojan horse.

How To Protect Your Computer From Trojan Attacks?

It is important to keep your computer safe from any possible attacks, and it is essential to learn how to protect our devices from trojan horse malware. Several steps can be followed as a precautionary measure;

First and foremost is not to visit any unsafe or unknown websites. There is a possibility that this website may have undetected viruses that can harm your device. Furthermore, many antivirus softwares and websites can alert you if a website is unsafe. Making use of these sites or software can keep you protected.

It is essential to keep all your accounts password protected, whether it be your window login, bank account details, emails, or gaming logins. Ensure every password is unique and complex, making it difficult to hack into.

The most common way trojan horse malware is downloaded on a computer is through pop-up ads and email attachments. Therefore to reduce the risk of getting infected by a trojan horse is to make sure that before downloading it, the software is authentic and safe.

It is also important to ensure that the email received is from an authentic source. Furthermore, before opening suspicious emails or downloading any software, scan them with antivirus software.

Apart from that, keeping your computer’s security software updated is essential. You can do this by updating the software as soon as a software update is available. There are many different trojan viruses available that can exploit the weaknesses found in a computer. The most common weaknesses are security weaknesses that can be combated by installing antivirus, not downloading unknown software, and keeping the computer up to date.

It is smart to back up all your computer data in an online software or another device. This backup can be useful in case of an attack. If the data is affected due to any antivirus attack, it is already backed up and hence not lost. Additionally, many security software runs security checks at intervals to search for any possible malware in the computer. You can schedule these checks yourself or instruct the app or software to follow these checks at a particular time.


While a trojan horse virus is complicated and can harm devices, such as computers, laptops, or mobile phones, it is not impossible to be prevented from guarding against. Therefore, a user should be aware of all the preventive measures that one can take to prevent any malicious virus or malware from attacking the computer.

There have been many incidents in which mobile phones have been affected by the trojan horse virus. In the past, only computers and laptops were susceptible to trojan malware attacks. Still, with the increasing use of mobile phones, there have been unsuspected downloads by the user, which lets the virus enter the device undetected.

As the attacker can easily access the mobile device, they can download suspicious data into the attacked phone and steal or download information. In this era of technology, people carry all their useful information on their mobile phones, including bank account information and login details.

This useful information can be stolen by downloading from suspicious websites. Therefore, cell phone users must be informed about the latest cybercrimes and the preventative measures that can be taken to avoid them.

Derik Belair

As President and CEO, Derik leads the vision, strategy and growth of Augmentt. Prior to founding Augmentt, Derik was the Vice President at SolarWinds, leading the digital marketing strategy for SolarWinds’ Cloud division. Derik has been working in the channel for over 20 years, starting his career as a channel sales rep at Corel Corp. and eventually becoming the first employee at N-able Technologies in April of 2000.
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