What Is A Trojan Horse?

Have you ever seen a notification that states "Your Computer Might Be Infected By Trojans" and wondered what is a trojan horse?

Well to clear things up, Trojan Horse is a form of Malware that can cause some serious damage to your personal information stored on your desktop/laptop.

Over the course of this article, I'm going to explain what Trojan Horse is, what it does and how you can protect your data from being infected by it.

In order to understand what a Trojan Horse does, you must first learn about its history, the types of Trojan Viruses out there, and finally how you can prevent being infected by a Trojan Horse.

So What Is This Trojan Horse, Is It A Virus Of Some Sort?

Time for a quick story, Like all famous people and companies in history, even I was once a target of this dangerous program. This took place in the year 2008, 1 month after I got an internet connection at my home.

I was casually checking my Inbox (I was just 13 years old back then, I still don’t understand why I needed an email id as I didn’t have any contacts other than my family), and I came across an email that said free games inside (Obviously a scam).

I was tempted to check and I opened the attached link which redirected me to a file-sharing site. I navigated through all ads and finally landed on the download page. I clicked the download file and then clicked open. I saw a window that opened up and closed itself for a second.

I thought that maybe the file didn’t execute correctly and ran it three times. Each time I saw the same one-second popup window. I was finally fed up so I just shut down the computer and then went out to play.

Later in the evening, I turned on my PC and to my surprise, it was very laggy. The “My Computer” icon took minutes to respond to, and once it opened I saw that most of my files had weird names and the overall size of the files had decreased as my antivirus was not up to date it wasn’t detecting anything suspicious.

I called up our tech guy and once he saw the system, he broke the bad news to me - The computer was infected with Trojan. I had no choice but to format my entire hard disk and reinstall the OS and software from scratch

Moral of the Story: Don’t fall for free stuff and always think before downloading anything suspicious

So even though the Trojan Horse is referred to as a virus, it’s a type of malware that can wreak havoc in your digital world. A Trojan Horse is usually shared by cyber-criminals via file-sharing sites or email attachments.

It disguises itself as genuine software and sits silently on your system. Once activated, it opens backdoor access to your system allowing hackers to spy on you or steal your data entirely.

The Trojan Horse Malware is capable of:

Copying Data

Modifying Data

Deleting Data

Disrupting your computer’s performance or the overall network.

How does a Trojan Horse work

The user must download the server side of the malicious application before a Trojan horse may infect a PC. The Trojan horse is unable to appear on its own. The program must be installed and the executable file (.exe file) must be used for the attack to be launched against the system.

To persuade end users to download a malicious application, social engineering techniques are frequently utilized. The download trap might be present in banner adverts, internet links, or pop-up ads.

However, the most common method for disseminating Trojan Horse are emails and email attachments that appear to be harmless.

Developers of Trojan horses routinely send their emails to hundreds or thousands of recipients using spamming methods. The Trojan server will be installed and will launch automatically each time the computer turns on as soon as the email has been opened and the attachment downloaded.

Additionally, a Trojan horse-infected computer may continue infecting additional machines, forming a botnet.

An innocent computer is made into a zombie computer, which has the advantage that the user is unaware that someone else is in charge of it while it is in use. These zombie machines are used by hackers to spread more malware and build an entire network of zombie computers.

Not just users of laptops and desktop computers are susceptible to a Trojan horse attack. Trojans can use mobile malware to attack mobile devices like smartphones and tablets. By infecting these Wi-Fi linked devices, an attacker might reroute traffic and use them to execute cybercrimes.

Types of Trojan Horse

Now that you know what it does, let's take a look at the types of Trojan Horse Malware out there...

In most cases, Trojans are usually shared through emails and file-sharing software. There are many other ways a Trojan can attack your system.

So just like Pokemon, Trojans are classified based on the medium of attack.

A few of the known (and common) types are as follows:

Backdoor Trojan - It attacks the computer and opens a doorway for hackers to access the system. With this access, hackers can modify and even delete files. They can also remotely shut down or restart the system.

Distributed Denial of Service (DDoS) Attack - Distributed Network Attacks are often referred to as Distributed Denial of Service (DDoS) attacks. This type of attack relies on sending multiple requests to generate fake traffic, thus bringing down the network. In the case of a Trojan, the traffic is generated from an infected or a group of infected computers.

Trojan-Downloader - As the name suggests Trojan downloader targets an already infected computer by downloading malicious programs to further damage the computer.

Fake AV Trojan - This Trojan disguises itself as a genuine antivirus program. It demands money from the user from removing threats (which in reality doesn’t exist).

Trojan GameThief - The targets here are the online players, Hackers use this Trojan to extract account information from the players.

Trojan Ransom - In this case, the cyber-criminal attacks the computer and locks its performance under a certain threshold for a certain ransom. The cyber-criminal unlocks the performance once the ransom has been paid.

Trojan-Spy - As the name suggests the Trojan allows the hacker to spy on your computer. It allows him/her to take screenshots, read keystrokes, etc.

Rootkit Trojan - A rootkit hides or obscures an object on your infected computer. This gives more time for malicious programs to destroy the computer.

Infostealer Trojan - Just as the name suggests, the Infostealer Trojan will infect your computer to steal your personal information. These are normally Trojans that are used by hackers to steal data from their victims.

SMS Trojan - A SMS Trojan is one such Trojan that is designed to infiltrate and infect your mobile device. These can intercept text messages and can send out messages to your contact list without any prior warning.

Trojan Banker - The Trojan Banker is meant to target and take control of your finances and banking details. These Trojans can enter your bank account and can steal your card information, along with other personal financial information that can be used against you.

Remote Access Trojan - This type of Trojan will provide your attacker with unfiltered access to your computer and personal files via a remote network connection.

Two of the most dangerously famous Trojan Horse Malware are the Zeus and Emotet Malware.

Zeus and Emotet Trojan

No, it’s not the Egyptians vs the Greeks epic war story, Zeus and Emotet are the two dangerous examples of Trojan Malware.

Emotet was a Trojan that became famous in 2018. It was so threatening that the U.S. Department of Homeland Security classified it as one of the most dangerous and destructive malware to ever exist.

The Emotet Trojan would spread itself through email attachments and target cryptocurrencies and bank logins. The worst hit was the Chilean bank Consorcio, with damages of $2 million, and the city of Allentown, Pennsylvania, with losses of $1 million.

Zeus on other hand was a Trojan that was created in 2007, It was distributed through malicious files hidden in fake websites and emails.

It stole information by recording keystrokes and was widely used in cases of credential and password theft, which affected banking and email systems. Companies like Amazon and Cisco were also impacted by its attacks.

The total loss that has occurred through Zeus and its variations is estimated to be more than $100 million.

Phew, that sounds dangerous, is there any way I can identify and protect myself from this menace?

How To Check If I'm Infected With A Trojan Horse?

Yes, there are quite a few ways to identify a Trojan on your system. You can consider these as the symptoms:

Weird Messages and Pop-ups - Have you noticed any strange popups on messages on your OS? If Yes, then your machine might be infected with Trojan.

Extremely Slow Computer - The common symptom of a Trojan or any other virus for this matter is a slow computer. You might blame it on your CPU or a broken hard disk but in most cases, it’s been infected with a Trojan.

Interrupted Internet Connection - You open a website and it takes ages to open, It’s so slow that you feel nostalgic about the time when the dial-up internet connection was a trend. Trojan usually downloads malicious programs in the background thus reducing the speed of your internet connection. So if you’re getting that feeling right now then yes your machine has been infected.

Unusable Apps - The programs just don’t respond no matter how many times you open them. And sometimes it opens after a few minutes. This is another common symptom of an infected computer.

Missing Files - You boot your computer and you find that your favorite game or some important document is missing. Before you blame it on your younger brother (or any other family member for this matter), you might have to accept that it’s a Trojan that has started doing its activity. This is one of the scariest symptoms to happen to any computer.

Your Antivirus is Gone and Firewall Disabled - When all this is happening you might be wondering why your antivirus is not detecting anything. Well if you have seen any generic action movies (Die Hard, Mission Impossible, etc), then you must have noticed that bad guys first take out the security system. Similarly, the Trojan targets the security system AKA the antivirus and disables it so that it can start its nefarious activity on your system.

Language - Yes, this is the worst thing that can happen to anyone. You boot up your computer and it’s in a different language. Navigating through all the menus and icons that are in a foreign language and second-guessing can take a toll on your mental health. So if it has happened to you, then I’m sure now you know the reason.

Computer Operating on Its Own - Well, your computer doesn’t become self-aware like those awesome Terminator movies (Only the 1st two movies are awesome by the way, the rest are just copy-paste of the prequels in case if you’re up for a debate) but it does start acting out weirdly. Windows opening on its own, random reboots, etc are just a few of the common scenarios that take place once a computer is infected.

Protecting Your Computer From A Trojan Horse Malware

So if you’re one of the lucky few who hasn’t felt the wrath of the Trojan then good news you can protect yourself now.

Please follow the below steps to protect your computer:

Never under any circumstance open an attachment from an unknown person, no matter how tempting it is (Trust me when I say this).

Keep yourself safe when browsing certain websites, make sure you download the right file. Trust your guts (and your common sense) when swarmed with multiple download buttons on a page.

Always keep your computer and software up to date.

Install an Antivirus - I would recommend Bit-Defender or Nod32 Antivirus in case you’re ready to shell out your money. Nod32 is my personal favorite because the robot on the home screen reminds me of the classic I, Robot movie (just joking), it’s because it’s a really good antivirus that takes a minimal amount of your resources, and it's very user-friendly. In case you’re broke or you follow basic browsing practices then you can use a free antivirus like Avira and Microsoft Defender (which comes built-in on Windows).

Switch to Linux - This is more of a personal preference, it’s not like Linux is safe from Trojan (Even though people mostly believe that Linux is immune to viruses and malware). Most of the viruses or malware are designed to target the Windows OS as they’re more popular and commonly used. On the other hand, Linux is used for running servers, by software developers and tech enthusiasts like me and even though there are few viruses that are designed to target the Linux system, the probability is very low thanks to the effort of Linus Torvalds and his community of Linux enthusiasts.

Protect all your information by regularly changing your passwords. Make sure to use unique passwords that are a combination of numbers, letters, and special characters.

So if you’re bored of seeing the same old start button, you can switch to Linux for a new experience. Anyway, it’s a topic for a separate discussion.

These are the things you should NOT do

Don't visit unsafe websites. If you have an anti-virus app on your desktop/laptop then it should notify you when you're about to visit an unsafe page.

Avoid opening any unknown and unwanted emails on your computer. Refrain from clicking on the links that are mentioned within such emails unless it's from a reliable source.

Do not download or operate applications or programs on your system from sources that are not trusted.

Do not click on pop-up windows that assure free products, these normally lead to financial losses and an increase in your computer's virus load.

Examples of Trojan Horse Virus Attacks

There have been many infamous trojan attacks that have infected computers o a large scale to collect user data. Some of the most popular examples are,

Andromeda - This is a modular trojan used by hackers to install malware payloads and banking trojans. It is disguised under plugins like HTMLformgrabber, keyloggers, rootkit, etc. This trojan was fixed by CrowdStrike. They used PowerShell to remove the malware without affecting the user.

Tiny Banker - Tiny Banker is a trojan that hackers use to steal the financial data of users. This trojan affected over 20 banks in the US.

Rakhni Trojan - This is a ransomware trojan that mines cryptocurrency from infected devices. So if your device is hit with the Rakhni Trojan, then it will mine cryptocurrency from your computer. You will see reduced performance and high power usage.

What is a Trojan Horse - Conclusion

The Trojan Horse has been there since the existence of computers and it gets stronger and stronger as more and more bad people work on it for their reasons.

As innocent users, all we can do is follow safe digital practices to avoid falling into its trap.

Also, make sure you always have a good antivirus so that your computer can stay protected from other dangerous viruses and malware too.

Is a Trojan horse a virus or malware?

Although technically wrong, a Trojan horse may sometimes be referred to as a Trojan horse virus. A Trojan horse cannot replicate itself or spread without the help of an end user, unlike a computer virus. To mislead the end user into running the Trojan, the attackers must employ social engineering strategies.

Since there are so many different varieties of Trojan horses, the phrase can be used as a catch-all for malware distribution. The Trojan can operate in a variety of ways, sometimes acting as standalone malware, other times acting as a tool for other tasks including delivering payloads, making the system vulnerable to attacks, or communicating with the attacker, depending on the attacker's aim and the application's structure.

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