What is a Trojan Malware? The Ultimate Guide

In computer security, a Trojan horse, or Trojan, is a malware that masquerades as benign software to get access to your system. A Trojan is a malicious program that may destroy, disrupt, steal, or otherwise inflict harm on your computer system or data.

A Trojan pretends to be a legitimate program or file to deceive its target. Its purpose is to trick you into downloading and running malicious software on your computer or mobile device. Once a Trojan is implanted, it may carry out its intended function.

There is no such thing as a Trojan or Trojan horse virus, yet both names are common. Viruses are autonomous agents that can carry out their instructions and reproduce. As a Trojan, you can't. Trojans can only be activated after the user clicks the "Run" button. Despite this, it's not uncommon for people to confuse Trojan malware with Trjan viruses.

Whether you refer to it as Trojan malware or a Trojan virus, understanding this intruder and taking precautions against it is prudent.

How Exactly do Trojans Function?

Here is a sample of Trojan malware that demonstrates this concept.

You may be tempted to open the attached file if the email appears to be from a trusted contact. Unfortunately, you've been duped. If you downloaded and opened the file attached to the malicious email, you have unwittingly let the cybercriminal install malware on your computer.

Infectious code can replicate itself throughout your system when you run the application.

How? This varies. Trojans may be programmed to do a variety of tasks. And you'll likely be wishing they weren't performing any of them on your gadget.

Is it a Trojan Horse Malware or a Virus?

While not technically viruses, Trojans are nevertheless malicious software. There is no such thing as a "Trojan virus" or "Trojan horse virus," despite common usage. It's because viruses and Trojans attack their victims in very different ways. In contrast to viruses, Trojans cannot spread without being installed on a computer.

That's what sets viruses apart from Trojan horse malware. Malware comes in many forms, including viruses and Trojans.

Backdoor Trojans

The purpose of backdoor Trojans is to provide cybercriminals with a covert entry point into your system. This vulnerability may be exploited in various ways, including for data collection and monitoring, malware distribution, and botnet recruitment.

Banking Trojans

Trojan banking software secretly infiltrates your system to steal your banking details. Hackers commonly use them to get access to a target's financial accounts. The Zeus Trojan was a particularly notorious financial Trojan.

DDoS Trojans

DDoS Trojans aim to recruit your device into a botnet, a group of computers controlled by one hacker, or "bot herder," remotely. By utilizing the botnet, they will launch DDoS assaults that will bring down several other online resources.

Dropper or Downloader Trojans

The term "blended threat" refers to a three-part malware package that often includes a dropper, a loader, and further malware (often a rootkit). A hacker can gain access to your device when the dropper Trojan infects it and prepares the way for the loader, which installs a rootkit. Various downloader Trojans will install different forms of malware.

Exploit Trojans

These malicious Trojans infect your device with exploits, which are software techniques that exploit a known security hole in your system's software or hardware. In computer security, zero-day exploits are used to take advantage of flaws not found by anybody except the person developing the exploit.

Fake Antivirus Trojans

It is a form of malicious scareware, phoney antivirus. When a Trojan claims to have detected viruses or other malware on your device, it will usually try to sell you fake or harmful protection software. Whenever you make a payment, the Trojan's developer gains access to your financial information.

Gaming Trojans

Gaming Trojans are known to steal login information from online gamers. Hackers can use these to get access to famous gamers' accounts or steal expensive virtual goods.

Infostealer Trojans

The purpose of info stealer Trojans is to steal sensitive data. They will search your device for private information and relay it back to the hacker who attacked you. Fraud and identity theft can be committed using this information by cybercriminals.

Instant Message Trojans

IM Trojans infiltrate your device using its instant messaging (IM) software, stealing your passwords and accessing your address book. Newer encrypted IM programs like WhatsApp and Signal are safer than older services like Skype and MSN Messenger, although spyware is always improving.

Mailfinder Trojans

Mailfinder Trojans, while less of a threat now that most people use webmail services like Gmail, nevertheless target email programs like Microsoft Office to harvest email addresses. Any stolen email addresses can be used in further phishing or spam campaigns.

Ransomware Trojans

Ransomware is software that encrypts your data and refuses to unlock it unless you pay a ransom. Tricking victims into launching the ransomware is a common tactic used by ransomware Trojans.

SMS Trojan

SMS Mobile devices, often Android ones, can be infected by Trojans that intercept incoming and outgoing communications or cause them to be sent to the cybercriminal's premium service account at the victim's expense.

Attacks Utilizing Trojan Horses

Trojan horse malware has historically been responsible for some of the most devastating assaults. Take a look at some of the most famous Trojans in history.


The first known use of the ZeuS Trojan was in a 2007 data theft attempt against the United States Department of Transportation. ZeuS is primarily a banking Trojan that steals financial data using one of two browser-based methods.

The Trojan is keylogging, which records your keystrokes as you type them into your browser.

ZeuS can steal your login information from a website by intercepting your form submissions.

Millions of machines were infected with ZeuS after it was spread by phishing emails and automated drive-by downloads on infected websites; this is why it was used to construct Gameover ZeuS, one of the most infamous botnets in history.


First spotted in 2014, Emotet originated as a financial Trojan. But as fraudsters began exploiting it to deliver other malware instead, Emotet caused big ripples in cybersecurity.

Routinely acknowledged as one of the most devastating malware strains ever produced, Emotet targeted corporate and individual victims equally through large spam and phishing operations. he software was used to construct many botnets rented out on a malware-as-a-service (MaaS) basis to other ambitious cyber criminals.

Emotet was eventually disrupted in 2021 by a concerted worldwide law enforcement effort.


Trojans aren't only for Windows – Shedun is an Android adware Trojan horse that repackages real Android apps with fraudulent adware before rehosting them on third-party download sites. You receive the adware when you install the software from one of these sites.

Once you install the infected program, you're inundated with adverts that generate income for the attacker. Removing the infection from your Android handset is exceedingly tough, and most victims choose to buy new devices instead. By 2016, Shedun was estimated to have infected over 10 million Android devices.

Updated on: 02-Jan-2023


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