A Trojan horse, or Trojan, is a type of malicious code or software that looks legitimate but can take control of your computer. A Trojan is designed to damage, disrupt, steal, or in general, inflict some other harmful action on your data or network. A Trojan acts like a bona fide application or file to trick you. It seeks to deceive you into loading and executing the malware on your device. Once installed, a Trojan can perform the action it was designed for.
A Trojan is sometimes called a Trojan virus or a Trojan horse virus, but that’s a misnomer. Viruses can execute and replicate themselves. A Trojan cannot. A user has to execute Trojans. Even so, Trojan malware and Trojan virus are often used interchangeably.
Whether you prefer calling it Trojan malware or a Trojan virus, it’s smart to know how this infiltrator works and what you can do to keep your devices safe.
How Do Trojans Work?
Here’s a Trojan malware example to show how it works.
You might think you’ve received an email from someone you know and click on what looks like a legitimate attachment. But you’ve been fooled. The email is from a cybercriminal, and the file you clicked on — and downloaded and opened — has gone on to install malware on your device.
When you execute the program, the malware can spread to other files and damage your computer.
How? It varies. Trojans are designed to do different things. But you’ll probably wish they weren’t doing any of them on your device.
Types Of Trojan Malware
Here’s a look at some of the most common types of Trojan malware, including their names and what they do on your computer:
Backdoor Trojan – This Trojan can create a “backdoor” on your computer. It lets an attacker access your computer and control it. Your data can be downloaded by a third party and stolen. Or more malware can be uploaded to your device.
Distributed Denial of Service (DDoS) Attack Trojan – This Trojan performs DDoS attacks. The idea is to take down a network by flooding it with traffic. That traffic comes from your infected computer and others.
Downloader Trojan – This Trojan targets your already-infected computer. It downloads and installs new versions of malicious programs. These can include Trojans and adware.
Fake AV Trojan – This Trojan behaves like antivirus software, but demands money from you to detect and remove threats, whether they’re real or fake.
Game-Thief Trojan – The losers here may be online gamers. This Trojan seeks to steal their account information.
Infostealer Trojan – As it sounds, this Trojan is after data on your infected computer.
Mailfinder Trojan – This Trojan seeks to steal the email addresses you’ve accumulated on your device.
Ransom Trojan – This Trojan seeks a ransom to undo damage it has done to your computer. This can include blocking your data or impairing your computer’s performance.
Remote Access Trojan – This Trojan can give an attacker full control over your computer via a remote network connection. Its uses include stealing your information or spying on you.
Rootkit Trojan – A rootkit aims to hide or obscure an object on your infected computer. The idea? To extend the time a malicious program runs on your device.
SMS Trojan – This type of Trojan infects your mobile device and can send and intercept text messages. Texts to premium-rate numbers can drive up your phone costs.
Trojan Banker – This Trojan takes aim at your financial accounts. It’s designed to steal your account information for all the things you do online. That includes banking, credit card, and bill pay data.
Trojan IM – This Trojan targets instant messaging. It steals your logins and passwords on IM platforms.