What is a Trojan?

The Greeks could not penetrate the walls of Troy during the Trojan War until they decided to do something a little differently. They build a large wooden horse, hid an elite fighting force within it, and left it at the gates of Troy. The Trojans brought the horse inside their walls thinking it was a trophy built for them. Little did they know they had just been infiltrated from within as a result of their own action.


A Trojan Horse, or just Trojan, is a software program that installs onto your machine without your consent, often disguising itself as legitimate software. Unlike a virus, a trojan cannot copy itself nor infect files. Trojans are used by cyber criminals to gain backdoors to your machine to steal personal data or load malicious software such as ransomware.

The trojan is one of the first types of spyware and is the most popular type still in use today. Trojans make up a large amount of our malware research here at SUPERAntiSpyware HQ and detections of trojans make up quite a bit of our definition releases.

There are many different types of trojans that can infect your system.

  • Trojan Banker: This type of trojan is made to obtain financial information stored on your system that will grant access to your bank accounts, credit accounts, and other sources of financial information.
  • Trojan Downloader: This type of trojan may end up on your system after you download a file from an unverified source.
  • Trojan Dropper: The goal of this type of trojan is to allow the hacker to "drop" more lethal malware onto your system, such as other trojans or ransomware.
  • Trojan Injector: A type of trojan that injects itself into other running processes. This method is a way for hackers to hide from the average user as they will not see anything out of the ordinary.

Return to the Malware Glossary page.