The original Trojan was, indeed, a mythological wooden horse that turned out to be something entirely different than the gift from the gods the mythic Trojans thought it to be. In the realm of cyber security the term Trojan denotes a very specific type of malware with specific boundaries.
Strictly speaking, Trojans are defined as malicious programs that perform actions on a computer that have not been authorized by the user.
Those actions might include:
By definition a Trojan does not self-replicate. There are, however, hybrid Trojan/viruses that do.
Trojans are classified by the types of actions they can perform. And so, without further ado, we bring you our top 14 types of Trojans.
A backdoor Trojan gives the hacker remote control over the infected computer. They can be used to pull together a number of separate, infected machines to form a botnet or zombie network that can be put to nefarious use.
An exploit Trojan is a program that contains code that takes advantage of a known vulnerability within a piece of software running on the infected computer.
A rootkit Trojan conceals objects and activities on the infected computer. They are primarily used to avoid being detected by security software, buying time to take further advantage of the hack.
A Trojan-banker is specifically designed to steal your financial data – bank logins, credit card and trust account information.
A Trojan DDoS has one purpose. It sends a huge number of requests to single page in a single web domain such that the amount of traffic overruns the website servers, shutting the site down.
A Trojan-downloader does just what it says – is downloads and installs new versions of malware, including adware and new Trojans.
A Trojan-dropper is a more sophisticated downloader that more incrementally installs new Trojans and viruses in such a way as to make detection by security software less likely.
A Trojan-Fake AV is a program that simulates the activity of antivirus software. The are designed to extort money from the target in return for detection and removal of threats – even though those threats are fictitious.
A Trojan-Game Thief steals user information from online gamers.
A Trojan-IM does…you guessed it! It steals your logins and passwords from instant messaging platforms like WeChat, Skype, QQ and more.
A Trojan-Ransom modifies your computer to the point to where you can no longer use it or access certain data. In return for paying a cash ransom it may (or may not) restore the victim’s access to their data.
A Trojan-SMS is relatively simple and can be very expensive. It invades your cell phone and surreptitiously sends numerous fee-based SMS messages, which end up on your cellular phone bill.
A Trojan-Spy is aptly named in that it spies and logs your activity doing everything from copying every keyboard button pushed to taking screenshots and then sending that data out to a hacker or hacker network.
And finally, there are Trojan-Mailfinders. They, as one might surmise, harvest email addresses from your computer which are then sold to email marketing and spam companies.
