Over the next few weeks we are going to publish blogs on different types of malware so when you see a reference to Trojan’s, ransomware or rootkits, for instance, you’ll have a better understanding of what each term means.

Trojan comes from the Greek classical story about the Trojan War.  Using subterfuge the Greeks entered the independent city of Troy after a fruitless 10-year siege. They constructed a huge wooden horse and hid a force of men inside to take over the city.

As such a Trojan is a type of malware that is often disguised as a normal file like a Word document. Trojans are typically used by cyber-thieves and hackers trying to gain access to a users' computer.

People are typically tricked by some form of social engineering such as an email with an infected Word attachment.  By opening the document the Trojan is loaded onto the victim’s computer. Once activated, Trojans can enable cyber-criminals to spy on you, steal sensitive data and gain backdoor access to your system.

While a Trojan performs the same function in that it secretly downloads onto a computer its actions can vary depending on what cyber crooks have programmed it to do. These actions are wide and varied but some of the most common are listed below.
  • Backdoor
A backdoor Trojan gives hackers remote control over an infected computer. They can then do pretty much anything they want to including sending and deleting files, displaying data and rebooting the computer. However, more commonly Backdoor Trojans are often used to create a botnet or zombie network that can be used for malicious purposes.
  • Exploits
Trojan exploits are malicious code that takes advantage of a vulnerability within application software that’s running on your computer. For instance, hackers might discover a flaw in a popular software program and then launch a Trojan exploit to take advantage of it.
  • Trojan-Banker
Trojan-Banker programs are designed to steal your account data for online banking systems and credit or debit cards or other personal information. They essentially log your keyboard strokes when you visit a banking website they have been programmed to identify.

BullGuard protects your computer from viruses and hackers

  • Rootkit
Trojan rootkits are designed to conceal certain objects or activities in your computer’s system. Often their main purpose is to prevent malicious programs being detected such as spyware. The aim is to extend the length of time in which malware programs can run on an infected computer.
  • Trojan DDoS
These programs carry out denial of service attacks against a targeted web address. They are designed to infect thousands of computers and then using these infected computers send so many requests to the targeted web sites that they crash under the overwhelming weight of the requests.
  • Trojan Downloader 
Trojan-Downloaders download and install new versions of malicious programs onto your computer including other Trojans and adware.
  • Trojan Fake antivirus
If your computer has ever been taken over by pop-up ads that blaze out warning messages that you have been infected with a virus and you need to buy some antivirus then it’s likely a Trojan Fake antivirus has got into your computer. These Trojans are designed to extort money from you even though the threats that they report are actually non-existent.
  • Trojan SMS
These Trojans sneak onto your mobile phone as the result of clicking on a malicious link or downloading an infected app, and then send text messages to premium rate phone numbers for which you pay.
There are other actions that Trojans carry out but these are the main ones that are widely in use. So how do you defend against them? 

Use good security software such as BullGuard Internet Security which was recently awarded a coveted Gold Malware Protection from AV-Comparatives, an independent testing lab. The honour was bestowed by AV-Comparatives for BullGuard’s next-generation layered defence system which defeats all types of malware including Trojans.