A Trojan horse, commonly known as a Trojan, is a malicious code which appears to be legitimate but takes control of your computer completely. It is designed to steal, damage, disrupt data and inflict harm to your network.

A Trojan works like a bona fide application to trick the user and the system. It deceives you into downloading the malware file. Once installed, the Trojan performs the action it was made for.

While the names ‘virus’ and ‘Trojan horse virus’ might be used interchangeably, they aren’t the same. A virus can replicate themselves, while a Trojan or a Trojan horse (and not Trojan horse virus) cannot replicate itself, but it can still cause destruction.

How does the Trojan work?
Trojans have been given the name from the story of the hollow wooden horse that the Greeks hid inside during the Trojan War. The Trojan was then given to the people of Troy as a gift, which the walled city accepted wholeheartedly. This allowed the Greeks to come out and attack the sleeping Trojans.

You may have received an email from a known source but when you click on the legit attachment, it turns out you have been hacked. The email is from a hacker and the attachment that was downloaded was infected. When the file is executed, the malware spreads into the other files damaging the computer. The files are designed to do different things.

Trojans create a problem for computers and your mobile devices like cell phones and tablets. Trojan comes with a legitimate program but it is a fake version of the app and is loaded with malware. Hackers place them on unofficial app market for unsuspecting users. These apps steal information from your various devices and generate revenue by sending premium SMS.

Types of Trojans
Listed below are some common types of Trojans you may have heard about:

• Backdoor Trojan
  This Trojan creates a “backdoor” to your computer allowing the hacker to access your computer. A third party can download/steal your data, or he/she can upload multiple malware onto your device.
• Distributed Denial of Service (DDoS) attack Trojan
  This Trojan takes down a complete network by overwhelming it with traffic which is coming from the infected computer and others.
• Downloader Trojan
  The already infected computer is attacked by this Trojan. It downloads and installs new malware programs including Trojans and adware.
• Fake AV Trojan
  This Trojan acts like an antivirus and demands money to detect and remove threats which are real or fake.
• Game-thief Trojan
  The online gamers break through your computer through a Trojan to steal account information.
• Infostealer Trojan
  This Trojan steals data from an infected computer.
• Mailfinder Trojan
  This one steals email addresses on your device.
• Ransom Trojan
  This Trojan damages your computer and seeks a ransom to undo the same.
• Emotet banking Trojan
  The activity of this Trojan increased after 2017. The detection also increased by over 200%. This virus steals financial information by injecting a computer code into an infected device which siphons financial data from the same.
• Rakhni Trojan
  This has been in existence since 2013. It delivers ransomware or a crypto-jacker allowing the hacker to mine cryptocurrency to infected computers.
• ZeuS/Zbot
  This Trojan was released in 2011. It uses keystroke logging that is it records your keystrokes when you log into your bank account. It steals your credentials and subsequently, your money too.
• Switcher Trojan
  This type of Trojan affects Android devices. It infects the user devices to attack the routers on wireless networks. Hackers then redirect traffic on Wi-Fi-connected devices using it for criminal activities.

If attacked by Trojan malware, it is important to be careful. Make sure you install a reliable version of an antivirus in your systems and devices.