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Trojans are the most common type of malware. Unlike viruses, trojans can’t spread on their own – they rely on you to run them on your PC by mistake, or visit a hacked or malicious webpage.
A trojan might use the same file name as a real or legitimate app - so you might accidentally download a trojan, thinking you are downloading something else.
They are called trojans because they are like the mythological wooden Trojan Horse that was used to sneak into the ancient city of Troy.
They are often installed with other types of malware, so it's unlikely you'll only get infected with one trojan and nothing else.
How did I get infected with a trojan?
Trojans can't spread by themselves, which means you either downloaded it, thinking it was something else, or another malware downloaded and installed it onto your PC.
Also see the following for more help:
What do trojans do?
Trojans can come in many different varieties, but generally they do the following on your PC:
- Download and install other malware, such as viruses or worms.
- Use your PC for click fraud.
- Record your keystrokes and the sites you visit.
- Send information about your PC to a malicious hacker including your passwords, login details for websites, and browsing history.
- Give a malicious hacker control over your PC.
How do I remove a trojan?
Use the following free Microsoft software to detect and remove it:
- Windows Defender Antivirus for Windows 10 and Windows 8.1, or Microsoft Security Essentials for Windows 7 and Windows Vista
- Microsoft Safety Scanner
You should also run a full scan. A full scan might find other, hidden malware. If you still can't remove it, visit our advanced troubleshooting page for more help.