A Trojan horse program is a malware that is not capable of automatically spreading to other systems. Trojans are usually downloaded from the Internet and installed by unsuspecting users.
Trojans typically carry payloads or other malicious actions that can range from the mildly annoying to the irreparably destructive. They may also modify system settings to automatically start. Restoring affected systems may require procedures other than scanning with an antivirus program.
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