A malicious program that is disguised as legitimate software that may look useful or interesting to an unsuspecting user, but are actually harmful when executed. Trojan horses are almost always designed to do various harmful things, such as:
- corrupting files
- erasing or overwriting data
- encrypting files
- spreading other malware, such as viruses
- spying on the user of a computer and covertly reporting data such as browsing habits to other people
- logging keystrokes to steal information such as passwords and credit card numbers (also known as a keylogging)
- uploading and downloading files
- setting up networks of zombie computers in order to send spam
- making screenshots
