A Trojan attack involves a type of malicious code or software that appears legitimate but can take control of your computer. Trojans often disguise themselves as legitimate software or are hidden within legitimate software that has been tampered with. They differ from viruses and worms because they do not replicate. However, once activated, Trojans can enable cyber-criminals to spy on you, steal your sensitive data, and gain backdoor access to your system. This can include unauthorized actions such as deleting files, monitoring user activities, or installing additional malicious software.