Definition
A Trojan horse, often shortened to Trojan, is a type of malware that disguises itself as legitimate software to trick users into installing it. Once executed, it can perform malicious actions in the background without the user's knowledge or consent. Trojans are designed to gain unauthorized access, steal sensitive data, or disrupt system operations. For instance, a user might download what appears to be a free game, but it secretly contains a Trojan that creates a backdoor for attackers. Unlike viruses that self replicate, Trojans do not spread on their own but rely on social engineering to be delivered. Understanding Trojans is crucial for cybersecurity professionals and is covered in certifications like CompTIA Security+ and CISSP.