What is a Trojan horse in cybersecurity?

D2 ยท Threats  ยท  CompTIA Security+ SY0-701
A Trojan horse (Trojan) is malware that disguises itself as legitimate, useful software to trick users into installing it. Unlike viruses, Trojans don't self-replicate โ€” they rely on social engineering for distribution.

Types: RAT (Remote Access Trojan) โ€” gives attacker remote control; banking Trojan โ€” steals financial credentials; downloader Trojan โ€” downloads additional malware; backdoor Trojan โ€” creates persistent access.

Common delivery: email attachments, fake software downloads, pirated software.
Trojans โ‰  viruses. Viruses self-replicate; Trojans need user action to install. RATs are particularly dangerous โ€” they provide full interactive access. Defenses: email filtering, application allowlisting, user education. Check software signatures before installing.
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