Which term describes harmful software disguised as a normal file?

• A. Trojan Horse
• B. Virus
• C. Worm
• D. Adware

Answer: (A)

Harmful software that hides inside a normal-looking file is a Trojan Horse. It works by tricking you into thinking the file is safe, so you open or run it, and then the malware activates. The deception relies on social engineering rather than the program self-replicating or spreading on its own. This distinguishes it from a virus, which attaches to other programs and spreads when they are executed, and from a worm, which propagates across networks without user action. Adware, on the other hand, mainly presents unwanted advertisements rather than disguising itself as a legitimate file to lure you into installing it. So, a Trojan Horse is the best fit for harmful software that is disguised as something ordinary.