Which type of malware is defined by its ability to propagate without user action?

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

Answer: (A)

Propagating without user action means the malware can copy itself to other systems on its own, using network connections or other automated methods. That self-spreading behavior is what defines a worm. A worm is a standalone program that seeks out vulnerable systems, copies itself, and runs on those systems without someone opening a file or clicking a link. This automatic spread through networks, email, or other service channels is the hallmark that sets worms apart from other malware types. Viruses, by contrast, typically require a user to execute or open an infected file for replication. Trojans rely on tricking users into installing or running them, rather than spreading autonomously. Adware focuses on displaying ads or collecting data and isn’t about propagating itself across machines.