Which type of malware executes destructive actions when the user opens or accesses it?

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

Answer: (A)

When malware activates only after the user opens or accesses the file, it reflects how a virus behaves. A virus attaches to a host file or program and stays dormant until that program is opened or executed. Once activated, it can perform destructive actions—such as deleting or corrupting data—and can spread to other files or systems as those infected programs are shared. This makes it distinct from a worm, which propagates across networks without requiring user action to open anything, and from a Trojan Horse, which disguises itself as legitimate software and executes malicious actions when run but doesn’t inherently self-replicate. DDoS is an attack method rather than a malware type. So the description best matches a virus.