Virus vs. Worm: How Common Malware Types Differ

Summary

An introductory guide distinguishes viruses, worms, trojans, ransomware, rootkits and fileless malware, explains how they spread or hide, and notes how misidentifying a worm can misdirect incident response. It also recommends backups, updates and disabling macros.

Key points

• Viruses attach to files and need user action to spread; worms self-replicate across networks without human interaction.
• Trojans disguise themselves as legitimate software and can open a backdoor, but do not self-replicate.
• Ransomware encrypts files and demands payment; the article recommends backups and notes that payment does not guarantee recovery.
• The article describes rootkits as hiding within the operating system and fileless malware as running in memory using trusted tools such as PowerShell.
• Misidentifying a worm as a virus can lead responders to focus on infected files while overlooking network propagation.
• Suggested basic defenses include maintaining backups, updating browsers and operating systems, and disabling macros by default.