Malware - Infectious Malware: Viruses and Worms

Infectious Malware: Viruses and Worms

The best-known types of malware, viruses and worms, are known for the manner in which they spread, rather than any specific types of behavior. The term computer virus is used for a program that has infected some executable software and, when run, causes the virus to spread to other executables. On the other hand, a worm is a program that actively transmits itself over a network to infect other computers. These definitions lead to the observation that a virus requires user intervention to spread, whereas a worm spreads itself automatically.

Using this distinction, infections transmitted by email or Microsoft Word documents, which rely on the recipient opening a file or email to infect the system, would be classified as viruses rather than worms. Some writers in the trade and popular press misunderstand this distinction and use the terms interchangeably.