The best-known types of malware, viruses and worms, are known for the manner in which they spread, rather than any other particular behavior. The term computer virus is used for a program that has infected some executable software and that causes that software, when run, to spread the virus to other executable software. Viruses may also contain a payload that performs other actions, often malicious. A worm, on the other hand, is a program that actively transmits itself over a network to infect other computers. It too may carry a payload.
These definitions lead to the observation that a virus requires user intervention to spread, whereas a worm spreads 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 appear to misunderstand this distinction, and use the terms interchangeably.
http://en.wikipedia.org/wiki/Malware |