How are computer viruses made?
There are multiple types of viruses that exist as of (year 2005) today. Corrections about answers made by others answering this question: -A virus does not have to copy or self replicate itself. -A virus does not have to cause harm or annoy or anything else. There are some virii that do not replicate and have to be installed manually. (logic bombs for example) There are a few virii that actually patch certain security vulnerabilities and then delete themselves. Here is more details about virus types/characteristics: root kit (lately gotten really popular although it has been around since the unix days) Trojan (most common – self contained program whose job is to infiltrate) Worm (getting more common – network aware, replicates itself ceaselessly and may or may not have a payload) Polymorphic (changes form and characteristics to avoid detection) Boot sector infector (no longer common – more “popular” in the 70s-80s) Multipartite (not too common as it is harder to build – comprised of 2
