Are there any open source viruses?
A question on programmers.se got me wondering: has anybody released an open source virus? Of course I'm just wondering out of sheer curiosity of what a virus's source code might look like. A quick google search shows that there are plenty of open source antivirus programs, but I didn't see any open source viruses.
Answer
What do you mean by "open source"? I'm sure none of them are copyrighted and there are enough sources on the internet. You can try VX Heavens for example.
EDIT: As response to @blake305:
First, virus is a computer program that is able to "reproduce" itself. It has nothing to do with freezing computer. Here is some theory:
In the past there was something called "the scene". There were many known virus writers who wrote viruses for fun and as competition (for example, the shortest file infector), so each such virus contained a signature. Obviosly, you had to present it (and usually together with the source code) for the contest. As you can see, a classic virus have three different parts:
1) Reproduction (that's why it's virus)
2) Self-protection (usually all kind of passive "stealth" techniques, encryption, polymorphism, and so on)
3) Payload (destructive code. Usually a "state of the art" virus don't have it. Usually a distractive payload is added by others, who are not so good in writing the first two modules).
While the payload is the most simple part, it practically makes viruses illigal. The second part is very difficult to implement, so it actually became the most important challenge for virus writers. I would also recommend some articles written by Z0mbie.
Finally, most virus sources you could find on that site are just outdated, so they are useful only for "academical" purposes.