...and a far less imaginative type which simply purchases every pr0n pay-per-view for the next 6 months for you.
Ahem, yep, I know that virus. It keeps reinfecting my cable box. :) Wait, what do you mean, you were only describing an hypothetical virus? Oh god, now I'm so embarressed.
Seriously though, we were discussing viruses in #kuro5hin, and came up with some pretty neat virus ideas ourselves. The one I was fond of (and thought of) was a virus that created a pseudo-gnutella network, scanned your hard disks for mp3s, linked up to the pseudo-gnutella network (using the host that infected it as an entry point), communicated with the other virii, determined what mp3s you'd probably want based on the mp3s you have (using what other people have in their collections, and how closely they match yours), and then take a small, unobtrusive portion of your bandwidth and use a set percentage of your hard drive based on free space left and how much of your hard drive is devoted to mp3s already, and then starts downloading. Heck, you could do it that it only downloads when a download is already going, so the additional network activity isn't noticeable by most people, who'd figure a 10 - 25% drop in speed would be because of the slow internet. Just an interesting proof-of-concept virus. Sure, it might be a tad big, for all it has to do, but it only has to infect a small loader, that then grab data from the infecting host to get the rest of the program... Only problem is that zonealarm or tinyfirewall would catch it in a flash. :( Hmmm, OTOH, I've never checked out either ZA or Tiny, maybe there is a way for the virus to modify the programs to allow it to pass unmolested. Of course, that still leaves other personal firewall software that needs to be altered, but if you get the common ones, it helps prevent detection by most.
Then again, there is my old standby of a virus that replaces windows solitaire to make a 51 card deck + one spare.
I'm sorry, but virus coders who only code distructive virii have no imagination. :) Any idiot can (and many idiots do) code poorly designed virii which tend to destroy windows networking (and thus give themselves away), or start destroying system files (thus killing off their host). Unfortunately, unlike the real world, any virus that kills off its host actually hinders the spreading of itself. A virus in the real world might gain an advantage by so crippling the host's resources that the host cannot defend itself and can thus allow the virus to distribute more copies of itself, but the closest thing a computer virus can do is a blitzkreig attack, using all system resources as soon as its infected the host, which gives the virus away, but might allow it to spread far before most anti-virus software is updated to identify it. A delayed kill only means that the virus killed off a sucessful host that probably had no clue that it was there.