Suppose that one day you get an e-mail from one of your friends suggesting you download and install a new game she found online. You download, install, and play the game. Without your knowledge, the game forwards a recommendation to download and install the game to all of your e-mail contacts. Without any outward sign, each instance of the game is part of a malicious attempt to flood a government website so that it crashes. What type of virus is on your computer?
a companion virus
a polymorphic virus
a boot sector virus
a sharing virus