P2P Worms spread via peer-to-peer file sharing networks (such as Kazaa, Grokster, EDonkey, FastTrack, Gnutella, etc.).

Most of these worms work in a relative simple way: in order to get onto a P2P network, all the worm has to do is copy itself to the file sharing directory, which is usually on a local machine. The P2P network does the rest: when a file search is conducted, it informs remote users of the file and provides services making it possible to download the file from the infected computer.

There are also more complex P2P-Worms that imitate the network protocol of a specific file sharing system and responds positively to search queries; a copy of the P2P-Worm is offered as a match.