Peer to Peer Security

How do popular file sharing programs such as Limewire or Bittorrent work? Your computer does not communicate with a central server like it would if you were visiting a website or ftp server. Rather, you communicate with computers that are part of the network. This concept is called peer to peer or p2p. When a user searches for a certain file from the network, the request is sent out to computers that are close to the user geographically. These computers are called nodes. These nodes receive the request and check if the file is a part of their shared files. If it is not, then they send the request to other computers close to them, which are also nodes. Once a file is found, it is echoed back from computer to computer until it reaches the original requesting computer.

Unfortunately, certain security issues arise when searches are performed this way. The main issue is that the request is sent across multiple computers and these nodes are responsible for deciding where to send the request. A malicious programmer can easily create a piece of malicious code that allows their computer to become a part a node within the network. When a request comes to this infected computer, rather than sending the request to other nodes it echoes that the file has been found on the computer. Then when the user downloads the file it is actually a virus, trojan, worm or other malicious piece of software. Another variation of this is that the infected node directs the user to a server which contains malicious software and the software is downloaded from there.