Botnet

A botnet (a contraction of the term “Bot Networks”) is made up of a vast number of compromised computers that have been infected with malicious code, and can be remotely-controlled through commands sent via the Internet. Hundreds or thousands of these infected computers can operate in concert to disrupt or block Internet traffic for targeted victims, harvest [information]], or to distribute spam, viruses, or other malicious code (called collectively "Botnet code"). Botnets are becoming a major tool for cybercrime, partly because they can be designed to very effectively disrupt targeted computer systems in different ways, and because a malicious user, without possessing strong technical skills, can initiate these disruptive effects in cyberspace by simply renting botnet services from a cybercriminal. Botnets have been described as the “Swiss Army knives of the underground economy” because they are so versatile.