A botnet is a set of compromised computers, or bot clients, running malicious software that enables a “botherder” or “botmaster” to control these computers remotely. A botherder or botmaster can design a botnet to perform certain actions, such as information stealing or launching a denial of service, and issues commands to the bot clients from a command and control (C2) server. Since mobile networks are now well integrated with the Internet, botnets are beginning to migrate to mobile devices, as seen with Ikee.B.
Zeus (also known as Zbot, PRG, Wsnpoem, Gorhax and Kneber) is a Trojan horse that steals banking information bykeystroke logging. Zeus is spread mainly through drive-by downloads and phishing schemes. First identified in July 2007 when it was used to steal information from the United States Department of Transportation, it became more widespread in March 2009. In June 2009, security company Prevx discovered that Zeus had compromised over 74,000 FTP accounts on websites of such companies as the Bank of America, NASA, Monster, ABC, Oracle, Cisco, Amazon, and BusinessWeek.