ABSTRACT
This chapter focuses on the emerging and predominant threat of botnets. The botnet formation starts by recruiting as many vulnerable machines as possible to become part of a botnet. Understanding botnets and their operational aspects require us to investigate different bots to reveal their malicious intents. The size of a botnet represents an important factor of the intensity and the widespread of cyberattacks. The ambiguity in specifying a botnet size is due to several issues that complicate the task of computing the number of compromised machines in a botnet. Socialbots are autonomous software programs that target online social networks such as Facebook and Twitter. The enormous growth of the Internet and its expansion has contributed greatly in the development of new generation of botnets that leverage the vulnerabilities of new protocols, applications, and devices that composes the Internet.
