Online social networks: The overt and covert communication channels for terrorists and beyond

The over 1 billion active users of online social networks are evidence of the enormous growth of these technologies. Although, the majority of social network users use such services for ordinary social interactions, a very small number may possibly be misusing them for terrorism. In this paper, we discuss how terrorists may be using online social networks not only to recruit new members to a terrorist organization but to maintain the loyalty of their existing sympathizers; plan attacks and share information about them; train recruits for specific attacks; raise funds for their causes; propagate fear amongst the enemy population; and engage in counterintelligence to uncover undercover agents.We also discuss several mechanisms that can be used to detect terrorists using the overt and covert communication channels on online social networks. Moreover, we show that the keyword-only flagging mechanism used by US Department of Homeland Security to detect terrorists, is potentially effective, but certainly produces a large number of false positives, making it possibly less efficient in practice.