In recent years, the actors of terrorism quickly learned how to adapt to the new communication and media environment. From face-to-face communication, localized propaganda, and direct recruitments methods, terrorist cells and organizations started moving their activities to online forums, social networks, and social media. The impact is huge and widespread: not only has their primary reach extended, but also, thanks to the overall globalization of communication methods, they are being given secondary "advertisement" through exposure in world media. This is becoming more than evident in the case of ISIS, whose reach and communication methods are unprecedented. This paper concentrates not only on ISIS, however, as it introduces when and how terrorism started turning viral and what particular forms this communication, propaganda as well as recruitment shift takes, together with what primary and what secondary threats it poses. Moreover, emphasis is put on both the technical aspects of the aforementioned changes as well as on the analysis of the new means of communication as such, namely on its linguistic, psychological, imagery, and security content. The outcome of the paper is the identification of the methods and analysis of the current state of affairs in terrorist communication, together with overall evaluation of their contemporary recruitment and propaganda practices.