Smartphones are now targets of malicious viruses. Furthermore, the increasing 'connectedness' of smartphones has resulted in new delivery vectors for malicious viruses, including proximity-, social- and other technology-based methods. In fact, Cabir and CommWarrior are two viruses-observed in the wild-that spread, at least in part, using proximity-based techniques (line-of-sight bluetooth radio). In this paper, we propose and evaluate SI 1I2S a competition model that describes the spread of two mutually exclusive viruses across heterogeneous composite networks, one static (social connections) and one dynamic (mobility pattern). To approximate dynamic network behavior, we use classic mobility models from ad hoc networking, e.g., Random Waypoint, Random Walk and Levy Flight. We analyze our model using techniques from dynamic systems and find that the first eigenvalue of the system matrices λs1, λs2 of the two networks (static and dynamic networks) appropriately captures the competitive interplay between two viruses and effectively predicts the competition's 'winner', which provides a feasible way to defend against smartphone viruses.