Boten ELISA: A novel approach for botnet C&C in Online Social Networks

The Command and Control (C&C) channel of modern botnets is migrating from traditional centralized solutions (such as the ones based on Internet Relay Chat and Hyper Text Transfer Protocol), towards new decentralized approaches. As an example, in order to conceal their traffic and avoid blacklisting mechanisms, recent C&C channels use peer-to-peer networks or abuse popular Online Social Networks (OSNs). A key reason for this paradigm shift is that current detection systems become quite effective in detecting centralized C&C. In this paper we propose ELISA (Elusive Social Army), a botnet that conceals C&C information using OSNs accounts of unaware users. In particular, ELISA exploits in a opportunistic way the messages that users exchange through the OSN. Furthermore, we provide our prototype implementation of ELISA. We show that several popular social networks can be maliciously exploited to run this type of botnet, and we discuss why current traffic analysis systems cannot detect ELISA. Finally, we run a thorough set of experiments that confirm the feasibility of our proposal. We have no evidence of any real-world botnets that use our technique to create C&C channels. However, we believe that finding out in advance potential new types of botnets will help to prevent possible future malevolent applications.