Biblio
Botnets have become one of the most significant cyber threats over the last decade. The diffusion of the "Internet of Things" and its for-profit exploitation, contributed to botnets spread and sophistication, thus providing real, efficient and profitable criminal cyber-services. Recent research on botnet detection focuses on traffic pattern-based detection, and on analyzing the network traffic generated by the infected hosts, in order to find behavioral patterns independent from the specific payloads, architectures and protocols. In this paper we address the periodic behavioral patterns of infected hosts communicating with their Command-and-Control servers. The main novelty introduced is related to the traffic analysis in the frequency domain without using the well-known Fast Fourier Transform. Moreover, the mentioned analysis is performed through the exploitation of the proxy logs, easily deployable on almost every real-world scenario, from enterprise networks to mobile devices.
Botnets are considered one of the most dangerous species of network-based attack today because they involve the use of very large coordinated groups of hosts simultaneously. The behavioral analysis of computer networks is at the basis of the modern botnet detection methods, in order to intercept traffic generated by malwares for which signatures do not exist yet. Defining a pattern of features to be placed at the basis of behavioral analysis, puts the emphasis on the quantity and quality of information to be caught and used to mark data streams as normal or abnormal. The problem is even more evident if we consider extensive computer networks or clouds. With the present paper we intend to show how heuristics applied to large-scale proxy logs, considering a typical phase of the life cycle of botnets such as the search for C&C Servers through AGDs (Algorithmically Generated Domains), may provide effective and extremely rapid results. The present work will introduce some novel paradigms. The first is that some of the elements of the supply chain of botnets could be completed without any interaction with the Internet, mostly in presence of wide computer networks and/or clouds. The second is that behind a large number of workstations there are usually "human beings" and it is unlikely that their behaviors will cause marked changes in the interaction with the Internet in a fairly narrow time frame. Finally, AGDs can highlight, at the moment, common lexical features, detectable quickly and without using any black/white list.