Scalable Stealth Mode P2P Overlays of Very Small Constant Degree

Abstract

P2P technology has recently been adopted by Internet-based malware as a fault tolerant and scalable communication medium. Due to its decentralized and self-organizing nature, P2P malware is harder to detect and block, especially if it utilizes specialized techniques for hiding. We analyze a number of hiding strategies through extensive and realistic simulations over a model of the AS-level Internet topology. We show that the most effective strategy to avoid detection is to drastically reduce the maximal number of peers a node communicates with. While overlay networks of a small constant maximal degree are generally considered to be unscalable, we argue that it is possible to design them to be scalable, efficient, and robust. An important implication is that stealth mode P2P malware that is very difficult to discover with state-of-the-art methods is a plausible threat. We discuss algorithms and theoretical results that support the scalability of stealth mode overlays, and we present realistic event-based simulations of a proof-of-concept system. Besides the context of P2P malware, some of our results are of general interest in the area of constant degree overlays in connection with the problem of how to maintain reasonable performance and reliability with the smallest degree possible.