On the feasibility of exploiting P2P systems to launch DDoS attacks

We show that malicious nodes in a peer-to-peer (P2P) system may impact the external Internet environment, by causing large-scale distributed denial of service (DDoS) attacks on nodes not even part of the overlay system. This is in contrast to attacks that disrupt the normal functioning, and performance of the overlay system itself. We demonstrate the significance of the attacks in the context of mature and extensively deployed P2P systems with representative and contrasting membership management algorithms—Kad, a DHT-based file-sharing system, and ESM, a gossip-based video broadcasting system. We then present an evaluation study of three possible mitigation schemes and discuss their strength and weakness. These schemes include (i) preferring pull-based membership propagation over push-based; (ii) corroborating membership information through multiple sources; and (iii) bounding multiple references to the same network entity. We evaluate the schemes through both experiments on PlanetLab with real and synthetic traces, and measurement of the real deployments. Our results show the potential of the schemes in enhancing the DDoS resilience of P2P systems, and also reveal the weakness in the schemes and regimes where they may not be sufficient.