Towards collaborative security and P2P intrusion detection

The increasing array of Internet-scale threats is a pressing problem for every organization that utilizes the network. Organizations have limited resources to detect and respond to these threats. The end-to-end (E2E) sharing of information related to probes and attacks is a facet of an emerging trend toward "collaborative security." The key benefit of a collaborative approach to intrusion detection is a better view of global network attack activity. Augmenting the information obtained at a single site with information gathered from across the network can provide a more precise model of an attacker's behavior and intent. While many organizations see value in adopting such a collaborative approach, some challenges must be addressed before intrusion detection can be performed on an inter-organizational scale. We report on our experience developing and deploying a decentralized system for efficiently distributing alerts to collaborating peers. Our system, Worminator, extracts relevant information from alert streams and encodes it in Bloom Filters. This information forms the basis of a distributed watchlist. The watchlist can be distributed via a choice of mechanisms ranging from a centralized trusted third party to a decentralized P2P-style overlay network.