The Border Gateway Protocol (BGP) is a fundamental component of the current Internet infrastructure. Due to the inherent trust relationship between peers, control of a BGP router could enable an attacker to redirect traffic allowing man-in-the-middle attacks or to launch a large-scale denial of service. It is known that BGP has weaknesses that are fundamental to the protocol design. Many solutions to these weaknesses have been proposed, but most require resource intensive cryptographic operations and modifications to the existing protocol and router software. For this reason, none of them have been widely adopted. However, the threat necessitates an effective, immediate solution.
We propose a system that is capable of detecting malicious inter-domain routing update messages through passive monitoring of BGP traffic. This approach requires no protocol modifications and utilizes existing monitoring infrastructure. The technique relies on a model of the autonomous system connectivity to verify that route advertisements are consistent with the network topology. By identifying anomalous update messages, we prevent routers from accepting invalid routes. Utilizing data provided by the Route Views project, we demonstrate the ability of our system to distinguish between legitimate and potentially malicious traffic.