B-Secure: A Dynamic Reputation System for Identifying Anomalous BGP Paths

Abstract

BGP (Border Gateway Protocol) is one of the core internet backbone protocols, which were designed to address the large-scale routing among the ASes (Autonomous System) in order to ensure the reachability among them. However, an attacker can inject update messages into the BGP communication from the peering BGP routers and those routing information will be propagated across the global BGP routers. This could cause disruptions in the normal routing behavior. Specially crafted BGP messages can reroute the traffic path from a source ASN to a specific destination ASN via another path and this attack is termed as AS Path Hijacking. This research work is focused on the detection of suspicious deviation in the AS path between a source and destination ASNs, by analyzing the BGP update messages that are collected by passive peering to the BGP routers. The research mainly focuses on identifying the AS Path Hijacking by quantifying: (1). How far the deviation occurred for a given AS Path and (2). How much credible is the deviated AS path. We propose a novel approach to calculate the deviation occurred by employing weighted edit distance algorithm. A probability score using n-gram frequency is used to determine credibility of the path. Both the scores are correlated together to determine whether a given AS Path is suspicious or not. The experimental results show that our approach is capable of identifying AS path hijacks with low false positives.