Anonymity on QuickSand: Using BGP to Compromise Tor

Authors: Laurent Vanbever, Oscar Li, Jennifer Rexford, and Prateek Mittal
Proceedings of the 13th ACM Workshop on Hot Topics in Networks 2014


Anonymity systems like Tor are known to be vulnerable to malicious relay nodes. Another serious threat comes from the Autonomous Systems (ASes) that carry Tor traffic due to their powerful eavesdropping capabilities. Indeed, an AS (or set of colluding ASes) that lies between the client and the first relay, and between the last relay and the destination, can perform timing analysis to compromise user anonymity. In this paper, we show that AS-level adversaries are much more powerful than previously thought. First, routine BGP routing changes can significantly increase the number of ASes that can analyze a user’s traffic successfully. Second, ASes can actively manipulate BGP announcements to put themselves on the paths to and from relay nodes. Third, an AS can perform timing analysis even when it sees only one direction of the traffic at both communication ends. Actually, asymmetric routing increases the fraction of ASes able to analyze a user’s traffic. We present a preliminary evaluation of our attacks using measurements of BGP and Tor. Our findings motivate the design of approaches for anonymous communication that are resilient to AS-level adversaries.



	title={Anonymity on quicksand: Using bgp to compromise tor},
	author={Vanbever, Laurent and Li, Oscar and Rexford, Jennifer and Mittal, Prateek},
	booktitle={Proceedings of the 13th ACM Workshop on Hot Topics in Networks},

DOI: 10.1145/2670518.2673869