May 8, 2015
CS Open Area
Speaker: Laurent Vanbever, Assistant Professor, ETH Zürich
Tor is by far the largest and most widely used anonymity system. As of February 2015, it comprises more than 7,000 relays or proxies which together carry terabytes of anonymous traffic, every day. Despite being so critical for many users, Tor is also known to be vulnerable to attackers who can simultaneously observe traffic entering and leaving the network, supposedly, a hard thing to do.
In this talk, I will present a suite of three new attacks, called Raptor, that can be launched by Autonomous Systems (ASes) to compromise user anonymity. First, I will show how AS-level adversaries can exploit the asymmetric nature of Internet routing to increase its chances of observing at least one direction of user traffic at both ends of the communication. I will then explain how AS-level adversaries can leverage the natural "noise" in Internet routing so as to lie on more paths and for more users over time. Finally, I will show how AS-level adversaries can easily manipulate Internet routing to discover Tor users and intercept their traffic.
Fortunately, Raptor attacks can also be countered. In the last part of my talk, I will describe the two monitoring systems we built to do so. Overall, our work motivates the design of anonymity systems that are aware of the dynamics of Internet routing.
Laurent Vanbever is an Assistant Professor at ETH Zürich where he leads the Networked Systems Group (NSG) since January 2015. Before that, Laurent was a Postdoctoral Research Associate at Princeton University where he collaborated with Jennifer Rexford during two years. He obtained his PhD degree from the University of Louvain in Belgium in 2012. Laurent has won several awards for his research including: the ACM SIGCOMM Doctoral Dissertation Award (runner-up); the University of Louvain Best Thesis Award; the best paper award at the International Conference on Network Protocols (ICNP); and two IETF Applied Networking Research Prizes for his works on inter-domain routing.