ECE Graduate Seminar Lecture

Science / Technology - Lecture/Discussion - WPI Only

Thursday, November 5, 2009
11:00 AM-12:00 PM

Title:
A New Cell Counter Based Attack Against Tor

Speaker:
Dr. Xinwen Fu
Assistant Professor, Computer Science Department
University of Massachusetts, Lowell

Abstract:
Various low-latency anonymous communication systems such as Tor and Anoymizer have been designed to provide anonymity service for users. In order to hide the communication of users, many anonymity systems pack the application data into equal-sized cells (e.g., 512 bytes for Tor, a known real-world, circuit-based low-latency anonymous communication network).

In this paper, we investigate a new cell counter based attack against Tor, which allows the attacker to confirm anonymous communication relationship among users very quickly. In this attack, by marginally varying the counter of cells in the target traffic at the malicious exit onion router, the attacker can embed a secret signal into the variation of cell counter of the target traffic. The embedded signal will be carried along with the target traffic and arrive at the malicious entry onion router. Then an accomplice of the attacker at the malicious entry onion router will detect the embedded signal based on the received cells and confirm the communication relationship among users. We have implemented this attack against Tor and our experimental data validate its feasibility and effectiveness.

There are several unique features of this attack. First, this attack is highly efficient and can confirm very short communication sessions with only tens of cells. Second, this attack is effective and its detection rate approaches 100% with a very low false positive rate. Third, it is possible to implement the attack in a way that appears to be very difficult for honest participants to detect (e.g. using our hopping-based signal embedding).

Bio:
Dr. Xinwen Fu is an assistant professor in the Department of Computer Science, University of Massachusetts Lowell. He obtained Ph.D. (2005) in Computer Engineering from Texas A&M University. Dr. Fu won the Merrill Hunter Award for Excellence in Research at Dakota State University in 2008 and the best paper award at International Conference on Communications (ICC) 2008.

Dr. Fu's current research interests are in network security and privacy, digital forensics, and networking QoS. Dr. Fu has been publishing papers in conferences such as IEEE Symposium on Security and Privacy (S&P), ACM CCS, IEEE International Conference on Computer Communications (INFOCOM) and IEEE International Conference on Distributed Computing Systems (ICDCS), journals such as IEEE Transactions on Parallel and Distributed Systems (TPDS), and book chapters. His research is supported by NSF.

Host: Professor Wenjing Lou

Suggested Audiences: College

E-mail: ecesec@ece.wpi.edu

Last Modified: October 26, 2009 at 2:05 PM