Web traffic pattern Application-level attack Anonymity

compromise the anonymity of clients without using invasive plugins like Java or any other active content systems in a web browser, posing a serious threat to Tor. Our analytical and empirical results validate the feasibility and effectiveness of the attack. Based on our analysis of the potential attack mechanism, we propose corresponding countermeasures to thwart such potential application-level attacks against Tor, thereby effectively securing and improving Tor networks. Since the fundamental vulnerability exposed by this paper is not specific to web browsing via Tor but rather to the problem of other low-latency applications based on TCP streams, our study is critical for securing and improving low-latency anonymous communication systems. © 2010 Elsevier B.V. All rights reserved. 1