Yixin Sun will present her FPO "Enhancing Anonymity Systems under Network and User Dynamics" on Tuesday, December 17, 2019 at 9:30am in CS 402.
The members of her committee are as follows: Advisers: Mung Chiang and Prateek Mittal; Readers: Jennifer Rexford, Prateek Mittal, and Nick Feamster; Nonreaders: Jennifer Rexford, Ed Felten, and Mung Chiang.
Privacy on the Internet is eroding rapidly. Anonymity systems have been
designed to protect the identity and privacy of users from untrusted
destinations and third parties on the Internet. However, many prior
works on anonymity systems assume that important system components,
such as network routing and user location, are static. In practice, these
components are highly dynamic, leading to new vulnerabilities that can
compromise user anonymity. In this dissertation, we exploit dynamics in
anonymity systems across two different layers: network dynamics (i.e.,
changes in routing) at the network layer and user dynamics (i.e., changes
in user location) at the application layer.
First, we present RAPTOR attacks that exploit the dynamics in Internet
routing to compromise user anonymity in the Tor network. The attacks
enable adversaries to observe more user traffic and deanonymize them
more effectively than previously thought. We successfully demonstrate
the attacks by performing them on the live Tor network, ethically.
Second, we build proactive and reactive defenses to protect Tor users
from RAPTOR attacks: (1) a novel Tor relay selection algorithm that
proactively reduces the probability of Tor users being affected by an
attack, and (2) a monitoring system with novel detection analytics that
detect routing anomaly for Tor relays in real time.
Finally, we present attacks that exploit user mobility to compromise user
anonymity across a wide range of anonymity systems. While prior works
assume that user locations are fixed when accessing anonymity systems,
we demonstrate that users can be highly mobile and subsequently expose
themselves to adversaries as they visit more locations.
In summary, we demonstrate the dangers of abstracting dynamics in
Internet routing and user location from the analysis of anonymity
systems, and take the step to design anonymity systems with these
important system components in mind.