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authorRasmus Dahlberg <rasmus@rgdd.se>2024-10-15 16:08:16 +0200
committerRasmus Dahlberg <rasmus@rgdd.se>2024-10-15 16:08:16 +0200
commit385cc92bc91e1a6c3724085c060e76bf40c13ed3 (patch)
tree26d0a8f81f2caa472830fd40a51844bb202c1355 /summary/src/tlwo/main.tex
Import PhD thesis
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+\begin{kaupaper}[
+ author={%
+ \textbf{Rasmus Dahlberg} and
+ Tobias Pulls
+ },
+ title={%
+ Timeless Timing Attacks and Preload Defenses in Tor's DNS Cache
+ },
+ reference={%
+ USENIX Security (2023)
+ },
+ summary={%
+ Tor relays cache resolved domains with constant time-to-live values not to
+ reveal information about past exit traffic while boosting performance. We
+ show that this caching strategy and its implementation in the live Tor
+ network can be exploited by a \emph{timeless timing attack} that leaks if a
+ domain is (not) cached. Further, the time that a domain was inserted into
+ the cache can be inferred by repeated probes. Our attack prototype's
+ experimental evaluation in real conditions shows that there are neither
+ false positives nor false negatives (10M~repetitions). Thus, it is useful
+ for instantiating a real-world website oracle without requiring any special attacker
+ capabilities or reach (just a modest computer that can create a Tor
+ circuit). One of our mitigations has been merged in Tor: probabilistic
+ time-to-live values that make the time-of-insertion fuzzy. Long-term,
+ Tor's DNS cache could be redesigned to \emph{preload} the same domains at all
+ exits. Such preloading would eliminate all (timeless) timing attacks in
+ Tor's DNS cache because the same domains would always be (un)cached across
+ different circuits. To retain performance within the same circuit, we
+ propose that the preloaded domains should be complemented by a dynamic
+ same-circuit cache that is not shared across circuits. Our
+ four-month-long DNS cache measurement at two 100~Mbit/s exit relays
+ informs on today's baseline performance. It is compared to a preloaded
+ DNS cache based on different variations of three popularity lists: Alexa,
+ Tranco, and Umbrella. A preloaded DNS cache can be as performant as today
+ with similar resource usage or significantly improve cache-hit ratios by
+ 2-3x. However, the increased cache-hit ratios have the cost of modest
+ increases in memory and resolver load.
+ },
+ participation={\vspace{-.25cm}
+ Tobias and I collaborated closely from start to finish with the following
+ exceptions. I did most implementation work. Volunteers from DFRI---a
+ Swedish non-profit and non-partisan organization that promotes digital
+ rights---operated our exit relays. Tobias did most DNS cache data
+ analysis. Tobias also had the initial idea, which was refined with
+ feedback~from~Roger~Dingledine.
+ },
+ label={
+ paper:tlwo
+ },
+]
+ \maketitle
+ \begin{abstract}
+ \input{src/tlwo/src/abstract}
+ \end{abstract}
+
+ \input{src/tlwo/src/introduction}
+ \input{src/tlwo/src/background}
+ \input{src/tlwo/src/tor-cache}
+ \input{src/tlwo/src/attack}
+ \input{src/tlwo/src/short}
+ \input{src/tlwo/src/long}
+ \input{src/tlwo/src/related}
+ \input{src/tlwo/src/conclusion}
+ \input{src/tlwo/src/acknowledgements}
+ \input{src/tlwo/src/availability}
+
+ \bibliographystyle{plain}
+ \bibliography{src/tlwo/src/ref}
+\end{kaupaper}