\begin{kaupaper}[
    author={%
      Tobias Pulls and \textbf{Rasmus Dahlberg}
    },
    title={%
      Website Fingerprinting with Website Oracles
    },
    reference={%
      PETS (2020)
    },
    summary={%
      One of the properties Tor aims to provide against local network attackers
      is unlinkability between end-users (sender anonymity set) and their
      destinations on the Internet (receiver anonymity set).  A website
      fingerprinting attack aims to break anonymity in this model by inferring
      which website an identifiable end-user is visiting based only on the
      traffic entering the Tor network.  We extend the attacker model for
      website fingerprinting attacks by introducing the notion of \emph{website
      oracles}.  A website oracle answers the following question: was website $w$
      visited during time frame $t$?  In other words, the attacker can query the
      receiver anonymity set for websites that were (not) visited.  Our
      simulations show that augmenting past website fingerprinting attacks to
      include website oracles significantly reduces false positives for all but
      the most popular websites, e.g., to the order of $10^{-6}$ for
      classifications around Alexa top-10k and much less for the long tail of
      sites.  Further, some earlier website fingerprinting defenses are largely
      ineffective in the (stronger) attacker model that includes website
      oracles.  We discuss a dozen real-world website oracles ranging from
      centralized access logs to widely accessible real-time bidding platforms
      and DNS caches, arguing that they are inherent parts of the protocols used
      to perform website visits.  Therefore, access to a website oracle should
      be an assumed attacker capability when evaluating which website
      fingerprinting defenses are effective.
    },
    participation={\vspace{-.25cm}
      Tobias is the main author and conducted most of the work.  I mainly
      contributed by coining the name \emph{website oracle}, evaluating
      sources of real-world website oracles, and performing our non-simulated
      network experiments.
    },
    label={
      paper:cat
    },
]
  \maketitle
  \begin{abstract}
    \input{src/cat/src/abstract}
  \end{abstract}

  \input{src/cat/src/intro}
  \input{src/cat/src/background}
  \input{src/cat/src/oracles}
  \input{src/cat/src/sources}
  \input{src/cat/src/sim}
  \input{src/cat/src/wf}
  \input{src/cat/src/discussion}
  \input{src/cat/src/related}
  \input{src/cat/src/conclusions}
  \input{src/cat/src/ack}

  \bibliographystyle{plain}
  \bibliography{src/cat/src/ref-min}
  
  \begin{appendices}
    \input{src/cat/src/bayes}
    \input{src/cat/src/lessons}
    \input{src/cat/src/othersources}
  \end{appendices}

\end{kaupaper}
