[tbb-bugs] #28372 [Applications/Tor Browser]: determine if onvisibilitychange is a fingerprinting vector

[Tor Bug Tracker & Wiki]

#28372: determine if onvisibilitychange is a fingerprinting vector
-----------------------------------------+--------------------------
 Reporter:  mcs                          |          Owner:  tbb-team
     Type:  defect                       |         Status:  new
 Priority:  Medium                       |      Milestone:
Component:  Applications/Tor Browser     |        Version:
 Severity:  Normal                       |     Resolution:
 Keywords:  tbb-fingerprinting,ff60-esr  |  Actual Points:
Parent ID:                               |         Points:
 Reviewer:                               |        Sponsor:
-----------------------------------------+--------------------------

Comment (by tom):

 Replying to [comment:3 onvisibilitychange]:
 > > A website could determine:
 > >
 > > - If it was loaded as a prerender client hint (although we probably
 also disable that)
 > > - If the user has backgrounded the tab, minimized the window, their
 screensaver has gone off, screen locked, etc.
 > Where did you find all that states got revealed?

 The specified states are visible, hidden, and prerender. Hidden would tell
 you only that it was hidden, you'd have to guess or guesstimate which of
 the various scenarios I listed had actually occurred. I just listed the
 first things that came to mind that would cause a 'hidden' state.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/28372#comment:4>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online