[tbb-bugs] #13858 [Tor Browser]: Resolution fingerprinting possible with Tor Browser Bundle

Tor Bug Tracker & Wiki blackhole at torproject.org
Fri Nov 28 23:19:59 UTC 2014

#13858: Resolution fingerprinting possible with Tor Browser Bundle
 Reporter:  sleurn       |          Owner:  tbb-team
     Type:  defect       |         Status:  new
 Priority:  major        |      Milestone:
Component:  Tor Browser  |        Version:
 Keywords:               |  Actual Points:
Parent ID:               |         Points:
 There seems to be a major problem in terms of screen size (resolution)
 fingerprinting possibility - checked on https://panopticlick.eff.org:

 E.g., plain Firefox 33.1.1 on WinXP SP3 Home 32 bit is shown as
 1024x600x24, independently of whether the menu bar is shown or not.

 On the other hand, torbrowser-install-4.0.1_en-US.exe on the same machine
 causes following instead:
 - With menu bar shown (default): 1024x476x24 ("one in 1183729.75 browsers
 have this value")
 - With menu bar disabled: 1024x499x24 ("one in 175367.48 browsers have
 this value")

 As far as I remember, pre-4.0 versions of TBB had some hard-coded commonly
 used value, such as 1024x768x24 or something.

Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13858>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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