[tor-bugs] #6217 [Tor Browser]: Mozilla updates queries happen at regular intervals

[Tor Bug Tracker & Wiki]

#6217: Mozilla updates queries happen at regular intervals
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 Reporter:  cypherpunks                         |          Owner:  tbb-team
     Type:  defect                              |         Status:  new
 Priority:  Medium                              |      Milestone:
Component:  Tor Browser                         |        Version:
 Severity:  Major                               |     Resolution:
 Keywords:  tbb-linkability, tbb-firefox-patch  |  Actual Points:
Parent ID:                                      |         Points:
  Sponsor:                                      |
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Changes (by cypherpunks):

 * priority:  Low => Medium
 * severity:  Normal => Major


Comment:

 Besides the browser update queries to torproject.org and queries to
 blocklist.addons.mozilla.org, there are addon update queries to
 versioncheck-bg.addons.mozilla.org and www.eff.org (presumably for https
 everywhere).

 Those queries use the same circuit with socks user "--unknown--" and same
 socks password. The versioncheck queries use separate streams with a
 potentially unique transmission size for each. E.g.:

 Stream 1: received: 4135 sent: 1057
 Stream 2: received: 4136 sent: 1055
 Stream 3: received: 4133 sent: 1053
 Stream 4: received: 4125 sent: 1054

 Users that have a few extra addons installed can be uniquely identified.

 TBB should use separate circuits.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/6217#comment:7>
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