Torbutton Documentation - Adversary Capabilities.

[Kyle Williams]

Beware of the Flash and other third-party plugins to your browser.  Flash
can also store "flash cookies" on your system as well.
I would look at "about:plugins" and see what Firefox has loaded.  Torbutton
does a good job at stopping third party plugins, but if you specifically
allow Flash and do not clear the cookie from Flash, you may have a problem.

Other than that, you have the right idea. :)



On Mon, Jul 12, 2010 at 8:45 AM, Matthew <pumpkin at cotse.net> wrote:

>  Hello,
>
> I have been reading the Torbutton documentation (thanks, guys) and have a
> question about the adversary capabilities.
>
> The first adversary capability is "inserting javascript".  The document
> says that "If not properly disabled, Javascript event handlers and timers
> can cause the browser to perform network activity after Tor has been
> disabled, thus allowing the adversary to correlate Tor and Non-Tor activity
> and reveal a user's non-Tor IP address."
>
> The third adversary capability is "inserting CSS".  The document says that
> "CSS can also be used to correlate Tor and Non-Tor activity and reveal a
> user's Non-Tor IP address, via the usage of CSS popups - essentially
> CSS-based event handlers that fetch content via CSS's onmouseover attribute.
> If these popups are allowed to perform network activity in a different Tor
> state than they were loaded in, they can easily correlate Tor and Non-Tor
> activity and reveal a user's IP address."
>
> I understand that Torbutton is useful for protecting privacy in multiple
> ways.  But I would like to address this specific issue if I may.
>
> Let us imagine that a user surfs the net using Tor (and Polipo or
> Privoxy).  He has JavaScript installed and uses it for all sites.  He
> finishes his activities and then closes his browser.  He then wipes the
> following files and directories (I am using Ubuntu as my example):
>
> /.mozilla/firefox/nameofuser/cookies.sqlite
> /.mozilla/firefox/nameofuser/downloads.sqlite
> /.mozilla/firefox/nameofuser/cookies.sqlite-journal
> /.mozilla/firefox/nameofuser/places.sqlite
> /.mozilla/firefox/nameofuser/places.sqlite-journal
> /.mozilla/firefox/nameofuser/formhistory.sqlite
>
> /.mozilla/firefox/nameofuser/Cache/
>
> Now I assume that these Javascript events and handlers and the CSS handlers
> were downloaded into the Cache from when the user was browsing using Tor.
> They would then be deleted as detailed above. Therefore, when the user loads
> up Firefox and turns off the Tor proxy settings, presumably the potential
> for JavaScript or CSS to connect Tor and non-Tor activity and get the users
> real (non-Tor) IP address is no longer a concern?
>
> Is this correct?  Or am I missing something?  Just to re-state: I am only
> looking at this one issue - I am well aware of how useful Tor button is in
> other areas!
>
> Thanks.
>
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