Re: How does Gmail know my local time zone (therefore ignoring the time zone of the Tor exit node) and what else can it see?

2010-09-07 Thread Matthew



On 05/09/10 21:11, Geoff Down wrote:

On Sun, 05 Sep 2010 19:55 +0100, Matthewpump...@cotse.net  wrote:

   Hello,

I have yet another question that relates to the effectiveness of Tor.

Gmail (and therefore presumably other webmail operators) knows my
computer's time zone.  It does not know the time per se but the time
zone
as set (in Ubuntu) through clicking on the clock, selecting preferences,
then choosing location.

Obviously this ignores the time (based on the location) of the Tor exit
node.

I do not know how Gmail knows my computer's time zone, and, in which
case,
what other local information it can know.

Does anyone know how Gmail can do this and what other information from
the
client computer can be viewed.  In other words, why can Gmail not, in
theory, also view the real local IP?

Thanks.

Did you select a time zone when you set up the account?
I assume you are using Torbutton, which blocks Javascript being used to
read your local clock.
GD

AIUI, Gmail uses JavaScript to detect the time zone (but not the time) on 
the client machine.  When I use NoScript with Gmail as untrusted, Gmail 
cannot use JavaScript.  Changing the time zone settings (for example to 
something five hours behind my real time zone) does not then change the 
time at which e-mail appears to arrive in the Gmail inbox since this 
requires JavaScript which is not used since Gmail is considered untrusted.


However, since many websites do require JavaScript, whether or not one is 
using NoScript and / or TorButton, my question was:


If Gmail can get the time zone via JavaScript (when the client is using 
Tor) then why can it not get the real IP also via JavaScript (when the 
client is using Tor)?  I don't think it can get the real IP since I have 
used various tests including http://www.decloak.net/ and Tor with 
JavaScript does not reveal the real IP.  But why not?


Thanks.
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Re: How does Gmail know my local time zone (therefore ignoring the time zone of the Tor exit node) and what else can it see?

2010-09-07 Thread Mike Perry
Thus spake Matthew (pump...@cotse.net):

 On 05/09/10 21:11, Geoff Down wrote:
 Did you select a time zone when you set up the account?
 I assume you are using Torbutton, which blocks Javascript being used to
 read your local clock.
 GD
 
 AIUI, Gmail uses JavaScript to detect the time zone (but not the time) on 
 the client machine.  When I use NoScript with Gmail as untrusted, Gmail 
 cannot use JavaScript.  Changing the time zone settings (for example to 
 something five hours behind my real time zone) does not then change the 
 time at which e-mail appears to arrive in the Gmail inbox since this 
 requires JavaScript which is not used since Gmail is considered untrusted.

Please actually use Torbutton instead of speculating about what
protections it provides, trying to compensate with ad-hoc homebrew
approaches, and then complaining to the list when the results aren't
what you expect.

https://www.torproject.org/torbutton/design/#adversary

Noscript can have all sorts of surprising results when you allow
javascript from other domains.

 However, since many websites do require JavaScript, whether or not one is 
 using NoScript and / or TorButton, my question was:
 
 If Gmail can get the time zone via JavaScript (when the client is using 
 Tor) then why can it not get the real IP also via JavaScript (when the 
 client is using Tor)?  I don't think it can get the real IP since I have 
 used various tests including http://www.decloak.net/ and Tor with 
 JavaScript does not reveal the real IP.  But why not?

Javascript cannot unmask your IP. The attacks on decloak and elsewhere
are all about causing plugins and external applications to launch,
which NoScript does not protect against.

-- 
Mike Perry
Mad Computer Scientist
fscked.org evil labs


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Re: How does Gmail know my local time zone (therefore ignoring the time zone of the Tor exit node) and what else can it see?

2010-09-07 Thread Jan Weiher

 If Gmail can get the time zone via JavaScript (when the client is using
 Tor) then why can it not get the real IP also via JavaScript (when the
 client is using Tor)?  I don't think it can get the real IP since I have
 used various tests including http://www.decloak.net/ and Tor with
 JavaScript does not reveal the real IP.  But why not?

Because there are JavaScript functions to get the current time and
timezone and there are (afaik) no such functions to get some of your
network settings

greetings,
Jan
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