Thanks Robert.<div>I know that there was several attacks with control of both exit and entry node. </div><div>And I just want to test that attack and evaluate its effectiveness.<br>Regards.<br><div class="gmail_quote">2011/5/11 Robert Ransom <span dir="ltr"><<a href="mailto:rransom.8774@gmail.com">rransom.8774@gmail.com</a>></span><br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">On Wed, 11 May 2011 10:11:07 +0200<br>
NGUYEN Quoc Viet <<a href="mailto:quocviet.pfiev@gmail.com">quocviet.pfiev@gmail.com</a>> wrote:<br>
<br>
> I'm now researching an attack against Tor.<br>
><br>
> *Resume of Attack*: We control exit node and entry node. Upon receiving a<br>
> RELAY BEGIN cell,the exit node will forger a malicious webpage to client.<br>
> The webpage contains some empty gif files. The entry node will be able to<br>
> detect a distinctive pattern of the connection to that malicious webpage,<br>
> basing on number of relay cells backward and forward.<br>
<br>
If you can control both the entry and exit nodes, you don't even need<br>
to perform an active attack -- a purely passive timing attack will<br>
identify the client. That's why each Tor client selects a few relays<br>
to use as ‘entry guards’ -- see<br>
<<a href="https://www.torproject.org/docs/faq#EntryGuards" target="_blank">https://www.torproject.org/docs/faq#EntryGuards</a>> and<br>
<<a href="http://freehaven.net/anonbib/#hs-attack06" target="_blank">http://freehaven.net/anonbib/#hs-attack06</a>>.<br>
<br>
<br>
> For implementation, it's needed to modify a piece of Tor source code at the<br>
> exit node, to forger a malicious webpage to client. Notice that this is not<br>
> modifying webpage response from the server, but forger attacker's webpage to<br>
> the client. Could some one please give a hint about where I need to modify.<br>
<br>
No.<br>
<font color="#888888"><br>
<br>
Robert Ransom<br>
</font><br>_______________________________________________<br>
tor-talk mailing list<br>
<a href="mailto:tor-talk@lists.torproject.org">tor-talk@lists.torproject.org</a><br>
<a href="https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-talk" target="_blank">https://lists.torproject.org/cgi-bin/mailman/listinfo/tor-talk</a><br>
<br></blockquote></div><br><br clear="all"><br>-- <br>Nguyen Quoc Viet<br><br>
</div>