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Tue, 11 Dec 2007

Rob Auger from OWASP/WASC/CGiSecurity on Timing..

Rob had a rant on his site on the timing attack, with a CSRF twist.. We met him after our Vegas talk, but im not really sure how his attack differs from our published one..

my on-list response:

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From: haroon meer 
To: bugtraq@cgisecurity.net
Cc: websecurity@webappsec.org
Subject: Re: [WEB SECURITY] Performing Distributed Brute Forcing of CSRF
vulnerable login pages

Hi Robert..

Thanks for the kind words on the talk.. If you check out the visio at: http://www.sensepost.com/blogstatic/2007/08/dxsrt.png you will see that its pretty much the same attack.. In a shameless display of self-pimpage, check out the paper http://www.sensepost.com/research/squeeza/dc-15-meer_and_slaviero-WP.pdf from page 12.. Figure 23 for example shows the results in a victim/zombies browser, after he has visited our page.. Effectively he tries the userlist we send him (in this case on a standard squirrelmail login page). Once he detects a timing diff (again using a trivial algorithm to avoid latency disparity) he simply makes another request to the attacker to report his success..

We do give the important pieces of the script in the paper, but i suspect anyone with 2 minutes of time could have cobbled them together anyway..

/mh

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