SSL would prevent it, Re: Internet security flaw exposes private data

[David Farber <dave () farber net>]

Begin forwarded message:

From: "Ed Gerck, Ph.D." <egerck () nma com>
Date: January 17, 2010 12:05:18 PM EST
To: dave () farber net
Cc: ip <ip () v2 listbox com>
Subject: SSL would prevent it, Re: [IP] Internet security flaw exposes private data

[Dave: For IP, with your consideration]

The sky is not falling.

With at least one authenticated end-point (the end-point server, as usual), SSL would NOT allow a AT&T caching server 
that sits in-between to have had a "correct" SSL session between the wrong two end-points. See A. Menezes et al., 
/Handook of Applied Cryptography/, CRC Press, New York, 1997.

This statement is true even if the AT&T caching server is able not only to modify packets but also to drop incoming 
packets and insert its own packets at will into the traffic, and do so in two-way communication without delay, becoming 
an active man-in-the-middle (which a passive, caching server is not).

This should not be confused with a phishing attack, where the end-user is tricked to go to (for example) 
paypal.fraud.com instead of paypal.com -- and the server end-point is already wrong, or a "bridge" attack where 
(without noticing it) the user goes to the wrong server before SSL starts -- and stays there after SSL starts. The 
second user did reach facebook.com and this would have been enough under one-point authenticated SSL to prevent the 
first user session to be hijacked (which is what happened) as it would not have the correct session keys.

Best regards,
Ed Gerck
www.gerck.com

> *From:* Dave CROCKER <dhc2 () dcrocker net <mailto:dhc2 () dcrocker net>>
>
> It's probably important to bust this popular myth:  regular SSL use would have done nothing for preventing or 
> resolving this problem.
>
> Typical use of SSL provides privacy from wiretapping, but does not prevent misdirection of the connection during 
> setup.
>
> If AT&T was misdirection initial connection setup, then that connection setup would merely have had a "correct" SSL 
> session between the wrong two end-points.





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