[29887] in bugtraq
Re: Cracking preshared keys
daemon@ATHENA.MIT.EDU (Gary Flynn)
Thu Apr 24 18:32:24 2003
Message-ID: <3EA7397A.5010600@jmu.edu>
Date: Wed, 23 Apr 2003 21:10:18 -0400
From: Gary Flynn <flynngn@jmu.edu>
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To: Damir Rajnovic <gaus@cisco.com>
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Damir Rajnovic wrote:
>Please note that the same class of attack is possible even if
>Xauth (Extended Authentication) is used. This is because Xauth is
>performed after Phase 1 is completed and, for this attack, an adversary
>needs only a packet from Phase 1. Furthermore, after the pre-shared
>key has been discovered, an adversary can mount an active MiTM attack
>on Xauth. The outcome depends on the exact authentication method used
>in Xauth.
>
May I ask how this applies to "IKE Shared Secret AAA"?
If a Radius backend authenticator is used, is the shared key
that is vulnerable one preconfigured in the VPN hosts or one
based on the Radius password? The reason I ask is that the
preconfigured shared key can easily be lengthened but the
backend password, if based on end user passwords, is not
as easy a solution. :)
Thank you.
Gary Flynn
Security Engineer - James Madison University
