RE: CISCO MD5 encryption

["David Gillett" <gillettdavid () fhda edu>]

  Good point.  There may indeed be ways to construct {s1, s2} that don't
help you construct s2 given h(s1).  A way to construct s2 given h(s1) WOULD
BE a collision attack, but *for all I know* the actual collision attacks
that have been found might not be able to be used this way.

David Gillett


-----Original Message-----
From: Paul Johnston [mailto:paul.johnston () pentest co uk]
Sent: Friday, February 25, 2011 06:34
To: security-basics () securityfocus com
Subject: Re: CISCO MD5 encryption

Hi,

> Since you can copy the running configuration text file to a virgin
> device and it all works, I'd say that there's an excellent chance that
> any password entered will be accepted if the hash matches -- that is,
> an engineered collision is as good as recovery of the actual password.

I expect you're right, at least that if you found another password that
hashed to the same as the stored hash you'd get in.

But that is not what the collision attacks are about. They let you find two
strings, s1 and s2 where s1!=s2 but h(s1)==h(s2). They do not help you find
s1 when you already know h(s1). To use an engineered collision, you'd have
to be able to control the stored hash, or the administrator's password.
Clearly if you can do that, you have easier routes to take control of the
system that any cryptographic attack.

Paul

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------------------------------------------------------------------------
Securing Apache Web Server with thawte Digital Certificate
In this guide we examine the importance of Apache-SSL and who needs an SSL certificate.  We look at how SSL works, how 
it benefits your company and how your customers can tell if a site is secure. You will find out how to test, purchase, 
install and use a thawte Digital Certificate on your Apache web server. Throughout, best practices for set-up are 
highlighted to help you ensure efficient ongoing management of your encryption keys and digital certificates.

http://www.dinclinx.com/Redirect.aspx?36;4175;25;1371;0;5;946;e13b6be442f727d1
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