-----Original Message-----
From: Frank Ellermann [mailto:nobody(_at_)xyzzy(_dot_)claranet(_dot_)de]
Sent: Thursday, September 07, 2006 7:49 PM
To: ietf(_at_)ietf(_dot_)org
Subject: Re: RFC 2195 (Was: what happened to newtrk?)
Christian Huitema wrote:
both Steve Bellovin and I presented the issues with such
techniques.
Is that presentation online available somewhere ? I find the
way to http://www3.ietf.org/proceedings/05aug/index.html but
then I'm lost.
http://www.huitema.net/talks/ietf63-security.ppt
For a password in the dictionary, and if somebody sees the
challenge and the response. With a somewhat unusual password
I wouldn't know how an attack works.
You would not, but the gentle folks writing the cracking tool certainly
know. From the slide deck:
- If (the password) is generated by the user, it can certainly be
cracked
- If (the password) can be remembered by the user, it can probably be
cracked
Basically, host should only accept password challenges on secure
channels & after properly identifying the server posing the challenge.
CRAM-5 fails both tests. The channel is not encrypted, and the server
can be easily spoof, e.g. in a rogue Wi-Fi hot spot.
Note that this is not related to potential weaknesses in MD5. The
dictionary attack works just fine with other hash functions.
-- Christian Huitema
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