Subject: Re: e2e security (was Re: stats from the text conferencing experiment)

From: Margaret Wasserman <[email-masked]>
Date: Tue, 26 Nov 2002 14:50:12 -0500

Hi Steve,

>All it would take would be one IETFer who has turned to the dark side
>and signed a spammer's key.

What makes you think that there aren't spammers amongst us today?
Much of the spam I receive is from otherwise seemingly reputable
companies...

Margaret

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From: "Steven M. Bellovin" <[email-masked]>
Date: Tue, 26 Nov 2002 14:37:10 -0500

In message <[email-masked]>, Derek Atkins writes:
>"Steven M. Bellovin" <[email-masked]> writes:
>
>> Probably works, though I'd worry about a Web of Spam...
>
>When spammers start submitting PGP keys and signing spam messages
>will be the day we've won.
>

All it would take would be one IETFer who has turned to the dark side 
and signed a spammer's key.  That spammer would then create a web of 
keys, some inconspicuous element of which would sign the spam.  Sure, 
we could zap that key, but it's disposable, anyway.  The next spam 
wouldn't come from anywhere near that place on the Web of Spam.

		--Steve Bellovin, http://www.research.att.com/~smb (me)
		http://www.wilyhacker.com ("Firewalls" book)

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From: Dean Willis <[email-masked]>
Date: 26 Nov 2002 13:50:08 -0600

> wouldn't come from anywhere near that place on the Web of Spam.

That's why I proposed a simple single-root with logging. The
transitivity would be be easy to hunt down and revoke. Yes, it's
centralized and totalitarian. That's the definition of "manageable",
and what we have is really a management problem. Sorry, Randy.
Maybe if we learn how to manage it in the small, we'll catch enough
clues to support liberty too . . .

-- 
Dean Willis <[email-masked]>

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From: "Theodore Ts'o" <[email-masked]>
Date: Tue, 26 Nov 2002 15:58:22 -0500

> wouldn't come from anywhere near that place on the Web of Spam.

Identifying the IETF'er who had turned to the Dark Side (call him
Darth Maul) would be fairly trivial.  The spammer's Web of Spam will
only be connected to the the IETF Web of Trust by only one or a few
points.  So it doesn't take much analysis before those interconnection
points would become glaringly obvious, and then we can ask that person
to either (a) revoke his signature on the spammer's key, or (b) the
identity of Darth Maul himself could be placed on individuals' black
lists as not being trusted to certify other keys.

						- Ted

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From: David Meyer <[email-masked]>
Date: Tue, 26 Nov 2002 11:58:50 -0800

>> wouldn't come from anywhere near that place on the Web of Spam.

Exactly.

Dave

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From: Derek Atkins <[email-masked]>
Date: 26 Nov 2002 14:51:04 -0500

> and signed a spammer's key.  That spammer would then create a web of

Then make it 3 "known keys", or some other number of required
signatures to auto-subscribe...

> wouldn't come from anywhere near that place on the Web of Spam.

Well, one could always start tracing back the keys in the Web..  At
some level the moderator has direct knowledge of SOME people, and you
can work backwards.  Also, one could notice a lot of subscriptions
coming in at once.

My point is that, as an experiment, I think this would be an easy one
to run, and it would probably block MOST spam.  I don't think spammers
would care sufficiently to hack around this, and if they do, well, we
can raise the bar some more.

Just because the solution is not perfect 100% of the time does not mean
that it is not _sufficient_.

-derek

-- 
       Derek Atkins
       Computer and Internet Security Consultant
       [email-masked]             www.ihtfp.com

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From: Paul Hoffman / IMC <[email-masked]>
Date: Wed, 27 Nov 2002 11:07:52 -0800

At 2:51 PM -0500 11/26/02, Derek Atkins wrote:
>to run, and it would probably block MOST spam.

Your view of "easy" may not be shared by the rest of us, particularly 
those who have to administer mailing lists outside the Security area. 
(Heck, I highly doubt it would work easily on many mailing lists 
inside the Security area.)

>that it is not _sufficient_.

Just because there is a solution doesn't mean that it fits the problem.

--Paul Hoffman, Director
--Internet Mail Consortium