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Re: [ietf-dkim] DKIM Interoperability Event notes

2007-11-08 17:31:24
Murray S. Kucherawy wrote:
On Thu, 8 Nov 2007, Hector Santos wrote:
Attackers will be able to create a FAILED fascimile of a primary domain DKIM complete message and as long as the primary has a t=y policy, the attackers need not worry about HASH PERFECTION - it just randomly creates a signature with a junk hash because the t=y will promote a IGNORE FAILURE concept.

OK so in fact the complaint is "t=y is dangerous", not "a hacker could insert t=y into someone's policy" (which is what you originally said). There are other people here who can debate that as well as or better than I so I'll yield.

Ok, I didn't say insert, but I can see how it was read.  I stated:

  It is clearly a threat entry point allowing anyone to try to
  create a DKIM signature and all they have to do is add t=y with
  the hope the receiver will ignore all fail validations.

I should of been clear of saying "exploited domains who added t=y into their policy":

  ... and all they have to do is find a DOMAIN with a t=y policy...

In sticking to the Subject: of this thread, no, this was not discussed at the Interop event. SSP was determined early on to be out-of-scope for our tests. We were focusing only on RFC4871 itself.

How unfortunate.

It was felt, though, that SSP might be the subject of a future Interop event once the draft has become an RFC (or, perhaps, multiple proposals are available).

Its unfortunate that SSP continues to be play 2nd fiddle when in fact, in my mind, DKIM is worthless (offers little payoff) without a POLICY concept. I won't recommend DKIM until SSP is part of the fundamental picture.

Anyway, I won't go there.  I just hope the t=y comments are not ignored.

Thanks for your own comments.

--
Sincerely

Hector Santos, CTO
http://www.santronics.com
http://santronics.blogspot.com

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