Wietse Venema wrote:
Hector Santos:
Wietse Venema wrote:
If the verifier gives different treatments to different types of
"other", then the bad guys will exploit the verifier's behavior.
Applying equal treatment should be done across the board, the valid and
invalid, not just for the so called "elite" messages.
It is with the exceptions and relaxed provisions where exploitation will
take place, the FSUSP (FAILED SIGNATURE UNSIGNED STATUS PROMOTION) is
one of them.
Perhaps I wasn't clear enough.
When a DKIM verifier gives unequal treatment to any of the following:
- no signature
- broken signature
- unsupported signature
- other failure
Then the bad guys will send their forged mail in the way that receives
the most favorable treatment.
You kidding me?
Of course its clear, I wrote a IEFT DRAFT on the subject:
http://www.isdg.net/public/ietf/drafts/draft-santos-dkim-dsap-00.html
I've been the #1 vocal point on FAILURE HANDLING. What you guys wish to
do is ignore failure and only look for the "good needle in the haystack"
(small percentage of valid DKIM messages) and that my friend is the
mirror image of the same exploitation you are know concern about.
What is surprising is that you finally coming around to the idea that
having an non-official way of failure handling is a PROBLEM. Oye Vey!
--
HLS
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