ietf-dkim
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Re: [ietf-dkim] Possible exploit of DKIM

2008-11-02 10:58:00
Thiyaga:
Hi,

We recently decided to implement DKIM in our organization.

While reading through the RFC, I found a possible case, where the
authentication is lost.   (Sorry if it is already discussed and a known
issue)

Scenario:
Let's assume a spammer wants to spam email accounts on domain "X.com" and
the spammer uses a domain "Y.com". Both the domains have implemented DKIM.

This looks like a standard replay attack.  Such technique can't be
used to send SPAM on behalf of domains that don't sign SPAM (e.g.,
porcupine.org).  If a domain is willing to sign SPAM, then they
deserve that all their messages are handled with great prejudice.

It is possible to take DKIM-signed messages with signature and all,
and to append SPAM at the bottom, but that is not a very effective
way to reach many eyeballs.

        Wietse
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