-----Original Message-----
From: ietf-dkim-bounces(_at_)mipassoc(_dot_)org
[mailto:ietf-dkim-bounces(_at_)mipassoc(_dot_)org] On Behalf Of Julian Mehnle
Sent: Tuesday, October 05, 2010 7:27 AM
To: ietf-dkim(_at_)mipassoc(_dot_)org
Subject: Re: [ietf-dkim] ISSUE: 4871bis - Security Loop hole with Multiple
5322.From
No. The trick is to list From twice in h=. This ensures more From
headers cannot be added without breaking the signature.
But the attacker in this scenario is already the signer (or has compromised the
signer), so he/she will just sign the single From:.
Perhaps this could be mentioned in the spec with a specific reference
to the From header, but in general terms the spec is pretty clear about
how to prevent the addition of a header field.
From: is already there. The RFC explains how to prevent addition of a field
that wasn't there to begin with, not to prevent addition of new ones.
Enumerating MUA issues, though, is a bottomless pit and not really within our
scope to do. We should avoid it.
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