Subject: RE: I-D ACTION:draft-ietf-marid-submitter-02.txt

From: "Terje Petersen" <[email-masked]>
Date: Thu, 22 Jul 2004 13:11:58 +1000

-----Original Message-----
From: [email-masked]
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Sent: Wednesday, 21 July 2004 6:16 AM
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Subject: I-D ACTION:draft-ietf-marid-submitter-02.txt

~~~~~~~

The section of the proposed SUBMITTER standard that I would change is in

part 4.2. 

Currently the last paragraph of that section reads:-

   Verifying MTAs are strongly urged to validate the SUBMITTER parameter
   against the RFC 2822 headers; otherwise, an attacker can trivially
   defeat the algorithm.

I would change this text to say:-

   When a SUBMITTER parameter is provided then receiving MUAs SHOULD
display
   the SUBMITTER parameter as the sender of the email instead of the
   original FROM address in the RFS 2822 headers; otherwise an attacker
can 
   trivially defeat the algorithm by providing a different SUBMITTER and

   FROM address.  

This does not prevent people from developing proprietary email gateways
that 
do this level of header checking also. Rejecting email on the basis of
malformed content or headers is an existing option for administrators
and
nothing in the modification I have suggested takes away this local
policy 
option. I just don't want to see MTAs reading the DATA section as a 
standardised practice.

---

From: Roy Badami <[email-masked]>
Date: Thu, 22 Jul 2004 09:51:19 +0100

>>>>> "Terje" == Terje Petersen <[email-masked]> writes:

    Terje>    When a SUBMITTER parameter is provided then receiving
    Terje> MUAs SHOULD display the SUBMITTER parameter as the sender
    Terje> of the email instead of the original FROM address in the
    Terje> RFS 2822 headers; otherwise an attacker can trivially
    Terje> defeat the algorithm by providing a different SUBMITTER and
    Terje>    FROM address.

But SUBMITTER is a parameter to an SMTP command.  How would the MUA
get to see it?

    -roy

---

From: Dave Crocker <[email-masked]>
Date: Thu, 22 Jul 2004 12:02:43 -0700

Terje,

TP> When a SUBMITTER parameter is provided then receiving MUAs SHOULD
TP> display the SUBMITTER parameter as the sender of the email instead
TP> of the original FROM address in the RFS 2822 headers; otherwise an
TP> attacker can trivially defeat the algorithm by providing a different
TP> SUBMITTER and FROM address.

SUBMITTER is related to rfc2822.Sender, not rfc2822.From.

The concern for display to the user is certainly valid.  However
bypassing the From field creates more problems than it solves.

d/
--
 Dave Crocker <mailto:[email-masked]>
 Brandenburg InternetWorking <http://www.brandenburg.com>
 Sunnyvale, CA  USA <tel:+1.408.246.8253>, <fax:+1.866.358.5301>