Re: [dmarc-ietf] Benjamin Kaduk's Discuss on draft-ietf-dmarc-psd-12: (with DISCUSS and COMMENT)

Benjamin Kaduk <kaduk@mit.edu> Wed, 12 May 2021 03:26 UTC

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Date: Tue, 11 May 2021 20:25:59 -0700
From: Benjamin Kaduk <kaduk@mit.edu>
To: Tim Wicinski <tjw.ietf@gmail.com>
Cc: The IESG <iesg@ietf.org>, draft-ietf-dmarc-psd@ietf.org, dmarc-chairs@ietf.org, IETF DMARC WG <dmarc@ietf.org>, Alexey Melnikov <alexey.melnikov@isode.com>
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Subject: Re: [dmarc-ietf] Benjamin Kaduk's Discuss on draft-ietf-dmarc-psd-12: (with DISCUSS and COMMENT)
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Thanks, Tim -- no further comments from my side.

-Ben

On Tue, May 11, 2021 at 07:16:26PM -0400, Tim Wicinski wrote:
> On Tue, May 11, 2021 at 12:24 AM Benjamin Kaduk <kaduk@mit.edu> wrote:
> 
> > Hi Tim,
> >
> >
> > > >
> > > > ----------------------------------------------------------------------
> > > > COMMENT:
> > > > ----------------------------------------------------------------------
> > > >
> > > > This document is generally in pretty good shape; my comments (and,
> > > > to some extent, my discuss as well) are pretty minor points.
> > > >
> > > > Thanks to Sandra Murphy for the secdir review.  I think there were some
> > > > questions in there that are worth a response and possibly
> > clarifications
> > > > in the document.
> > > >
> > > >
> > > Sandra did a strong review and I believe we worked through the issues
> > > raised.
> >
> > I'm happy to hear it; I may have just been misled by the mailarchive entry
> > for the secdir list.
> >
> 
> There was a Large GENART review that had us rework several sections
> which were ones that Sandra had also mentioned.  I will go back and
> read her email again just to make sure.
> 
> 
> > >
> > > > Section 1.2
> > > >
> > > > It seems like the "branded PSD" and "multi-organization PSD" cases
> > would
> > > > benefit from a protocol-level indication and separate handling by
> > > > message recipients.  It seems likely that the newly defined np (in
> > > > combination with the preexisting sp) provides the flexibility to
> > > > describe the different cases, but it seems like it would be helpful to
> > > > have some discussion in this document that relates these two cases to
> > > > the actual protocol mechanisms used to achieve them.
> > > >
> > > >
> > > There is no different handling of between a "Branded PSD" and a
> > > "multi-organization PSD".  The difference is highlighting the types.
> >
> > I think I agree that the actual mechanics of handling the protocol
> > elements, if they exist, shouldn't really differ for the two cases.  It
> > seems that there may be some subjective differences, though, in that it
> > would be really surprising if the "multi-organizational PSD" decided to
> > publish policy for existant subdomains, whereas for branded PSDs that is
> > normal and expected, since in some sense they really ought not be PSDs at
> > all.
> >
> 
> Consider the case of the bad actor attempting to publish
> a "multi-organizational PSD" policy for purposes of
> pervasive monitoring.   One of the reasons for the registry
> is to prevent such actions.
> 
> 
> >
> > >
> > > > Section 4.1
> > > >
> > > >    o  Multi-organization PSDs (e.g., ".com") that do not mandate DMARC
> > > >       usage: Privacy risks for Organizational Domains that have not
> > > >       deployed DMARC within such PSDs are significant.  For non-DMARC
> > > >       Organizational Domains, all DMARC feedback will be directed to
> > the
> > > >       PSO.  PSD DMARC is opt-out (by publishing a DMARC record at the
> > > >       Organizational Domain level) vice opt-in, which would be the more
> > > >       desirable characteristic.  This means that any non-DMARC
> > > >       organizational domain would have its feedback reports redirected
> > > >       to the PSO.  The content of such reports, particularly for
> > > >       existing domains, is privacy sensitive.
> > > >
> > > > It might be worth making some statement about the applicability of PSD
> > > > DMARC for such PSDs that do not mandate DMARC usage.  (I guess the
> > > > following paragraphs mostly play that role, though perhaps editorially
> > > > tying them together more clearly is possible.)
> > > >
> > >
> > > I'm not sure where you're going on this, but the following paragraphs do
> > > try to pull it together.  I've been trying to wordsmith these with little
> > > luck.
> > >
> > > Also, it appears that the word "vice" above should be "versus".
> >
> > I suspected it might :)
> >
> > Maybe the following is useful input to your wordsmithing attempts:
> >
> > By definition the new mechanisms in this document result in PSDs receiving
> > feedback on non-existent domains.  However, these non-existent domains may
> > be similar to existing Organizational Domains, and as mentioned above,
> > feedback on existing organizational domains is privacy-sensitive.  To
> > minimize the risk of privacy-sensitive information relating to existing
> > organizational domains being sent to the parent as feedback on a similar
> > non-existent domain, PSD DMARC feedback MUST be limited to Aggregate
> > Reports.  Feedback Reports carry more detailed information and present a
> > greater risk.
> >
> 
> 
> Thanks.  I'm want to also see what the working group thinks/feels
> on the current text and your suggestions.
> 
> 
> > >
> > >
> > > > Or, in the vein of my comment on section 1.2, an explicit protocol
> > > > mechanism could be introduced that limits the reporting to just the
> > > > indicated (public suffix) domain and does not apply to subdomains.
> > > >
> > > >    organizational PSDs MUST be limited to non-existent domains except
> > in
> > > >    cases where the reporter knows that PSO requires use of DMARC.
> > > >
> > > > Do we have examples of how the reporter might come to know this?
> > > > Say ... Appendix B.2?
> > > >
> > > >
> > > Roman raised a similiar point.   I was thinking of adding
> > >     "(by checking the DMARC PSD Registry)"
> > >
> > > or would a full sentence be used to bring the point back home?
> >
> > I don't see a need for a full sentence.  I would check whether an "e.g." is
> > warranted, vs the registry being the only way to do so.
> >
> 
> Okay, I'll add this and will figure out the "e.g."
> 
> 
> > > > Appendix B.1
> > > >
> > > >    A sample stand-alone DNS query service is available at
> > > >    [psddmarc.org].  It was developed based on the contents suggested
> > for
> > > >
> > > > "DNS query service" is so generic so as to be almost meaningless.  Even
> > > > if we defer usage instructions to the external site, we should probably
> > > > say a bit more about what it is expected to do.
> > > >
> > > I tend to agree with you here.  The only other options I could come
> > > up with is "PSD DMARC Lookup service".    I'll try a few others.
> >
> 
> I am leaning toward "DNS Lookup service", which fits into my DNS
> world view.
> 
> tim