Subject: [DNSOP] Stephen Farrell's Discuss on draft-ietf-dnsop-5966bis-05: (with DISCUSS)

From: "Stephen Farrell" <[email-masked]>
Date: Wed, 06 Jan 2016 16:09:18 -0800

Stephen Farrell has entered the following ballot position for
draft-ietf-dnsop-5966bis-05: Discuss

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DISCUSS:
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Don't we need text warning that TFO is likely problematic
with DNS privacy and that attacks that try to prepend
information (via TFO) to otherwise secured sessions could
occur? While that might sound a bit far-fetched we have
seen exactly that kind of issue with HTTPS that had
practical impact on Webdav. (The TLS renego and then
triple handshake attacks.) So while using TFO may not
enable a slam-dunk CVE level 10 attack, I think you do
need to consider and talk about it. (Or maybe you did and
figured out no attack can work, but then I'd guess you'd
be so happy, you'd say that too:-)

I'm not sure how this'd best be resolved, but one thing
might be to talk to the folks thinking about TCPINC as
they have at least hit this as a potential issue for
tcpcrypt and for tcp-use-tls.

Otherwise, this is a fine document on which I'll ballot
yes when the above is sorted.

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From: Allison Mankin <[email-masked]>
Date: Thu, 7 Jan 2016 07:40:37 -0500

Hi Stephen,

We're glad you drew this important  point to our attention, but it appears
to be needed for draft-ietf-dprive-dns-over-tls rather than this draft. In
this draft we don't touch on the privacy/TLS motivation for TCP at all,
leaving all that for the dprive draft.

The dprive draft has just completed WGLC. Some of us are authors on both
drafts and we'll propose  text on TFO privacy leakage risks to dprive and
our dprive AD and you.

Thanks,

Allison
On Jan 6, 2016 7:09 PM, "Stephen Farrell" <[email-masked]> wrote:

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From: Stephen Farrell <[email-masked]>
Date: Thu, 7 Jan 2016 14:44:50 +0000

Hi Alison,

> drafts and we'll propose  text on TFO privacy leakage risks to dprive and

That's fine. I guess the only remaining question is whether this
document, which does discuss TFO, should have some sort of generic
warning that mixing plaintext and ciphertext is both possible and
dangerous with a pointer to the dprive draft (as an informative ref)
saying that the details are part of the dprive work. So perhaps
adding a sentence to section 9 that says something like:

"Implementers should be aware that if a DNS privacy mechanism is
being used then there are significant dangers in mixing unprotected
query or response data (from TFO) with protected data. See [dprive]
for the proper way to handle this situation."

And then [dprive] can say if that kind of mixing is a MUST NOT
or whatever, once that's figured out.

Cheers,
S.

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From: "Mankin, Allison" <[email-masked]>
Date: Thu, 7 Jan 2016 15:50:21 +0000

Stephen,

That would work. Thank you for suggesting text; we will go ahead with your suggestion.

Allison

Sent from my iPhone

> On Jan 7, 2016, at 09:45, Stephen Farrell <[email-masked]> wrote:
> 
> 
> Hi Alison,
> 
>> drafts and we'll propose  text on TFO privacy leakage risks to dprive and>> our dprive AD and you.
> 
>>> Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html>>> for more information about IESG DISCUSS and COMMENT positions.
>>> 
>>>