IETF Logo Mail Archive

Re: [Doh] Suggestion on draft-ietf-doh-dns-over-https-13: Recommend DANE-TLS to authenticate the TLS-certificate

Eric Rescorla <ekr@rtfm.com> Thu, 16 August 2018 16:16 UTC

Return-Path: <ekr@rtfm.com>
X-Original-To: doh@ietfa.amsl.com
Delivered-To: doh@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 486AE130DE2 for <doh@ietfa.amsl.com>; Thu, 16 Aug 2018 09:16:41 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.909
X-Spam-Level:
X-Spam-Status: No, score=-1.909 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, T_DKIMWL_WL_MED=-0.01] autolearn=unavailable autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (2048-bit key) header.d=rtfm-com.20150623.gappssmtp.com
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id oHOWGXeRiIPc for <doh@ietfa.amsl.com>; Thu, 16 Aug 2018 09:16:37 -0700 (PDT)
Received: from mail-lf1-x136.google.com (mail-lf1-x136.google.com [IPv6:2a00:1450:4864:20::136]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 34FA51252B7 for <doh@ietf.org>; Thu, 16 Aug 2018 09:16:37 -0700 (PDT)
Received: by mail-lf1-x136.google.com with SMTP id f135-v6so3802104lfg.10 for <doh@ietf.org>; Thu, 16 Aug 2018 09:16:37 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rtfm-com.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=5aAruh7kpAF0L5XYomh+HqdPJRv9jsxKBMo7ntvG5oI=; b=byB2PCMUHZyCxs+jaNpoIv7I/kYTaGHEALFQRK5c0dx6xvaNp7ecy+obak5uHG8ZkG or5x5UBJohAPL1Le5md7VlEqE0o6qp3qHiYu13BEn8J7W7XGBCdfwK610wOB7Gpv3Bvh /s4X4M5p3Nhmb+x0KoGIUdp4mF1kizqptKtDMvMPLY+PzEag5fdpNjr0+NiFD5uU4y4N K2nlnS3FIA9GTy3lSioK/4+vbuRUH3bc6bVtsvlMpBNaA/+D5fX+B2CpJQoiRbw73iSZ K0Knj110U6Hf8uZ4rreA3PyDG+h0AlsIeHZRW9hHCVAfyJY0ntBNOZMEzbJ2E6HS7DEy n/nA==
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=5aAruh7kpAF0L5XYomh+HqdPJRv9jsxKBMo7ntvG5oI=; b=MXB47wS8CHsXqnd6pusph7BSeAZmPOTRKWa7hH/PJ5ToS/4NnYdaH17BpQUiSoDbLT jXrUlIMzRBbx5aIrFmvaZ7r0n0BrDUhqCaYjmVQsdXzNo0N+ncVzTVtWpa9wOorG0uja 4h86z4jC2w8DzYImsXHHvjvCzVt2uKOpM7eNUM/4LzjD1ZofN8ew/akF6GNElMNeAmT6 9HSmncUS0fXfuyJzr4mWY78M0YYs+s7qNE6XiJgY2ZDDRWhCLc0BQCISjIGfEjPIHDpS sVEqc6C0Wkwb7Zct9Te+DuNKLS5iCouoRV11itQaqrYCib4coJ368QxiJyzAcb1guElm JoRg==
X-Gm-Message-State: AOUpUlErwypikPGECpQO2H1hR7IP32AW3CV4i68cATPOPRBdK0NXhmNh /r9XgZk4fGIDCUgEMnyZ5C2IE0r4+TZezlndmrmWJ3xu
X-Google-Smtp-Source: AA+uWPxCBB3zz+qjTZ3FcBBNik9hmruxdGwGni0n3FpsboqlLViyO7WufR+dGHh9CWYgos2kbQX65JQ3m284m7HutT8=
X-Received: by 2002:a19:cb93:: with SMTP id b141-v6mr1904803lfg.119.1534436195085; Thu, 16 Aug 2018 09:16:35 -0700 (PDT)
MIME-Version: 1.0
Received: by 2002:ab3:4091:0:0:0:0:0 with HTTP; Thu, 16 Aug 2018 09:15:54 -0700 (PDT)
In-Reply-To: <57f33ab2-4af1-8760-5d0b-7f85612aea56@bartschnet.de>
References: <6fb4a552-8d5e-494b-f934-1f97b83b0ab6@bartschnet.de> <CABcZeBMGedNJx_bEResOQKHp4eRFuvrZg_QpQ3DSK_zo-yjU0A@mail.gmail.com> <57f33ab2-4af1-8760-5d0b-7f85612aea56@bartschnet.de>
From: Eric Rescorla <ekr@rtfm.com>
Date: Thu, 16 Aug 2018 09:15:54 -0700
Message-ID: <CABcZeBMb+kSUPP1udMkttH=mDWJV3X3VEJ3VwavNH5ZaBJZUKw@mail.gmail.com>
To: "Rene 'Renne' Bartsch, B.Sc. Informatics" <ietf=40bartschnet.de@dmarc.ietf.org>
Cc: DoH WG <doh@ietf.org>
Content-Type: multipart/alternative; boundary="00000000000056cda805738fc4b5"
Archived-At: <https://mailarchive.ietf.org/arch/msg/doh/YL6jflfRe7e9vqSEZA2ZpwRmV90>
Subject: Re: [Doh] Suggestion on draft-ietf-doh-dns-over-https-13: Recommend DANE-TLS to authenticate the TLS-certificate
X-BeenThere: doh@ietf.org
X-Mailman-Version: 2.1.27
Precedence: list
List-Id: DNS Over HTTPS <doh.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/doh>, <mailto:doh-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/doh/>
List-Post: <mailto:doh@ietf.org>
List-Help: <mailto:doh-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/doh>, <mailto:doh-request@ietf.org?subject=subscribe>
X-List-Received-Date: Thu, 16 Aug 2018 16:16:41 -0000

On Thu, Aug 16, 2018 at 8:42 AM, Rene 'Renne' Bartsch, B.Sc. Informatics <
ietf=40bartschnet.de@dmarc.ietf.org> wrote:

>
>
> Am 16.08.2018 um 15:38 schrieb Eric Rescorla:
>
>>
>>
>> On Thu, Aug 16, 2018 at 1:13 AM, Rene 'Renne' Bartsch, B.Sc. Informatics
>> <ietf=40bartschnet.de@dmarc.ietf.org <mailto:ietf=40bartschnet.de@d
>> marc.ietf.org>> wrote:
>>
>>     Hi,
>>
>>     as TLS-certificates forged or obtained by devious means have become
>> common in MITM-attacks by intelligence and criminals
>>     I suggest to RECOMMEND authentication of the DoH-server
>> TLS-certificate via DANE-TLS (RFC 6698) in section 10 (Security
>> considerations).
>>
>>
>> I don't think we should make this change. Much of the value proposition
>> of DoH is that it's straightforward to run on top of existing HTTPS
>> infrastructure, and as a practical matter nearly all of that infrastructure
>> depends on WebPKI certs and does not do DANE. For that reason, this
>> recommendation would be more aspirational than practical.
>>
>
> The problem I see is that e.g. firewall appliances with fake certificates
> by intermediate certificates can break privacy and manipulate the DNS
> records.
>

if you are behind such a firewall, you have much bigger problems than fake
DNS records, given that the traffic you are sending post-resolution is
almost certainly being protected with something rooted in the WebPKI.


Without proper authentication of the DoH-server certificate DoH only
> protects from script-kiddies.
>

I don't think it's accurate to characterize WebPKI as not "proper
authentication". That's certainly not the position we've taken elsewhere in
the IETF.

If you want to make some broader argument about how we should stop trusting
WebPKI and universally recommend DANE instead, you're welcome to do so, but
this particular document is mostly just an other application of HTTPS, so
it's really not the place for it.

-Ekr



>
> Renne
>
> _______________________________________________
> Doh mailing list
> Doh@ietf.org
> https://www.ietf.org/mailman/listinfo/doh
>

v2.23.0 | Report a Bug | By Email