Re: [secdir] [taugh.com-standards] Re:Security review of draft-levine-herkula-oneclick-05

"John R. Levine" <johnl@iecc.com> Sun, 18 September 2016 23:36 UTC

Return-Path: <johnl@iecc.com>
X-Original-To: secdir@ietfa.amsl.com
Delivered-To: secdir@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 8F36812B034 for <secdir@ietfa.amsl.com>; Sun, 18 Sep 2016 16:36:05 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.001
X-Spam-Level:
X-Spam-Status: No, score=-2.001 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001] autolearn=unavailable autolearn_force=no
Authentication-Results: ietfa.amsl.com (amavisd-new); dkim=pass (1536-bit key) header.d=iecc.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 VZMbxT3i5xGi for <secdir@ietfa.amsl.com>; Sun, 18 Sep 2016 16:36:02 -0700 (PDT)
Received: from miucha.iecc.com (abusenet-1-pt.tunnel.tserv4.nyc4.ipv6.he.net [IPv6:2001:470:1f06:1126::2]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id A503212B046 for <secdir@ietf.org>; Sun, 18 Sep 2016 16:36:02 -0700 (PDT)
Received: (qmail 76189 invoked from network); 18 Sep 2016 23:35:59 -0000
DKIM-Signature: v=1; a=rsa-sha256; c=simple; d=iecc.com; h=date:message-id:from:to:cc:subject:in-reply-to:references:mime-version:content-type:user-agent; s=1299c.57df24df.k1609; bh=o/tFmo5SWWa7VPDml56pZj0k938beLc1pjUV2bkZK6Q=; b=v3cyjIwwoBq+MDBFum9kt5e5yRQHBk8xoSGkX7fQ70iGulDCrN1FxuLdy6EeL4go2kyBQiuh+bVafLqo4ZPH+vjIRDXL2W9TBZ66LBSm8kuGlB8NUxWu7QoNyx5sG8fOmktjK7wfiuubObcjblnStR4hXPCy5JlA+wbd5QPpsr0hSKr7JdZq00pANwX9NQUTBfZs6un8eG/I18WdO+BoAjIDZRUPMO6U9dg/3zKzW+i4Y3TzL6TaGSYIMDTRqHH9
Received: from localhost ([IPv6:2001:470:1f07:1126::78:696d:6170]) by imap.iecc.com ([IPv6:2001:470:1f07:1126::78:696d:6170]) with ESMTPS (TLS1.0/X.509/SHA1) via TCP6; 18 Sep 2016 23:35:59 -0000
Date: Sun, 18 Sep 2016 19:36:00 -0400
Message-ID: <alpine.OSX.2.11.1609181934050.6785@ary.lan>
From: "John R. Levine" <johnl@iecc.com>
To: Ben Laurie <benl@google.com>
In-Reply-To: <alpine.OSX.2.11.1609181337320.4957@ary.lan>
References: <CABrd9SQt9K+78WOm9aO_fObrvThKCVKyXAVF6WVmm=bN8c9bvw@mail.gmail.com> <alpine.OSX.2.11.1609181216340.4398@ary.lan> <CABrd9SSFCb7XdVFmLW6-OAtoo_7d-=Uivq0ax2v6iJKx=TusUg@mail.gmail.com> <alpine.OSX.2.11.1609181306500.4660@ary.lan> <CABrd9SQNM2e3AJwLSgzXV54MzKRf0MZ9_E+GPaT2oCzFwajdpQ@mail.gmail.com> <alpine.OSX.2.11.1609181337320.4957@ary.lan>
User-Agent: Alpine 2.11 (OSX 23 2013-08-11)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset="US-ASCII"; format="flowed"
Archived-At: <https://mailarchive.ietf.org/arch/msg/secdir/cr5QAHlIsTYK2yUmxYTEGiegi6I>
Cc: Paul Kincaid-Smith <paulkincaidsmith@gmail.com>, The IESG <iesg@ietf.org>, Tobias Herkula <tobias.herkula@optivo.de>, "secdir@ietf.org" <secdir@ietf.org>
Subject: Re: [secdir] [taugh.com-standards] Re:Security review of draft-levine-herkula-oneclick-05
X-BeenThere: secdir@ietf.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: Security Area Directorate <secdir.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/secdir>, <mailto:secdir-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/secdir/>
List-Post: <mailto:secdir@ietf.org>
List-Help: <mailto:secdir-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/secdir>, <mailto:secdir-request@ietf.org?subject=subscribe>
X-List-Received-Date: Sun, 18 Sep 2016 23:36:05 -0000

One other thought -- I think the most common thing that mailers do is to 
put the subscriber info into a database where each record includes a 
randomly generated key unrelated to anything else.  Then you put that key 
into the URI, no HMAC needed.

R's,
John

>>> It's only a goal here because they have other ways to do it if it's not
>>> one-click.
>> 
>> Ok, then in that case it seems like you only need to secure the POST
>> arguments, not the URI.
>
> There's several scenarios that this draft is addressing:
>
> A) bad guy sends fake mail with real insecure opt-out link, MUA clicks it
> indirectly when user hits the junk button
>
> B) real message with real link is clicked by helpful anti-spam software, not 
> the user
>
> The hash stuff is for A, the POST is for B.  Since the POST gets both the URI 
> and the arguments, the hash can be in whichever is operationally easier.  All 
> the places that have rules about commercial junk mail say that if the 
> recipient tells you to stop, you have to stop and "the link was in a fake 
> message" isn't a defense. It's quite common now for the unsubscribe URI to be 
> totally opaque, e.g., with a hash and a key the mailer looks up in a database 
> to find the recipient's address, so that malicious parties can't guess other 
> subscribers' addresses.  If they add POST arguments for one-click, they'll 
> likely keep the existing opaque URI, and with the secure URI, the POST 
> arguments tell it nothing beyond the fact that this is a one-click 
> transaction.
>
> In the two decades since 2369 came out, the URI stuff has become common 
> knowledge among the narrow group of people for whom "deliverability" is an 
> adjective.  I really don't want to open up 2369 with this draft, because I 
> don't think the small amount this draft says would be helpful.  It doesn't 
> change the way people use 2369, it only adds a new way to do 
> list-unsubscribe.

Regards,
John Levine, johnl@iecc.com, Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. https://jl.ly