[secdir] SecDir review of draft-ietf-dnsop-negative-trust-anchors-10

Yaron Sheffer <yaronf.ietf@gmail.com> Fri, 19 June 2015 20:24 UTC

Return-Path: <yaronf.ietf@gmail.com>
X-Original-To: secdir@ietfa.amsl.com
Delivered-To: secdir@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 1A0DE1B2A19; Fri, 19 Jun 2015 13:24:36 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -0.101
X-Spam-Level:
X-Spam-Status: No, score=-0.101 tagged_above=-999 required=5 tests=[BAYES_20=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, FREEMAIL_FROM=0.001, SPF_PASS=-0.001] autolearn=ham
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 xOQ4CeK3IOlo; Fri, 19 Jun 2015 13:24:34 -0700 (PDT)
Received: from mail-wg0-x22b.google.com (mail-wg0-x22b.google.com [IPv6:2a00:1450:400c:c00::22b]) (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 4ABC81B2A16; Fri, 19 Jun 2015 13:24:34 -0700 (PDT)
Received: by wgbhy7 with SMTP id hy7so98116412wgb.2; Fri, 19 Jun 2015 13:24:33 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:subject :content-type:content-transfer-encoding; bh=LMoRhoPSAFeI7oGOtxCwpzvnzpjQBo/H/2hfrp7YC4Q=; b=sSXIKFYf5plI7m476NIURmTGd3wbL/WxWTmUr3ggkWnpyO3OUvs+YLlwuZqhF7Ipy4 0HWFldcHs4Jowed8yMGfcD8tVIyfOzoKwEuaP+1LcmMXjHa4AcvZMQJqVXMS0cLvSrQQ EXtIT5pfiqfcg/yItIBsocF8f/U4VLqCczn6udtOhCX5tLUfhzchH7TUZmwk81fdawYH VFLiYdyj36PXk86FWfw06svkzBsoPuvHkkKfTTDxDZB/TfmrpUpZguTjDk9cJK0JVxxl cCRgovdzKg/vn11h2wHUeyY+VIONglh+oAoyItsJ3ktuGUEI14+uSXKnG9OwCVkD94Lt DyRA==
X-Received: by 10.180.218.195 with SMTP id pi3mr9876972wic.71.1434745473067; Fri, 19 Jun 2015 13:24:33 -0700 (PDT)
Received: from [10.0.0.5] (bzq-79-180-17-102.red.bezeqint.net. [79.180.17.102]) by mx.google.com with ESMTPSA id a19sm5218363wiv.2.2015.06.19.13.24.31 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 19 Jun 2015 13:24:31 -0700 (PDT)
Message-ID: <55847A7D.9030504@gmail.com>
Date: Fri, 19 Jun 2015 23:24:29 +0300
From: Yaron Sheffer <yaronf.ietf@gmail.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0
MIME-Version: 1.0
To: IETF Security Directorate <secdir@ietf.org>, The IESG <iesg@ietf.org>, draft-ietf-dnsop-negative-trust-anchors.all@tools.ietf.org
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Archived-At: <http://mailarchive.ietf.org/arch/msg/secdir/YdfnZZjzLVcsWnk2gCAYsopeuLY>
Subject: [secdir] SecDir review of draft-ietf-dnsop-negative-trust-anchors-10
X-BeenThere: secdir@ietf.org
X-Mailman-Version: 2.1.15
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: <http://www.ietf.org/mail-archive/web/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: Fri, 19 Jun 2015 20:24:36 -0000

I have reviewed this document as part of the security directorate's
ongoing effort to review all IETF documents being processed by the IESG.
These comments were written primarily for the benefit of the security
area directors.  Document editors and WG chairs should treat these
comments just like any other last call comments.

This document defines a process where an ISP can declare that certain 
domain names (whose DNSSEC records are deemed misconfigured) are not 
covered by DNSSEC. The server then provides DNS resolution in response 
to client queries, where otherwise the server would have failed those 
queries.

Summary

This is more of a rant than a review, however it presents a security 
perspective that seems to be at odds with the operational-first 
perspective of the document.

Details

I am hearing that this is a controversial draft, and I can see why. The 
draft explains very well what motivates the proposed mechanism, and the 
motivation makes sense, especially if you are an ISP. But I think the 
draft gives excellent instructions on improving the security of an 
inherently problematic usage model.

As an individual or even as a company, the local ISP is not my friend. 
State-controlled ISPs in less developed countries have been known to 
steal traffic and fake certificates in order to attack their own 
subscribers. Commercial ISPs in more developed countries throttle or 
block certain types of traffic for various reasons. Moreover, the local 
ISP is best positioned to identify the owner of individual IP endpoints 
and perform point attacks on local subscribers. DNS is an obvious attack 
vector.

Even assuming that 99.9% of us will continue to trust ISPs for DNS 
resolution, IMHO the proposed solution would be better off with more 
automation and less celebration of "trained technical personnel". For 
example, the document has a SHOULD level requirement to test the NTA 
"periodically" in order to eventually remove it. How about an 
alternative that shifts the responsibility to DevOps or to the actual 
vendors, and also empowers the .1% who maintain their own resolvers:

"NTA implementors MUST attempt to validate the domain in question once 
every MINUTE for the period of time that the Negative Trust Anchor is in 
place, until such validation is again successful, and MUST remove the 
NTA as soon as that happens."

Similarly, I would guess the process of establishing an NTA could be 
automated, e.g. by querying multiple major DNS operators over a period 
of time (maybe operators that are known to run the same brand of 
resolver). In general, automating the process is more likely to 
encourage deployment of DNSSEC by smaller ISPs than adding complex 
manual "best practices".

Thanks,
	Yaron