[Servercert-wg] [cabf_validation] Underscores, DNSNames, and SRVNames

Wayne Thayer wthayer at mozilla.com
Tue Oct 23 09:52:04 MST 2018

On Tue, Oct 23, 2018 at 9:47 AM Ryan Sleevi <sleevi at google.com> wrote:

> On Mon, Oct 22, 2018 at 7:36 PM Wayne Thayer <wthayer at mozilla.com> wrote:
>> On Tue, Oct 23, 2018 at 6:33 AM Ryan Sleevi <sleevi at google.com> wrote:
>>> Given the data I've shared, do you feel that it's still an accurate
>>> statement to suggest there's any "pain" at all, or that there are any
>>> bureaucratic change management processes involved?
>> Given the data that you shared, please explain how you reach the
>> conclusion that there is zero "pain" for Subscribers?
> Sure. When a mosquito bites me, I don't treat it like kidney stones. And I
> make a distinction between eating ice cream really fast and having my teeth
> sensitive versus having my appendix removed. It's not that there's
> "nothing" felt, it's that there's no pain - to suggest that the
> inconvenience, on an ecosystem level, represents 'pain' is to undermine
> much of the real pain that exists in the ecosystem.
> While I know CAs have been very attune to "no customer left behind", every
> ecosystem maintainer in the Forum has generally acknowledge that "no"
> impact is not a reasonable goal, and "minimal" impact is acceptable. My
> point of sharing those numbers was to show that talking about it being
> painful is a bit like being a professional soccer player [1][2]. It's
> entertaining, but it's not exactly furthering the industry.
> I think the question here, at the core of this discussion, is how much
> 'pain' is acceptable. Is 3955 certificates? Is it the 3238 distinct
> hostnames represented in those certificates? Is it the 216 certificates,
> representing 166 domain names, that can't be transitioned to wildcards
> tomorrow? Does factoring in revocations and distrust matter? What's the
> threshold at which we say that it's more important to deliberately
> introduce incompatibility into the ecosystem? And who should decide? The
> browsers? The CAs? The public? In those same logs, we see 252,675,924
> distinct DNS names and 1,187,938,671 certificates. Are those numbers
> inflated due to revocations, distrust, and non-publicly-trusted CAs
> included - but considering that the same applies to those previous numbers,
> it's at least a consistent measure - and a hard upper bound.
> It should be clear my view that standards exist to provide a reliable and
> interoperable system that allows for competitors to work together to build
> interoperable systems, to provide a consistent baseline for those seeking
> to understand and address security concerns. That the Forum should not be
> in the business of circumventing multi-stakeholder models, whether that
> multi-stakeholder model is the Mozilla Dev.Security.Policy community that
> allows far greater representation than the Forum, or the IETF
> consensus-building process. The moment we, as a Forum, start pursuing that
> path, we sacrifice the legitimacy of the Forum and the safety afforded to
> our collaborations.
> [1]
> https://www.buzzfeed.com/mjkiebus/ridiculous-soccer-dives-guaranteed-to-make-you-angry
> [2]
> https://www.theatlantic.com/entertainment/archive/2014/06/dissecting-american-soccers-hatred-of-the-flop-is-a-world-cup-tradition/372839/
>> I think we disagree, then. By failing to adopt an immediate sunset -
>>> which I believe the data does not support - this encourages CAs to reissue
>>> certificates with the prolonged period sooner for their customers, "just in
>>> case". This then creates more migration pain, as customers will have 2+
>>> year certificates, and fail to actually transition until their current
>>> certificate expires.
>>> I am explicitly attempting to prevent this type of behavior by requiring
>> that all certificates with a lifetime > 30 days be revoked prior to 1-June.
>> Are you dismissing revocation as an effective tool for blocking the use of
>> these certificates (presumably they would need to be added to a CRLSet), or
>> is there some other problem with this approach?
> I believe this approach is fundamentally flawed, and that we have ample
> evidence to know that this does not lead to the desired result. The desired
> result of any later sunset is to say "Organizations need time to adapt, and
> by delaying impact, we give them time to move." In every single attempt
> that the Forum, or its representative Browser members have done it, it has
> not worked out like that. It's foolish to think this will be different.
> What happens - and we see this consistently, whether we talk RSA-1024,
> SHA-1, internal server names, or multi-staged CA deprecations - is that
> until the impact is actually experienced, no preparations are made.
> Further, we see disingenuous behaviour by both CAs and other browsers, by
> suggesting that since it's not "yet" sunset, any premature action (such as
> adding to OneCRL or changing UI) is somehow going against the "consensus"
> of the industry - as if the Forum sets acceptable standards, rather than
> minimal.
> The benefit of an immediate reduction in time, and shortly thereafter,
> revocation-and-replacement, is that it actually sets up a sustainable
> method of alerting certificate holders to the need to replace, while
> allowing them time to transition. There's no ambiguity in the ecosystem if
> you have to replace your existing (2020 hypothetically, but in practice far
> shorter) certificate with something to 30 days. And to periodically replace
> it. There's no question that there's a frequent reminder that change is
> coming and is necessary, and allowing organizations to make the
> cost/benefit analysis. The approach proposed - whether for this or for any
> other deprecation - is to create an expense that goes from 0 (nothing
> wrong) to total (time to replace). No amount of preparation - years even -
> has been shown to work in the ecosystem, while rather consistently,
> expiration dates have proven a means to effectively moving the ecosystem
> forward.
> I think we are mostly in agreement here, but from the tone of your
comments, either my original proposal is flawed in this regard, or you
don't understand it. While I provided some time (~6 months) before
requiring revocation and restricting lifetimes to 30-days, the intent was
to avoid the "cliff" that has plagued previous sunsets by forcing
Subscribers to short-lived certificates.

We'd be fooling ourselves to approach deprecations in the future as
> anything other than "immediate" reduction in lifetime to address the issue
> going forward, and "soon" thereafter, bringing the existing body of
> certificates (and their holders) into that same cost/benefit analysis
> discussion through revocation. If there's something new to try here, I'm
> all ears, but let's not think our past failures will somehow be fixed by
> doing the exact same thing.
>> Can you explain how we're discussing anything but that? We've expended
>>> significant energy for what accounts for a dozen or so organizations. We
>>> have data to know the scope of the problem and the impact, and its
>>> practical reality.
>>> Given that the impact is so small, perhaps a better solution is to stop
>> debating this and for you to file a bug to block these certificates in
>> Chromium. Seriously - that would satisfy my primary goal here.
> Because that approach is to fundamentally make the CA/Browser Forum
> useless, both philosophically and practically. If the goal is to serve as a
> Forum to avoid conflicting program requirements, by establishing common
> Baselines, then it provides no value if the Forum is going to retroactively
> grant indulgences depending on how widespread the issue is. It's actively
> hostile to our European CAs bound by Regulation (EU) No 910/2014 - they
> don't have the luxury of getting to pick and choose which parts of RFC 5280
> to ignore like our WebTrust-audited friends do. It suggests that the
> approach to deal with interoperability is to externally regulate, that the
> Forum itself is not capable of defining or implementing interoperable
> standards. As an approach to risk, it shows an aversion that is an extreme
> - at best, setting a goal of "zero" impact, an impossible to achieve and
> harmful to the ecosystem level. And if that's not the level we're setting,
> then we're no longer acting on principles, and instead arbitrarily.
> For all the CAs not participating in the Forum, who don't get to vote to
> retroactively bless themselves, and to all the CAs who do participate in
> the Forum, and have stopped the practice, it suggests that the Baseline
> Requirements are a way to keep CAs out (since to vote, they have to comply,
> while existing voting members are being allowed to be non-compliant). It
> suggests the Baseline Requirements aren't really Requirements, they're the
> "Baseline hints for things we'd really like you to follow, but if you have
> customers who want certificates that don't comply, I guess that's OK too"
> For the browsers who would vote in favor of this, it seems like a way for
> browsers to add more barriers for new competition. The point of standards
> is to make it easier to develop interoperability. Want to see how that bit
> Mozilla? https://bugzilla.mozilla.org/show_bug.cgi?id=1136616 or
> https://bugzilla.mozilla.org/show_bug.cgi?id=479520#c45 or
> https://bugzilla.mozilla.org/show_bug.cgi?id=354493#c198 . The ecosystem
> "works" when it's not a giant ball of hacks, which is why we browsers have
> such productive relationships trying to actually align on standards
> behaviour (and define standards where appropriate) - so that developers can
> have a reliable and consistent experience, whether writing a browser or
> writing for the Web.
>> Perhaps you can help me understand how this is different than, for
>>> example, Symantec's issuance of multiple BR violating certificates -
>>> https://bugzilla.mozilla.org/show_bug.cgi?id=966350 - and a process of
>>> retroactive indulgences?
>> It sounds like you are focused on the behavior of the CAs, and I'm
>> focused on the behavior of the Subscribers. Thinking about the SHA-1
>> sunset, I don't want Subscribers to have any hope of getting an exception.
> But isn't that exactly what's being proposed? Automatic exceptions before
> May, and after May, exceptions only so long as it's less than 45 days (as
> proposed). It doesn't actually define any sunset - and it's not about
> changing requirements, because they're requirements that have always
> existed.
>> If the goal is to find compromise, then it seems more reasonable to focus
>>> on "Which organizations cannot switch to a wildcard certificate tomorrow"
>> MY goal is to find a compromise - Your goal is not clear to me, and you
>> didn't answer my request for specific guidance. Would a ballot that
>> "immediately" forbids issuance of these certificates with validity periods
>> of greater than 30 days be the basis for an acceptable compromise? If not,
>> is that because you don't believe that any acceptable compromise exists?
> I had thought we walked out of Shanghai with a reasonable path forward to
> meaningfully not throwing the ecosystem - and the Forum - under the bus.
> 1) Immediate reduction in lifetime
> 2) Complete disclosure of any existing certificates not yet disclosed, to
> measure compliance with #3 and to assist #4.
> 3) "Soon" a complete revocation of existing certificates. The suggestion
> was "3 months".
> 4) A "whitelist" for any domains that cannot be met by existing,
> permitted, compatible practice (underscores other than in the left-most
> label). As the data shows, the practical impact of such a whitelist is, at
> an upper-bound, 166 certificates based on the currently disclosed practice,
> but as a practical matter, is actually much smaller. Just from looking at
> the list I provided, it appears that up to a third of those may have been
> automated systems and/or mistakes.
> 5) Issuance is *only* permitted for #4 above, and consistent with #1.
> These are the only certificates that can't be simply replaced with wildcard
> certificates.
> 6) Complete sunset <= 1y.
> I'm still struggling to understand why a whitelist is necessary. The
obvious reason would be to prevent new FQDNs from adding to the problem,
but given the limited scope of the problem to begin with and the 30-day
validity requirement, I can't imagine that we're talking about more than a
handful of certificates with "new" (not whitelisted) names. In contrast,
there are practical questions (how is it compiled? Where is it published?
How is it enforced?) that make a whitelist undesirable. If we have already
spent more time on this problem than it merits, why should we put in the
additional effort to define a whitelisting process?

Otherwise, I think the following ballot language captures your requirements:

Prior to October 1, 2019, certificates containing underscore characters
(“_”) in domain labels in DNSName entries MAY be issued as follows:
* DNSName entries MAY include underscore characters in the left most domain
label such that replacing all underscore characters with hyphen characters
(“-“) would result in a valid domain label, and;
* Such certificates MUST NOT be valid for longer than 30 days.

All certificates containing an underscore character in any DNSName entry
and having a validity period of more than 30 days MUST be revoked prior to
March 1, 2019.

After October 31, 2019, underscore characters (“_”) MUST NOT be present in
DNSName entries.


The choice of #3 is when the ecosystem will finally "start" to move.
> Delaying #1 or #4 just makes #3 worse for the ecosystem, and doesn't really
> move the needle forward in reducing impact or risk.
> Breaking this down by DV/OV/EV and distinct names, we see the following:
> count subject_organization
> 1251 vIPtela Inc
> 282 null
> 151 CVS / Pharmacy
> 122 CVS Pharmacy Inc
> 104 Northern Trust Company
> 80 verizon wireless
> 69 Citigroup Inc.
> 50 The Northern Trust Company
> 42 Vodafone Group Services Limited
> Breaking it down by names that have an underscore somewhere else than the
> leftmost label, we see something more mundane:
> count subject_organization
> 59 null
> 7 TOYOTA Connected Corporation
> 6 Aviva PLC
> 5 Daum Assecuranz KG Versicherungsmakler
> 4 Citigroup Inc.
> 4 Microsoft Corporation
> 4 verizon wireless
> 3 Omgeo
> 3 PTFS, Inc.
> 3 HP Inc
> If we assume each of those DV certificates (those "null") represents a
> totally different account (which, I mean, I can keep digging into data to
> show that such an assumption is not correct, because of shared ADNs),
> that's still a "solvable" level of human contact to talk to, and that the
> impact on the actual names and the effort the Subscriber needs to take is
> bounded.
> That subset shows its a far fewer set of names, many of which themselves
>>> are no longer valid domains (demonstrably not in use nor possible to) and
>>> makes it clear that we're spending all this time for a few dozen
>>> organizations. Which is to say it's a whitelist, it's an exception process,
>>> and it's one that directly benefits a few CAs and a few organizations, yet
>>> with existential risk to the legitimacy of the Forum, the Baseline
>>> Requirements, and the neutrality of the Forum.
>> To the extent that a whitelist benefits CAs who have continued to - or
>> recently discontinued - issuance of these certificates, I agree that a
>> whitelist is biased and thus shouldn't be pursued.
> I think it's rather the inverse. Anything other than a whitelist is to
> suggest that if you do enough of something, you can continue doing it, and
> anyone who stops is prematurely penalized. The whitelist prevents further
> profiteering from those negligent and incorrect CAs.
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