[Servercert-wg] Discussion Period Begins - Ballot SC-080 V1: "Sunsetting use of WHOIS to identify Domain Contacts"

Tue Sep 24 16:42:09 UTC 2024

Hi Ryan,

Both of these objectives are valuable outcomes to pursue, from my perspective. Regarding Objective 2, I think a shorter timeline for an effective date is desirable, especially in relation to 3.2.2.4.2’s inclusion of Fax, SMS, and Postal Mail as communication mediums for domain validation. I would suggest July 15, 2025 as a reasonable date which still meets the criteria you provided, excepting that it doesn’t match an effective date already present in the TBRs. Other than that, I think these objectives and the overall proposal are sound and provide demonstrable improvement to the overall security of domain validation. Thank you for spearheading this!

Cheers,
-Clint

> On Sep 23, 2024, at 12:48 PM, Ryan Dickson via Servercert-wg <servercert-wg at cabforum.org> wrote:
> 
> [Responding to the most recent message in the discussion, apologies if this causes unexpected threading.]
> 
> Hi all,
> 
> Given the discussion thus far, I’d like to propose the following for the group’s consideration in an effort to help guide a second round of discussion (TBD, but expected to begin no earlier than September 30).
> 
> Objective 1: Enhance WHOIS/RDAP validation of gTLDs with comparable security properties to DNS-based validation and sunset WHOIS/RDAP for ccTLDs.
> 
> Justification:
> A recent disclosure [1] demonstrated how threat actors could exploit deficiencies in the WHOIS protocol and WHOIS tools served via HTTPS websites to obtain fraudulent TLS certificates.
> Discussions within the Mozilla Dev Security Policy (MDSP) community [2] further expressed corresponding risks related to WHOIS, while also noting that ccTLDs may not maintain accurate or up-to-date WHOIS server records. Several examples of inoperative WHOIS servers for ccTLDs were identified.
> Discussion in [3] further called into question the reliability of ccTLD WHOIS servers given, per IANA, there is no global policy requirement for ccTLD managers to operate a WHOIS server, and if they do, what kind of information is provided.
> Solutions to strengthen existing WHOIS lookup methods were proposed in [4] and are considered in this update.
> Approach:
> Add the following requirements in Sections 3.2.2.4.2 (“Email, Fax, SMS, or Postal Mail to Domain Contact”), 3.2.2.4.12 (“Validating Applicant as a Domain Contact”), and 3.2.2.4.15 (“Phone Contact with Domain Contact”).
> “Effective January 15, 2025, when issuing Subscriber Certificates…
> The CA MUST NOT rely on Domain Contact information obtained using an HTTPS website, regardless of whether previously obtained information is within the allowed reuse period.
> The CA MUST NOT rely on Domain Contact information obtained using the WHOIS protocol (RFC 3912) or the Registry Data Access Protocol (RFC 7482) if the requested Domain Name contains a ccTLD, regardless of whether previously obtained information is within the allowed reuse period.
> When obtaining Domain Contact information using the WHOIS protocol, the CA MUST query IANA's WHOIS server and follow referrals to the appropriate gTLD WHOIS server.
> When obtaining Domain Contact information using the Registry Data Access Protocol, the CA MUST utilize IANA's bootstrap file to identify and query the correct RDAP server for the domain.
> The CA SHOULD NOT rely on cached 1) WHOIS server information or 2) RDAP bootstrap data from IANA to ensure that it relies upon up-to-date and accurate information.”
> 
> Objective 2: Sunset Methods 3.2.2.4.2 (“Email, Fax, SMS, or Postal Mail to Domain Contact”) and 3.2.2.4.15 (“Phone Contact with Domain Contact”).
> 
> Justification:
> While solutions to strengthen WHOIS-relying DCV methods are considered in this update (above), there is limited public evidence of significant reliance on these methods, including in response to [2] and [5].
> Instead, discussion has identified at least one CA Owner has already sunset reliance on WHOIS [6], and another that has changed its approach [7] for relying on WHOIS since disclosure of [1].
> More modern and heavily relied-upon DCV methods offer advantages over the existing WHOIS-based methods, including greater opportunity for seamless certificate lifecycle management automation (e.g., [8] and [9]), while also benefiting from recently improved security practices [10]. These methods can also more effectively align subscriber capabilities with agility and resilience expectations necessary to respond to the revocation timelines described in the TLS BRs [11].
> Beyond the above, previous discussions within the CA/Browser Forum have raised concerns about the perceived value (e.g., [12]) and security (e.g., [13]) of the DCV methods relying on WHOIS, further supporting the rationale for their gradual sunset.
> Approach:
> Add the following requirements to Sections 3.2.2.4.2 (“Email, Fax, SMS, or Postal Mail to Domain Contact”) and 3.2.2.4.15 (“Phone Contact with Domain Contact”).
> “Effective September 15, 2025, the CA MUST NOT rely on this method.”
> 
> 
> The effective dates considered in this update are intended to 1) address the immediate concerns identified by [1], 2) offer near-term and longer-term transition periods for subscribers and CA Owners relying on existing implementations of these methods, and 3) align with existing effective dates in the TLS BRs (e.g., [10]).
> 
> The above proposed updates compared to the initial effort described in [14] are highlighted at [15]. A comparison of these proposed updates against the in-force BRs is available at [16]
> 
> Comments are welcome either on-list or with suggested edits via GitHub (preferred) at [17].
> 
> Thanks,
> Ryan
> 
> [1] https://labs.watchtowr.com/we-spent-20-to-achieve-rce-and-accidentally-became-the-admins-of-mobi/
> [2] https://groups.google.com/a/mozilla.org/g/dev-security-policy/c/FuOi_uhQB6U/m/hKJOz3XzAAAJ
> [3] https://groups.google.com/a/mozilla.org/g/dev-security-policy/c/mAl9XjieSkA/m/oDNWxtPwAQAJ
> [4] https://archive.cabforum.org/pipermail/servercert-wg/2024-September/004839.html
> [5] https://archive.cabforum.org/pipermail/servercert-wg/2024-September/004844.html
> [6] https://aws.amazon.com/blogs/security/aws-certificate-manager-will-discontinue-whois-lookup-for-email-validated-certificates/
> [7] https://bugzilla.mozilla.org/show_bug.cgi?id=1917896
> [8] https://cabforum.org/working-groups/server/baseline-requirements/requirements/#32247-dns-change
> [9] https://cabforum.org/working-groups/server/baseline-requirements/requirements/#322419-agreed-upon-change-to-website---acme
> [10] https://cabforum.org/working-groups/server/baseline-requirements/requirements/#3229-multi-perspective-issuance-corroboration
> [11] https://cabforum.org/working-groups/server/baseline-requirements/requirements/#491-circumstances-for-revocation
> [12] https://archive.cabforum.org/pipermail/servercert-wg/2018-August/000113.html
> [13] https://lists.cabforum.org/pipermail/validation/2024-July/001995.html
> [14] https://archive.cabforum.org/pipermail/servercert-wg/2024-September/004825.html
> [15] https://github.com/ryancdickson/staging/compare/356799f0dcfe11deb0a375a11233403236ab72c9..7a2ea7b33611bebf006a99a9a82729f183143eac
> [16] https://github.com/ryancdickson/staging/compare/ba28d04894d69c8fac62850b9d0de5061658c7c5..7a2ea7b33611bebf006a99a9a82729f183143eac
> [17] https://github.com/ryancdickson/staging/pull/9
> 
> 
> On Wed, Sep 18, 2024 at 3:11 PM Amir Omidi via Servercert-wg <servercert-wg at cabforum.org <mailto:servercert-wg at cabforum.org>> wrote:
>> I do not know much about the state of subdomain auth deployment in the CA ecosystem unfortunately.
>> 
>> On Wed, Sep 18, 2024 at 2:09 PM Andrew Ayer <agwa at andrewayer.name <mailto:agwa at andrewayer.name>> wrote:
>>> Hi Amir,
>>> 
>>> On Wed, 18 Sep 2024 15:48:38 +0000
>>> Amir Omidi via Servercert-wg <servercert-wg at cabforum.org <mailto:servercert-wg at cabforum.org>> wrote:
>>> 
>>> > There are two CAs (Let's Encrypt and Google Trust Services) with
>>> > DNS-ACCOUNT-01 (
>>> > https://datatracker.ietf.org/doc/draft-ietf-acme-scoped-dns-challenges/)
>>> > mostly ready to go. This draft is designed to solve the CNAME
>>> > delegation problem.
>>> 
>>> It doesn't obviate the need to run an acme-dns server (or similar) but
>>> DNS-ACCOUNT-01 would indeed be a great help.  Note that RFC9444
>>> (subdomain auth) support is also needed as otherwise the subscriber
>>> has to add delegations for every hostname instead of just one per zone.
>>> Do you know what the state of CA adoption is there?
>>> 
>>> In any case, I'll give this I-D a more thorough look and provide
>>> feedback in the ACME WG.
>>> 
>>> Regards,
>>> Andrew
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