[Servercert-wg] Discussion Period Begins - Ballot SC-067 V3: "Require domain validation and CAA checks to be performed from multiple Network Perspectives"

Mon May 20 14:29:00 UTC 2024

Purpose of Ballot SC-067 V3:

This Ballot proposes updates to the Baseline Requirements for the Issuance
and Management of Publicly-Trusted TLS Server Certificates (i.e., TLS BRs)
related to “Multi-Perspective Issuance Corroboration” (“MPIC”).

Background:

- MPIC refers to performing domain validation and CAA checks from multiple
Network Perspectives before certificate issuance, as described within the
Ballot for the applicable validation methods in TLS BR Sections 3.2.2.4 and
3.2.2.5.

- Not all methods described in TLS BR Sections 3.2.2.4 and 3.2.2.5 will
require using MPIC.

- This work was most recently motivated by research presented at
Face-to-Face 58 [1] by Princeton University, but has been discussed for
years prior as well.

- The goal of this proposal is to make it more difficult for adversaries to
successfully launch equally-specific prefix attacks against the domain
validation processes described in the TLS BRs.

- Additional background information can be found in an update shared at
Face-to-Face 60 [2].

Benefits of Adoption:

- Recent publicly-documented attacks have used BGP hijacks to fool domain
control validation and obtain malicious certificates, which led to the
impersonation of HTTPS websites [3][4].

- Routing security defenses (e.g., RPKI) can mitigate the risk of global
BGP attacks, but localized, equally-specific BGP attacks still pose a
significant threat to the Web PKI [5][6].

- Corroborating domain control validation checks from multiple network
perspectives (i.e., MPIC) spread across the Internet substantially reduces
the threat posed by equally-specific BGP attacks, ensuring the integrity of
domain validation and issuance decisions [5][7][8].

- Existing deployments of MPIC at the scale of millions of certificates a
day demonstrate the feasibility of this technique at Internet scale [7][9].

Intellectual Property (IP) Disclosure:

- While not a Server Certificate Working Group Member, researchers from
Princeton University presented at Face-to-Face 58, provided academic
expertise, and highlighted publicly-available peer-reviewed research to
support Members in drafting this ballot.

- The Princeton University researchers indicate that they have not filed
for any patents relating to their MPIC work and do not plan to do so in the
future.

- Princeton University has indicated that it is unable to agree to the
CA/Browser Forum IPR agreement because it could encumber inventions
invented by researchers not involved in the development of MPIC or with the
CA/B Forum.

- Princeton University has instead provided the attached IPR statement.
Pursuant to the IPR statement, Princeton University has granted a worldwide
royalty free license to the intellectual property in MPIC developed by the
researchers and has made representations regarding its lack of knowledge of
any other Princeton intellectual property needed to implement MPIC.

- The attached IPR statement has not changed since disclosed in Discussion
Round 1.

- For clarity, Princeton University’s IPR statement is NOT intended to
replace the Forum’s IPR agreement or allow Princeton to participate in the
Forum in any capacity.

- Members seeking legal advice regarding this ballot should consult their
own counsel.

Proposal Revision History:

- Pre-Ballot Release #1 (work team artifacts and broader Validation
Subcommittee collaboration) [10]

- Pre-Ballot Release #2 [11]

Previous versions of this Ballot:

- Ballot Release #1 [12] (comparing Version 2 to Version 1) [13]. Note,
some of the changes represented in the comparison are updates made by other
ballots that have since passed (e.g., SC-069).

- Ballot Release #2 [14] (comparing Version 3 to Version 2) [15]. Note,
some of the changes represented in the comparison are updates made by other
ballots that have since passed (e.g., SC-072).

References:

[1]
https://cabforum.org/wp-content/uploads/13-CAB-Forum-face-to-face-multiple-vantage-points.pdf

[2]
https://drive.google.com/file/d/1LTwtAwHXcSaPVSsqKQztNJrV2ozHJ7ZL/view?usp=drive_link

[3]
https://medium.com/s2wblog/post-mortem-of-klayswap-incident-through-bgp-hijacking-en-3ed7e33de600

[4] https://www.coinbase.com/blog/celer-bridge-incident-analysis

[5]
https://www.usenix.org/conference/usenixsecurity23/presentation/cimaszewski

[6]
https://www.blackhat.com/docs/us-15/materials/us-15-Gavrichenkov-Breaking-HTTPS-With-BGP-Hijacking-wp.pdf

[7]
https://www.usenix.org/conference/usenixsecurity21/presentation/birge-lee

[8]
https://www.usenix.org/conference/usenixsecurity18/presentation/birge-lee

[9]
https://security.googleblog.com/2023/05/google-trust-services-acme-api_0503894189.html

[10] https://github.com/ryancdickson/staging/pull/6

[11] https://github.com/ryancdickson/staging/pull/8

[12] https://github.com/cabforum/servercert/pull/487

[13]
https://github.com/cabforum/servercert/compare/6d10abda8980c6eb941987d3fc26e753e62858c0..5224983ef0a6f94c18808ea3469e7a5ae35746e5

[14] https://github.com/cabforum/servercert/pull/507

[15]
https://github.com/cabforum/servercert/compare/5224983ef0a6f94c18808ea3469e7a5ae35746e5..2dcf1a8fe5fc7b6a864b5767ab1db718bc447463

The following motion has been proposed by Chris Clements and Ryan Dickson
of Google (Chrome Root Program) and endorsed by Aaron Gable (ISRG / Let’s
Encrypt) and Wayne Thayer (Fastly).

— Motion Begins —

This ballot modifies the “Baseline Requirements for the Issuance and
Management of Publicly-Trusted TLS Server Certificates” (“Baseline
Requirements”), based on Version 2.0.4.

MODIFY the Baseline Requirements as specified in the following Redline:

https://github.com/cabforum/servercert/compare/c4a34fe2292022e0a04ba66b5a85df75907ac2a2..2dcf1a8fe5fc7b6a864b5767ab1db718bc447463

— Motion Ends —

This ballot proposes a Final Maintenance Guideline. The procedure for
approval of this ballot is as follows:

Discussion (at least 11 days)

- Start: 2024-05-20 14:30:00 UTC

- End no earlier than: 2024-05-31 14:30:00 UTC

Vote for approval (7 days)

- Start: TBD

- End: TBD
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