Hi ChyaHung Tsai. Firstly, I'd like to commend TWCA for its prompt attention
to this matter and for seeking to understand what needs to be addressed.
> Maybe our Cross‑Certified Subordinate CA Certificate (TWCA Global Root to
> TWCA CYBER Root) does not include an EKU, which causes the program to also
> identify TWCA CYBER Root as having the capability to issue S/MIME (inheriting
> the capabilities of TWCA Global Root)?
Yes, that's correct.
> Additionally, our S/MIME audit report includes this Cross‑Certified
> Subordinate CA Certificate, but does not include the self‑signed TWCA CYBER
> Root, because that TWCA CYBER Root does not have the mail trust bit, and
> therefore the "Audits Same as Parent" flag does not apply.
MRSP 5.3 says "All certificates that are capable of being used to issue new
certificates and that directly or transitively chain to a CA certificate
included in Mozilla’s root store MUST be operated in accordance with this
policy."
The self-signed TWCA CYBER Root certificate "chain[s] to a CA certificate
included in Mozilla's root store" that has the Email trust bit enabled, and so
it "MUST be operated in accordance with" the S/MIME provisions of the MRSP.
It's a suboptimal chain, but it is nonetheless a valid chain:
TWCA Global Root
-> TWCA CYBER Root (cross-certificate)
-> TWCA CYBER Root (self-signed certificate)
-> Intermediate CA Certificate
-> Leaf Certificate
> 6. We have noticed warnings regarding CRL expiration, but after verifying the
> CRLs downloaded from the CDP, they all appear to be valid. Could you confirm?
You're correct that unexpired CRLs are being returned in response to
Unconditional GET requests.
Example:
$ wget -nv "http://RootCA.twca.com.tw/TWCARCA/cyber_root_revoke_2022.crl"; -O
/dev/stdout | openssl crl -inform der -lastupdate -nextupdate -noout
2025-03-06 14:43:17
URL:http://rootca.twca.com.tw/TWCARCA/cyber_root_revoke_2022.crl [719/719] ->
"/dev/stdout" [1]
lastUpdate=Mar 6 09:00:00 2025 GMT
nextUpdate=Mar 7 08:59:59 2025 GMT
Expired CRLs are being flagged because TWCA's CRL server is responding
incorrectly to the Conditional GET requests that crt.sh's crl_monitor sends.
Example:
$ wget -nv --header="If-Modified-Since: Wed, 30 Jun 2024 21:00:00 GMT"
"http://RootCA.twca.com.tw/TWCARCA/cyber_root_revoke_2022.crl";
http://rootca.twca.com.tw/TWCARCA/cyber_root_revoke_2022.crl:
2025-03-06 14:38:40 ERROR 304: Not Modified.
________________________________
From: Chya-Hung Tsai <[email protected]>
Sent: 06 March 2025 03:44
To: CCADB Public <[email protected]>
Cc: Ben Wilson <[email protected]>; [email protected] <[email protected]>;
Rob Stradling <[email protected]>
Subject: Re: Missing or Inconsistent Disclosure of S/MIME BR Audits
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Dear Ben,
Maybe our Cross‑Certified Subordinate CA Certificate (TWCA Global Root to TWCA
CYBER Root) does not include an EKU, which causes the program to also identify
TWCA CYBER Root as having the capability to issue S/MIME (inheriting the
capabilities of TWCA Global Root)?
Additionally, our S/MIME audit report includes this Cross‑Certified Subordinate
CA Certificate, but does not include the self‑signed TWCA CYBER Root, because
that TWCA CYBER Root does not have the mail trust bit, and therefore the
"Audits Same as Parent" flag does not apply.
ChyaHung Tsai
TWCA
Ben Wilson 在 2025年3月6日 星期四上午10:45:39 [UTC+8] 的信中寫道：
Dear ChyaHung Tsai,
Could these alerts be due to the cross-signing of the roots by the TWCA Global
Root CA?
In the CCADB, both of these roots also appear as subordinate CAs because they
are signed by the TWCA Global Root CA (it doesn't matter that they are called
"roots"), so they would inherit the trust of that root, which has both trust
bits indicated. I think that might be the reasoning.
I'm not sure about the expiring CRL you mention.
Ben
On Wednesday, March 5, 2025 at 6:30:51 PM UTC-7 [email protected] wrote:
Hi Rob,
Thank you for providing a summary of the S/MIME BR Audit disclosure status. On
behalf of TWCA, I would like to raise a few questions regarding the alerts on
https://crt.sh/mozilla-disclosures<https://urldefense.com/v3/__https://crt.sh/mozilla-disclosures__;!!J5K_pWsD!yasWOllrX91fE5MB_c22RVmjkVN3I1l_ArKr0Mj1LSpP3ggyCjbi89Rf1bnsQM1ch-O2oM39ojqOiw$>:
1. [Root] TWCA CYBER Root CA is a TLS-only certificate hierarchy. In CCADB,
the trust bits are only set for "website," but it appears as both "Server" and
"Email" in the report. Could you clarify why?
2. Following the previous point, since this Root CA does not issue S/MIME
certificates, it should not require an S/MIME Audit. Is this assumption correct?
3. [Root] TWCA Global Root CA G2 does not have TLS issuance capabilities. In
CCADB, the trust bits are only set for "email," but it is displayed as both
"Server" and "Email" in the report. Could you clarify why?
4. Following the previous point, since this Root CA does not issue TLS
certificates, it should not require a BR or EV Audit. Is this assumption
correct?
5. TWCA Global Root CA G2 has indeed cross-certified by TWCA Global Root
CA. The cross-certificate (D53BF4968A7DB3C8...) has "Audits Same as Parent"
checked,. Could you confirm?
6. We have noticed warnings regarding CRL expiration, but after verifying
the CRLs downloaded from the CDP, they all appear to be valid. Could you
confirm?
7. We observed that in the Subject CN field, only TWCA includes the word
"Root," while other CAs only list Intermediate CAs. Is this a coincidence, or
does TWCA need to make any adjustments?
If we have misunderstood the information presented on the disclosure page or
misinterpreted any CCADB attributes, please let us know. If this is confirmed
as an incident, we will disclose it on Bugzilla following the latest CCADB
incident reporting template.
Thank you.
Best regards,
ChyaHung Tsai
TWCA
Rob Stradling 在 2025年3月6日 星期四清晨5:03:38 [UTC+8] 的信中寫道：
Per the Mozilla, Apple, and Microsoft root program policies, all CA Owners with
one or more Root or Intermediate CAs trusted for the issuance of S/MIME
certificates should have completed an S/MIME BR audit by now and disclosed the
audit details on each applicable CCADB record.
I recently added tracking to
https://crt.sh/mozilla-disclosures<https://urldefense.com/v3/__https://crt.sh/mozilla-disclosures__;!!J5K_pWsD!yasWOllrX91fE5MB_c22RVmjkVN3I1l_ArKr0Mj1LSpP3ggyCjbi89Rf1bnsQM1ch-O2oM39ojqOiw$>
to flag missing and inconsistent disclosures of S/MIME BR audits. Since this
crt.sh report is currently flagging issues for a number of CA Owners, I thought
I would share a summary of the findings here. In my view, most (if not all) of
these issues should be treated as incidents per
https://www.ccadb.org/cas/incident-report<https://urldefense.com/v3/__https://www.ccadb.org/cas/incident-report__;!!J5K_pWsD!yasWOllrX91fE5MB_c22RVmjkVN3I1l_ArKr0Mj1LSpP3ggyCjbi89Rf1bnsQM1ch-O2oM3ofm3a4Q$>.
CA Owners with Missing S/MIME BR Audit details:
GoDaddy:
Several applicable Root Certificate records don’t specify any S/MIME BR audit
details. The WebTrust seals on
https://certs.godaddy.com/repository<https://urldefense.com/v3/__https://certs.godaddy.com/repository__;!!J5K_pWsD!yasWOllrX91fE5MB_c22RVmjkVN3I1l_ArKr0Mj1LSpP3ggyCjbi89Rf1bnsQM1ch-O2oM1YytVqvg$>
do not include an S/MIME BR seal. Has GoDaddy undergone an S/MIME BR audit?
TWCA:
No S/MIME BR audit details have been disclosed on one Root Certificate record.
This root CA isn’t directly trusted for S/MIME, but it counts as S/MIME-capable
because it’s cross-certified by a root that is trusted for S/MIME. Is ticking
“Audits Same as Parent” the required resolution here?
DigitalSign - Certificadora Digital, S.A.:
Two root certificates have only the Email trust bit set in NSS, but the
corresponding Root Certificate records in CCADB have no S/MIME BR audit details
disclosed. Has DigitalSign undergone an S/MIME BR audit?
eMudhra:
Two applicable Intermediate Certificate records don’t specify any S/MIME BR
audit details. Is ticking “Audits Same as Parent” the required resolution here?
Entrust:
Two applicable Root Certificate records don’t specify any S/MIME BR audit
details. Although these roots have been distrusted for further issuance of TLS
server certificates, they are still fully trusted for the issuance of S/MIME
certificates. Has Entrust undergone an S/MIME BR audit?
Siemens (externally-operated Sub-CAs under Entrust):
Several applicable Intermediate Certificate records specify no S/MIME BR audit
details. Has Siemens undergone an S/MIME BR audit?
Ministerie van Defensie (externally-operated Sub-CA under PKIoverheid):
One applicable Intermediate Certificate record doesn’t specify any S/MIME BR
audit details. See also
https://bugzilla.mozilla.org/show_bug.cgi?id=1911335<https://urldefense.com/v3/__https://bugzilla.mozilla.org/show_bug.cgi?id=1911335__;!!J5K_pWsD!yasWOllrX91fE5MB_c22RVmjkVN3I1l_ArKr0Mj1LSpP3ggyCjbi89Rf1bnsQM1ch-O2oM026d-DxA$>.
LAWtrust:
One applicable Root Certificate record doesn’t specify any S/MIME BR audit
details. Has LAWtrust undergone an S/MIME BR audit?
Cybertrust Japan (externally-operated Sub-CA under SECOM Trust Systems):
One applicable Intermediate Certificate record doesn’t specify any S/MIME BR
audit details. See also
https://bugzilla.mozilla.org/show_bug.cgi?id=1950574<https://urldefense.com/v3/__https://bugzilla.mozilla.org/show_bug.cgi?id=1950574__;!!J5K_pWsD!yasWOllrX91fE5MB_c22RVmjkVN3I1l_ArKr0Mj1LSpP3ggyCjbi89Rf1bnsQM1ch-O2oM1CjFi7NA$>.
CA Owners with Inconsistent Disclosure of S/MIME BR Audit details:
Asseco Data Systems:
One applicable Root Certificate record doesn’t specify any S/MIME BR audit
details. Although this root certificate is not present in root stores, its
signature can be validated by a doppelganger root that is. (The serial number
of this self-signed root certificate appears in the CRL, but I think it’s
questionable as to whether self-signed certificates can actually be revoked in
this manner. This self-signed root certificate is also listed in OneCRL, but
AIUI OneCRL is only applicable to Firefox’s use of TLS server certificate
chains, meaning that it’s out of scope for Mozilla’s interest in S/MIME).
DigiCert:
Two applicable Root Certificate records don’t specify any S/MIME BR audit
details. These root CAs aren’t directly trusted for S/MIME, but they do
inherit S/MIME-capability via cross-certification from other DigiCert roots.
(The CCADB records for the cross-certificates all specify “Audits Same as
Parent”, and the corresponding parent records do specify S/MIME BR audit
details).
Microsec:
Similar to the Asseco Data Systems case, a doppelganger Root Certificate record
doesn’t specify any S/MIME BR audit details.
Cybertrust Japan (externally-operated Sub-CA under SECOM Trust Systems):
One applicable Intermediate Certificate record doesn’t specify any S/MIME BR
audit details (see above), whereas a doppelganger Intermediate Certificate
record does. See also
https://bugzilla.mozilla.org/show_bug.cgi?id=1950574<https://urldefense.com/v3/__https://bugzilla.mozilla.org/show_bug.cgi?id=1950574__;!!J5K_pWsD!yasWOllrX91fE5MB_c22RVmjkVN3I1l_ArKr0Mj1LSpP3ggyCjbi89Rf1bnsQM1ch-O2oM1CjFi7NA$>.
Telia:
In two cases, the S/MIME BR audit Statement Date differs between a Root
Certificate record and a corresponding Intermediate Certificate
(cross-certificate) record.
apple-disclosures
I have also added tracking to
https://crt.sh/apple-disclosures<https://urldefense.com/v3/__https://crt.sh/apple-disclosures__;!!J5K_pWsD!yasWOllrX91fE5MB_c22RVmjkVN3I1l_ArKr0Mj1LSpP3ggyCjbi89Rf1bnsQM1ch-O2oM2MBBqsOQ$>
to flag missing and inconsistent disclosures of S/MIME BR audits. This report
currently flags issues for some additional CA Owners, but since crt.sh is not
yet tracking all of the intricacies of Apple’s root store metadata there may be
some false positives.
--
Rob Stradling
Distinguished Engineer
Sectigo Limited
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