Dear all, This email is the formal reply from WoSign for this 3 incidents.
First, thank you all very much to help WoSign to improve our system security that helped the global Internet security. And I am very sorry deeply for the related 33 misissuance certificates subscribers that we like to offer a free EV SSL certificates upgrade as compensation after finishing the EV validation. Second, we are very sorry to all browsers that we don't notify you after the incident, this is a mis-understanding problem of the bug report policy. And we never do this way again in the future. Now we are very clear that all misissuance case and other security incident must revoke the certificate instantly and report to all browsers and related parties. We guarantee we will do this well in the future. Third, due to the English language limit, we know we can't understand all related international standard that it may have some bugs in the system in the past and maybe in the future, so we have logged all issued SSL certificates to CT Log servers since July 5th, this is for full transparency, and for easy and quickly find out any problems. All browsers can distrust the SSL certificate issued by WoSign after July 5th that no SCT data embedded in the certificate. And we even plan to log all code signing certificate and all client certificate to CT log server for full transparency completely in the future. For current case, as promised in this email thread, we will post all issued SSL certificate in 2015 to CT log server soon. For incident 0: We start to use the higher port website control validation from Jan. 8th, 2015 since some customer can't use the 80 and 443 port. And we have closed this function after getting report from Google at April 24, 2015. We checked our system, the certificates issued related using higher level port website control validation is totally 72 certificates. To be clear, those certificates are validated by website control validation method that using other port except 80 and 443. So we think no need to revoke those certificates. We posted all those certificates to CT log server for transparency and provided the crt.sh link in this email thread. For incident 1: We checked our system that the mis-issued certificate with un-validated subdomain, total 33 certificates. We have posted to CT log server and provided the crt.sh link in this email thread. All certificates are revoked today after noticing each subscriber. This is a system bug for the rule of adding additional domains to SAN for free, the rule is if you validated the domain: wosign.com, and you apply certificate for wosogn.com, then system will add a domain www.wosign.com in SAN for free, this is for the subscriber convenience that no any problem if the site visitor visit https://wosign.com and https://www.wosign.com. This is no any problem in domain control validation, but for website control validation method, it will have problem, the code engineer mis-understand this free add-domain policy, this is a code bug that we don't find even we revoked some misissuance certificate, this bug is fixed completely at Aug. 9th, 2015 system update. We classified this 33 misissuance certificate into two types: one type is we think this misissuance certificate is obviously not from the domain owner, we revoked this type certificates instantly after we know the misissuance; another type is, this certificate is a normal order that the subscriber own this domain, it is our system bug fault to add a wrong sub-domain to the certificate, in order to not interrupt those subscriber's website normal operation, we must notice those subscriber first, reissue a correct one for this subscriber, then revoke this certificate. Considering the website control validation method has potential risk, we have closed this method at Aug. 27 even the BR allow this method. There are many famous Internet service providers provide subdomain to its customer, we can't add all of their domains to our Flag-Block system. So we decided to close this validation method, only support domain control validation. For incident 2: We declared this big in Bugzilla [4], this is not the case that we want to issue backdated SAH1 certificate, this is a bug that used by the test company to issued two certificates only. StartCom and WoSign used the same auto-generation script, set different parameter to go to different CA API URL. Now StartCom and WoSign all decided to use Let Encrypted ACME protocol that it will support this case -- one same client software can be used to get certificate from different CA, just define the CA parameter. We revoked this two wrong SHA1 certificate instantly after getting report. And we disabled this bug in API, and StartCom stopped StartEncrypt service. I wish I say this 3 case clearly, if not, please forgive my bad English, and please contact me if you still have any question, thanks a million. Best Regards, Richard Wang CEO WoSign CA Limited -----Original Message----- From: Gervase Markham [mailto:g...@mozilla.org] Sent: Wednesday, August 24, 2016 9:08 PM To: mozilla-dev-security-pol...@lists.mozilla.org Cc: Richard Wang <rich...@wosign.com> Subject: Incidents involving the CA WoSign Dear m.d.s.policy, Several incidents have come to our attention involving the CA "WoSign". Mozilla is considering what action it should take in response to these incidents. This email sets out our understanding of the situation. Before we begin, we note that Section 1 of the Mozilla CA Certificate Enforcement Policy[0] says: "When a serious security concern is noticed, such as a major root compromise, it should be treated as a security-sensitive bug, and the Mozilla Policy for Handling Security Bugs should be followed." It is clear to us, and appears to be clear to other CAs based on their actions, that misissuances where domain control checks have failed fall into the category of "serious security concern". Incident 0 ---------- On or around April 23rd, 2015, WoSign's certificate issuance system for their free certificates allowed the applicant to choose any port for validation. Once validation had been completed, WoSign would issue certificates for that domain. A researcher was able to obtain a certificate for a university by opening a high-numbered port (>50,000) and getting WoSign to use that port for validation of control. This problem was reported to Google, and thence to WoSign and resolved. Mozilla only became aware of it recently. * Before the recent passage of Ballot 169 in the CAB Forum, which limits the ports and paths which can be used, the Baseline Requirements said that one acceptable method of domain validation was "Having the Applicant demonstrate practical control over the FQDN by making an agreed‐upon change to information found on an online Web page identified by a uniform resource identifier containing the FQDN". This method therefore did not violate the letter of the BRs. However, Mozilla considers the basic security knowledge that ports over 1024 are unprivileged should have led all CAs not to accept validations of domain control on such ports, even when not documented in the BRs. * The misissuance incident was not reported to Mozilla by WoSign as it should have been (see above). * This misissuance incident did not turn up on WoSign's subsequent BR audit[1]. Incident 1 ---------- In June 2015, an applicant found a problem with WoSign's free certificate service, which allowed them to get a certificate for the base domain if they were able to prove control of a subdomain. The reporter proved the problem in two ways. They accidentally discovered it when trying to get a certificate for med.ucf.edu and mistakenly also applied for www.ucf.edu, which was approved. They then confirmed the problem by using their control of theiraccount.github.com/theiraccount.github.io to get a cert for github.com, github.io, and www.github.io. They reported this to WoSign, giving only the Github certificate as an example. That cert was revoked and the vulnerability was fixed. However recently, they got in touch with Google to note that the ucf.edu cert still had not been revoked almost a year later. * The lack of revocation of the ucf.edu certificate (still unrevoked at time of writing, although it may have been by time of posting) strongly suggests that WoSign either did not or could not search their issuance databases for other occurrences of the same problem. Mozilla considers such a search a basic part of the response to disclosure of a vulnerability which causes misissuance, and expects CAs to keep records detailed enough to make it possible. * This misissuance incident was not reported to Mozilla by WoSign as it should have been (see above). * This misissuance incident did not turn up on WoSign's subsequent BR audit[1]. Incident 2 ---------- In July 2016, it became clear that there was some problems with the StartEncrypt automatic issuance service recently deployed by the CA StartCom. As well as other problems it had, which are outside the scope of this discussion, changing a simple API parameter in the POST request on the submission page changed the root certificate to which the resulting certificate chained up. The value "2" made a certificate signed by "StartCom Class 1 DV Server CA", "1" selected "WoSign CA Free SSL Certificate G2" and "0" selected "CA 沃通根证书", another root certificate owned by WoSign and trusted by Firefox. Using the value "1" led to a certificate which had a notBefore date (usage start date) of 20th December 2015, and which was signed using the SHA-1 checksum algorithm. * The issuance of certificates using SHA-1 has been banned by the Baseline Requirements since January 1st, 2016. Browsers, including Firefox, planned to enforce this[2] by not trusting certs with a notBefore date after that date, but in the case of Firefox the fix had to be backed out due to web compatibility issues. However, we are considering how/when to reintroduce it, and CAs presumably know this. * The issuance of backdated certificates is not forbidden, but is listed in Mozilla's list of Problematic Practices[3]. It says "Minor tweaking for technical compatibility reasons is accepted, but backdating certificates in order to avoid some deadline or code-enforced restriction is not." * WoSign deny that their code backdated the certificates in order to avoid browser-based restrictions - they say "this date is the day we stop to use this code"[4]. If that is true, it is not clear to us how StartCom came to deploy WoSign code that WoSign itself had abandoned. * It seems clear from publicly available information that StartCom's issuance systems are linked to WoSign's issuance systems in some way. Nevertheless, it should not have been possible for an application for a cert from StartCom to produce a cert signed by WoSign. * This misissuance incident was not reported to Mozilla by WoSign as it should have been. Taking into account all these incidents and the actions of this CA, Mozilla is considering what action to take. Your input is welcomed. Gerv, Kathleen and Richard [0] https://www.mozilla.org/en-US/about/governance/policies/security-group/certs/policy/enforcement/ [1] https://cert.webtrust.org/SealFile?seal=2019&file=pdf [2] https://bugzilla.mozilla.org/show_bug.cgi?id=942515 [3] https://wiki.mozilla.org/CA:Problematic_Practices#Backdating_the_notBefore_date [4] https://bugzilla.mozilla.org/show_bug.cgi?id=1293366 _______________________________________________ dev-security-policy mailing list dev-security-policy@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-security-policy
