[cabfpub] EV Wildcards

kirk_hall at trendmicro.com kirk_hall at trendmicro.com
Thu Mar 26 01:04:40 UTC 2015

All the arguments on the question of allowing EV Wildcard certs are well considered and valid on both sides.  Chris Bailey and I come down on the side of "no EV wildcard certs" for the following reason.

It's true that *.example.com could "hide" the use for facebook.example.com.  It's also true that the owner of example.com today could ask for an EV cert for facebook.example.com, and if the cert is issued, it's "no different" from using a wildcard cert *.example.com.

However, there is one important difference.  BR 11.5 (High Risk Requests) and the related EV Guideline 11.12.1 require the following:

BR 11.5 High Risk Requests
The CA SHALL develop, maintain, and implement documented procedures that identify and require additional verification activity for High Risk Certificate Requests prior to the Certificate's approval, as reasonably necessary to ensure that such requests are properly verified under these Requirements.

High Risk Certificate Request: A Request that the CA flags for additional scrutiny by reference to internal criteria and databases maintained by the CA, which may include names at higher risk for phishing or other fraudulent usage, names contained in previously rejected certificate requests or revoked Certificates, names listed on the Miller Smiles phishing list or the Google Safe Browsing list, or names that the CA identifies using its own risk-mitigation criteria.

Among other things, we interpret that to require CAs to scan FQDNs for "names at higher risk for phishing or other fraudulent usage" at every level in the FQDN, and as a matter of policy, we generally won't issue a cert for facebook.example.com unless the customer can show us it has Facebook's permission.  The same is true for a long list of other high risk names, and we apply the scan to all FQDNs in the SANs field as well.

So this means that under our policy and interpretation a customer could not get an EV cert from us for [high risk name].example.com, which helps cut down on the likelihood of fraud or imitation.  An EV cert for *.example.com, on the other hand, could be used to secure the same high risk name FQDN.

We recognize that other CAs may not have a policy as restrictive as ours for EV certs, but if another CA issues an EV cert for facebook.example.com and it's used for fraud or phishing - presumably that CA will get very adverse publicity, and will have some explaining to do to the public.  That is likely to keep the number of such high risk name EV certs to a minimum.  In contrast, no scanning or review will happen for EV wildcard certs.

So in that sense, there is a difference, and we think wildcard certs should not be issued for EV - prohibiting EV wildcard certs makes CAs a bit more responsible, in our opinion.

Kirk R. Hall
Operations Director, Trust Services
Trend Micro

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