Wildcard domains are already allowed. We can verify Wildcard DNS because a 
CNAME for *.domain.com is pointing to a record previously verified. This 
verification method is permitted under the definition of Authorization Domain 
Name (where the FQDN returned by a CNAME lookup can be used to verify the 
requested FQDN). Although <rnd>.domain.com isn’t necessarily distinguishable 
from *.domain.com, the validation ends up being the same because either its 
considered an Authorized Domain Name (under the definition) or it was validated 
as a random value in this new method. 

 

For example:

 

*.domain.com -> dcv.example.com (validated under the Authorized Domain Name 
section)

<rnd>.domain.com ->validation.example.com (validated under this new section)

 

Because each is validated properly, tracking which exact section was used in 
the validation isn’t necessary.

 

Jeremy

 

From: Ryan Sleevi [mailto:[email protected]] 
Sent: Friday, September 2, 2016 3:28 PM
To: Jeremy Rowley <[email protected]>
Cc: [email protected]
Subject: Re: [cabfpub] CNAME-based validation

 

Jeremy,

 

Does this introduce risk for sites that use Wildcard DNS records? How would you 
propose mitigating that risk?

 

On Fri, Sep 2, 2016 at 2:26 PM, Jeremy Rowley <[email protected] 
<mailto:[email protected]> > wrote:

I realized after reviewing my proposal that it will require a new method under 
the domain validation section. Therefore, I’m proposing we add the following as 
a new permitted method for domain validation:

 

Add the following as Section 3.2.2.4.11:

 

Confirming the Applicant’s control over the requested FQDN by appending a 
Random Value or Request Token as a sub domain to an Authorization Domain Name 
and pointing the CNAME record of the created sub domain to a FQDN verified by 
the CA using one of methods permitted under Section 3.2.2.4

 

Looking for two endorsers.

 

Jeremy


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