[cabfpub] Use of wildcard certificates by cloud operators

Rich Smith richard.smith at comodo.com
Tue May 6 13:16:27 MST 2014

> -----Original Message-----
> From: Kelvin Yiu [mailto:kelviny at exchange.microsoft.com]
> Sent: Tuesday, May 06, 2014 3:58 PM
> There is also a question about whether these wildcard rules should be
> applied equally to DV and OV certificates. Both Microsoft and Google
> (AFAIK) issue OV certificates from their own CA to their own cloud
> operations, so I am interested in hearing what the forum thinks.
[RWS] IMO, the same rules should apply to DV and OV.  A couple reasons for that:
1) As a practical matter it is nearly impossible for a CA to police such a differentiation and trying to do so would be pretty arbitrary
2) The browsers do not at this time offer any differentiation between DV and OV, and many have pushed the interface for the user to view the actual certificate details deeper and deeper into the UI making it even more difficult for users to differentiate for themselves, so I don't see much point in us trying to differentiate usage rules unless the browsers want to change their stance on DV vs. OV in the UI.

> Kelvin
> -----Original Message-----
> From: Rich Smith [mailto:richard.smith at comodo.com]
> Sent: Tuesday, May 6, 2014 11:11 AM
> To: ben at digicert.com; 'Gervase Markham'; Kelvin Yiu; sleevi at google.com;
> public at cabforum.org
> Subject: RE: [cabfpub] Use of wildcard certificates by cloud operators
> I agree with the approach of giving the cloud operator the opportunity
> to remedy the situation.  Assuming the key has not been compromised,
> what we are looking for here is the end of the particular threat.  The
> best solution for all concerned is that the offending content is
> removed as quickly as possible, and with minimal interference to the
> cloud operator, and the honest members of their customer base.  If the
> cloud operator is unresponsive, or seems to continuously have these
> types of problems out of proportion to other operators, then we can use
> revocation.
> Something that needs to be pointed out here is that browser revocation
> checking/handling is spotty and there's nothing this Forum can do about
> that.  Some browsers, members of this Forum, have made perfect the
> enemy of good with respect to revocation handling and in so doing have
> completely dropped the ball for their users.  That being the case, to
> ALWAYS require revocation in this kind of instance without trying first
> to allow the cloud operator to handle the situation would still leave a
> lot of end users exposed.  What happens when we revoke, and those
> browsers who have chosen to punt on revocation checking don't pick it
> up because they've chosen performance over security, and the malicious
> content remains on the site?
> -Rich
> > -----Original Message-----
> > From: public-bounces at cabforum.org [mailto:public-
> bounces at cabforum.org]
> > On Behalf Of Ben Wilson
> > Sent: Tuesday, May 06, 2014 11:17 AM
> > To: 'Gervase Markham'; 'Kelvin Yiu'; sleevi at google.com;
> > public at cabforum.org
> > Subject: Re: [cabfpub] Use of wildcard certificates by cloud
> operators
> >
> > If the Baseline Requirements don't quite address the problem (higher
> > risk) the way we would like them to, then we ought to draft and
> > propose an amendment that says what we want it to say.  For instance,
> > on #2 below, do we allow the cloud operator the opportunity to remedy
> > the problem and only revoke certificates where the operator fails to
> > take action with a certain amount of time?  Would an escalation
> > procedure or ratcheting process be good to include in the
> > pre-revocation stage?  Are there procedures elsewhere that have
> worked
> > well in these types of relationships that could be adapted to this
> use case?
> >
> >
> > -----Original Message-----
> > From: public-bounces at cabforum.org [mailto:public-
> bounces at cabforum.org]
> > On Behalf Of Gervase Markham
> > Sent: Tuesday, May 06, 2014 4:01 AM
> > To: Kelvin Yiu; public at cabforum.org
> > Subject: Re: [cabfpub] Use of wildcard certificates by cloud
> operators
> >
> > I agree with Ryan :-)
> >
> > On 05/05/14 18:10, Kelvin Yiu wrote:
> > > 1.       Section 11.1.3 of the BR explicitly disallow wildcard
> > > certificates for registry controlled domains (e.g. *.com). The
> > Mozilla
> > > maintained http://publicsuffix.org is cited as an example of a
> > > public suffix list where Azure, GAE, and AWS domains can be found.
> > > Does the current usage of wildcard certificates by cloud operators
> > > violate the BR? If so, is this intentional and what is the reason?
> >
> > No. The PSL is in two sections for precisely this reason - there are
> > privately-owned sites where an e.g. appspot.com cookie should not be
> > allowed (allows one appspot site to perform cookie fixation attacks
> > against another) but a *.appspot.com cert should be allowed. So we
> > split the PSL logically into two to put sites like this in their own
> > section.
> >
> > > 2.       Section 13.1.5 of the BR explicitly require wildcard
> > > certificates that were “used to authenticate fraudulently
> misleading
> > > subordinate FQDN” to be revoked within 24 hours. If the fraudulent
> > > sites never had access to the private key of the wildcard
> > > certificate and the cloud operator has a process to take down
> > > fraudulent sites, should these wildcard certificates be required to
> be revoked?
> >
> > Hmm. This is tricky. I suspect this situation was not considered when
> > we wrote that. I'd lean towards No, but I'm not sure that's what the
> > BRs say on their face, and I'd welcome more discussion.
> >
> > Gerv
> > _______________________________________________
> > Public mailing list
> > Public at cabforum.org
> > https://cabforum.org/mailman/listinfo/public
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