All,

It has been recommended that Mozilla replace its wiki page on delayed 
revocation incident reporting.  Here is a draft for your review and comment.

Ben

URL:  https://wiki.mozilla.org/CA/Responding_To_An_Incident#Revocation


Goals:  Mozilla’s goals are: to ensure that revocation occurs as swiftly as 
possible while maintaining the overall security and stability of the web; 
to reduce delayed revocation incidents to the greatest extent possible; to 
improve delayed revocation incident reports; and to gather better 
information on those cases where delayed revocation occurs. 

Date to Go Live:  January 17, 2025

Revocation

Mozilla’s Expectations on Revocation

CA operators MUST revoke misissued or otherwise problematic TLS server 
certificates within 24 hours or 5 days, depending on the circumstances set 
forth in section 4.9.1 
<https://cabforum.org/working-groups/server/baseline-requirements/requirements/#491-circumstances-for-revocation>
 
of the CA/Browser Forum’s TLS Baseline Requirements (TLS BRs).  Mozilla 
does not grant exceptions to the revocation requirements of the TLS BRs. 

To ensure compliance with the TLS BRs, Mozilla requires that CA operators:

   - 
   
   engage in proactive communication and advise subscribers well in advance 
   about the revocation timelines and explicitly warn them against using 
   publicly-trusted TLS server certificates on systems that cannot tolerate 
   timely revocation;
   - 
   
   include appropriate language in customer agreements requiring 
   subscribers’ timely cooperation in meeting revocation timelines and 
   acknowledging the CA’s obligations to adhere to applicable policies and 
   standards;
   - 
   
   prepare and maintain credible plans to address mass revocation events, 
   including detailed procedures for handling mass revocations effectively, 
   including rapid communication with affected parties and conducting annual 
   plan testing; and 
   - 
   
   engage a third party assessor to evaluate whether the CA Operator has: 
   - 
      
      credible plans to handle mass revocation events; 
      - 
      
      tested the operational effectiveness of the plans, including the 
      accuracy and adequacy of documentation of plan testing, including 
      timelines, results, and remediation steps; and 
      - 
      
      incorporated feedback from such exercises to improve future 
      readiness.  
      
Incident Reporting

The CCADB incident reporting process 
<https://www.ccadb.org/cas/incident-report> ensures the Web PKI community 
is informed and that issues are tracked and resolved effectively. Clear and 
timely communication fosters trust and accountability, mitigating risks to 
the ecosystem.

If a CA operator determines that it might delay revocation of certificates 
beyond the time period required by the TLS BRs, it MUST file a preliminary 
incident report with a Summary section immediately in Bugzilla, even if the 
delay has not yet occurred.

Such delayed revocation incident reports SHOULD be updated at least every 3 
days and MUST be updated no less frequently than every 7 days to describe a 
summary of:

   - 
   
   the number of certificates that have been revoked; 
   - 
   
   the number of certificates that have not yet been revoked;
   - 
   
   the number of certificates planned for revocation that have expired; and
   - 
   
   an estimate for when all remaining revocations will be completed. 
   
Consistent with CCADB incident reporting requirements, in the “Analysis” 
section, the CA operator SHALL explain in the Analysis section of the 
incident report those factors and rationales behind the decision to delay 
revocation (including detailed and substantiated explanations of how 
extensive harm would result to third parties–such as essential public 
services or widely relied-upon systems–and why the situation is 
exceptionally rare and unavoidable).

Also, the Timeline section should include the time(s) at which the CA 
Operator actually completed revocation of affected certificates, and the 
Action Items list MUST include steps reasonably calculated to prevent or 
reduce future revocation delays.

Consequences of Delayed Revocations

Failing to meet the standards of timely revocation erodes trust in the Web 
PKI and poses risks to global internet security.  Delayed revocation is a 
measure of last resort and MUST not be used routinely.  Repeated incidents 
of delayed revocation without sufficient justification will result in 
heightened scrutiny and sanctions, including removal of the CA from the 
Mozilla Root Store. CA operators must also adhere to the policies and 
revocation requirements of other Root Store Programs that include their CA 
certificates.  Additionally, all delayed revocation incidents MUST be 
listed as findings in the CA operator’s next TLS BR audit statement.



On Saturday, January 11, 2025 at 8:04:43 PM UTC-7 Matt Palmer wrote:

> On Fri, Jan 10, 2025 at 06:21:02PM -0800, Suchan Seo wrote:
> > Wouldn't fixed 30 certificates per CA cause smaller CA just spam load
> > genenrate test certificates on production envirement to delude chance to 
> it
> > actually hit acutal client?
>
> It is certainly a possibility. However, that sort of thing leaves
> extensive evidence (which, I will note, a CA-driven "random" choice
> protocol does not), and if such evidence was found and brought to light
> publicly, I expect it would not reflect well on the CA involved.
>
> Also, in the protocol I proposed, as Mozilla has full discretion over
> the the criteria by which certificates are chosen for a revocation test,
> it does not have to select those certificates entirely at random. It
> could identify certificates issued for the purposes you describe, and
> just not include such certificates in the list of those to be revoked.
>
> - Matt
>
>

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