In recent weeks, a number of CAs have filed incident reports relating to 
mistakes made when setting critical flags in Subscriber certificate extensions 
since the TLSBRv2 profiles came into force.  We thought it would be worth 
performing a comprehensive survey ourselves in order to discover if any similar 
incidents at other CAs had not yet been detected.

I've run [1] against the primary crt.sh DB, which caused it to trawl through 
the crt.sh ID space starting around the time TLSBRv2 went into force to 
identify any Subscriber certificate containing any common extension with its 
critical flag set incorrectly per §7.1.2.7.6.  I've posted a report of the 
results at [2], which was generated using [3].

Seven further incidents were identified.  I sent Certificate Problem Reports to 
the two CAs whose affected PKI hierarchies are trusted by root programs whose 
representatives are active in monitoring Bugzilla.  Both of those CAs responded 
promptly and filed incident reports: [4] and [5].

Having gathered this data, today I've used it to cross-check the lists of 
affected certificates that CAs have provided with their incident reports.  I 
was surprised to find two bugs ([6] and [7]) without any attached list of 
affected certificates.  I also observed some patterns of "omissions" in the 
disclosed lists of affected certificates, for which I would like to call upon 
the root program owners to clarify their expectations; noting that the CCADB 
incident reporting requirements [8] say that each incident report's "Appendix 
must include a listing of the complete certificate details of all affected 
certificates":

  1.
Is a CA's incident report expected to disclose the affected certificates that 
have already expired prior to the CA's response to the incident?
  2.
Is a CA's incident report expected to disclose the affected certificates that 
have already been revoked prior to the CA's response to the incident?
  3.
Is a CA's incident report expected to disclose both an affected precertificate 
and its corresponding certificate?  Or just one of the pair?


[1] 
https://gist.github.com/robstradling/6a5ecca872cf28232d90638fc2c44ed5#file-check_extension_criticality-go
[2] 
https://gist.github.com/robstradling/6a5ecca872cf28232d90638fc2c44ed5#file-report-csv
[3] 
https://gist.github.com/robstradling/6a5ecca872cf28232d90638fc2c44ed5#file-generate_report-sh
[4] https://bugzilla.mozilla.org/show_bug.cgi?id=1888060
[5] https://bugzilla.mozilla.org/show_bug.cgi?id=1888104
[6] https://bugzilla.mozilla.org/show_bug.cgi?id=1887096
[7] https://bugzilla.mozilla.org/show_bug.cgi?id=1883416
[8] https://www.ccadb.org/cas/incident-report

--
Rob Stradling
Senior Research & Development Scientist
Sectigo Limited

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