Microsoft PKI Services: CA Certificates not published in DER Encoded Format

Microsoft PKI Services identified that eight certificates published to the AIA repository were incorrectly encoded in PEM format instead of the required DER format, violating RFC 5280 Section 4.2.2.1. This issue was self-identified and did not halt certificate issuance, as the certificates themselves were not malformed. The team initiated a staged deployment to replace the affected certificates and update their publishing process to prevent future occurrences. All action items related to this incident have been completed.

1. 2023-06-27 Microsoft PKI Services published 8 CA certificates to the AIA file repository.
2. 2024-03-20 Completed replacement of 8 old PEM encoded files with new DER encoded files.
3. 2024-03-26 Updated AIA publishing process to check for DER encoding.
4. 2024-04-01 All repair items related to the incident were completed.