HARICA: Insufficient serial number entropy

This case concerns HARICA’s discovery and disclosure of a compliance issue with certificate serial number entropy. HARICA reported that Mozilla-dev-security-policy discussion revealed that EJBCA’s default serial number configuration effectively produced serial numbers with 63 truly random bits because the serial number must be positive, making the first bit zero. HARICA stated it monitored the discussion and determined its EJBCA configuration was using the default serial number size, leading to issuance of non-compliant serial numbers between 2018-05-04 and 2019-03-05. HARICA conducted a full certificate database scan and reported 461 SSL/TLS, 4157 S/MIME, and 15 CA certificates (unexpired and unrevoked) with improper serial numbers, plus additional affected certificates issued from a CA with improper serial numbers. HARICA planned revocations for the problematic SSL/TLS certificates by March 16, 2019 and for CA certificates capable of issuing SSL/TLS certificates by March 18, 2019, and later reported that all scheduled revocations were performed as planned. The bug was resolved as FIXED, and a participant noted that remediation appeared complete.

1. 2018-05-04 HARICA began issuing certificates with non-compliant serial number entropy after migrating to EJBCA.
2. 2019-03-05 The period of issuance with non-compliant serial number entropy ended.
3. 2019-03-15 HARICA disclosed the incident to Mozilla and provided an incident report describing the affected certificates and planned revocations.
4. 2019-03-16 Planned revocation date for problematic SSL/TLS certificates.
5. 2019-03-18 Planned revocation date for CA certificates capable of issuing SSL/TLS certificates.
6. 2019-03-19 HARICA submitted a final incident report stating scheduled revocations were performed as planned.

1. 2019-03-15 HARICA — HARICA described the incident, explaining how EJBCA’s default serial number configuration resulted in effectively 63 bits of entropy and listing the affected certificate counts and planned revocation timelines.
2. 2019-03-15 HARICA — HARICA corrected the incident report executive summary regarding the serial number bits used in its earlier custom CA software.
3. 2019-03-19 HARICA — HARICA stated that all scheduled revocations were performed as planned and that the final report includes this information.
4. 2019-03-29 Fastly representative — A participant commented that remediation appeared complete.