MediSecure Data Breach: 12.9 Million Australian Users’ Sensitive Data Hacked

**Executive summary:** MediSecure, a former Australian electronic prescription provider, disclosed a large-scale incident in which a database server was encrypted (likely by ransomware) and roughly 6.5 TB of sensitive personal and medical data belonging to about 12.9 million Australians was stolen; the breach led to the company's administration, involvement of national cyber and law enforcement authorities, and reassignment of ePrescription services by the government.