“Kootenai Health discovered that the attackers had access to its network for over a week, and that certain data was exfiltrated on February 22.”
The data left on February 22. Kootenai noticed on March 2 and mailed letters to 464,088 people on August 12. The haul covers Social Security numbers, diagnoses, medications and insurance details, and 3AM has already published a 22 GB archive. Victims get 12 months of credit monitoring for data that stays stolen forever.