Grand Blanc, Mich.-based McLaren Health Care said it has experienced a ransomware attack shortly after a ransomware gang took credit for it, The Record reported Sept. 29.
"Based on our investigation, we have determined that we experienced a ransomware event. We are investigating reports that some of our data may be available on the dark web and will notify individuals whose information was impacted, if any, as soon as possible," a spokesperson for the health system told the publication.
The Black Cat/AlphV reportedly posted on its leak site that it was behind the Sept. 5 attack on McLaren's computer systems that affected its billing and EHR at 14 hospitals.
The group is claiming to have stolen 6 TB of data, including the personal data of millions as well as videos of McLaren's work.
The health system said its systems remain operational and that it is working with global cybersecurity specialists to assist in its investigation.
McLaren has also taken measures to further strengthen its cybersecurity posture since the event, it said.