The ransomware incident was reported by healthcare giant Ascension on 8 May.
A spokesperson for the company said: 'On Wednesday, May 8, we detected unusual activity on select technology network systems, which we now believe is due to a cybersecurity event. At this time we continue to investigate the situation. We responded immediately, initiated our investigation and activated our remediation efforts. Access to some systems have been interrupted as this process continues.'
The cyber attack impacted electronic health records systems, phone systems and others systems used to order tests, procedures and medications.
In an update on 11 May, Ascension said: 'We continue to diligently investigate and address the recent ransomware incident, working closely with industry leading cybersecurity experts to assist in our investigation and restoration and recovery efforts. Additionally, we have notified law enforcement, as well as government partners including the FBI, the Cybersecurity and Infrastructure Security Agency, the Department of Health and Human Services, and the American Hospital Association. We remain in close contact with the FBI and CISA, and we are sharing relevant threat intelligence with the Health Information Sharing and Analysis Center so that our industry partners and peers can take steps to protect themselves from similar incidents.
'While our restoration work continues in earnest, our focus is on restoring systems as safely as possible. While we expect this process will take time to complete, we are making progress and systems are being restored in a coordinated manner at each of our care sites. We will continue to share updates on our recovery process.'