Ascension: employee mistake allowed ransomware attackers access

One of the largest health systems in the country says it's figured out how ransomware attackers were able to massively disrupt some 140 hospitals across the U.S.

Ascension was hit with a cyber attack on May 8 that caused major delays in lab and test results, and made electronic health records unavailable for weeks. Doctors and nurses inside Ascension hospitals in Michigan say it's caused chaotic, dangerous conditions that have led to medication errors and possibly harm to patients.

On Wednesday, Ascension posted an update on its website saying an “individual working in one of our facilities accidentally downloaded a malicious file that they thought was legitimate. We have no reason to believe this was anything but an honest mistake.”

The attackers were able to take files from seven of the approximately 25,000 servers across its network, according to Ascension. And some of those files may "contain Protected Health Information and Personally Identifiable Information," though Ascension didn’t say how many people may have been affected.

“Right now, we don’t know precisely what data was potentially affected and for which patients," the company said in a statement posted to its website Wednesday. "In the meantime, to provide our patients and associates with the greatest peace of mind possible, we are offering complimentary credit monitoring and identity theft protection services to any Ascension patient or associate who requests it, free of charge, and regardless of whether we determine in the future that their data was actually involved in this incident."

Ascension said people who want to enroll in free credit monitoring and identity theft protection services should call 1-888-498-8066.

The health care system said it's already restored electronic health record access in some of its Michigan hospitals, and hopes to have fully restored them across all hospitals by Friday.