(CBS DETROIT) – Michigan Medicine alerted about 57,891 patients that their health information was possibly exposed in a data breach, marking the health system’s second cyberattack this year. 

This breach occurred after an employee’s email account was compromised, according to a release.

“A Michigan Medicine employee accepted an unsolicited multifactor authentication prompt, which allowed the cyberattacker to access the employee’s email account and its contents,” Michigan Medicine said in a release. “The event occurred on July 30, 2024. The account was disabled as soon as possible so no further access could take place.”

Some emails and attachments contained patient information, including names, medical record numbers, diagnostics and treatment information. 

“The emails were job-related communications for treatment and coordination for Michigan Medicine patients,” according to the release. “The information involved for each specific patient varied, depending on the particular email or attachment.   

While investigating, Michigan Medicine didn’t find evidence to believe that this attack aimed to gain access to health information.

Still, data theft couldn’t be ruled out, and all emails involved were considered compromised and reviewed. The review happened from Aug. 21 to Aug. 29.

When they discovered the breach, Michigan Medicine blocked the cyberattacker’s IP address was blocked, and password changes were made. 

Michigan Medicine says the emails did not include Social Security Numbers, bank account numbers, or credit or debit card information. 

“Additionally, Michigan Medicine is taking swift action to ward off future cyberattacks that target employees including decreasing time emails are retained, modifying our identity verification processes to access Michigan Medicine systems, and increased education on the use of the multifactor identification,” Michigan Medicine said. 

The employee believed in the breach has also been “subject to disciplinary action under Michigan Medicine policies and procedures.”

“Patient privacy is of the utmost importance,” said Michigan Medicine. “At Michigan Medicine, we continue to be vigilant as cyberattacks become more and more sophisticated. We will analyze this incident and review our safeguards and make changes if needed to protect those we care for.” 

On Sept. 26, Michigan Medicine started mailing notices to the impacted patients. People who are concerned and do not receive a letter can contact the toll-free Michigan Medicine Assistance Line: 1-877-225-2078 with questions from 9 a.m. to 9 p.m. Monday through Friday. 

Michigan Medicine patients were also impacted by a data breach in May.