A worldwide ransomware attack has infected more than 200,000 computers in more than 150 countries since Friday. One of its most prominent targets was the U.K. National Health Service, which is still facing disruption from the Friday attack, BBC reports.
Here are four things to know.
1. The ransomware attack hit 47 English NHS facilities, 16 of which are still facing service disruptions. England's largest trust, Barts Health NHS Trust, told BBC it had to cancel some surgical and outpatient services Monday and Tuesday as a result of the disruptions.
2. The majority of affected hospitals — including Barts Health NHS Trust — reopened their facilities for emergency care and are no longer diverting ambulances, as they were Friday. Two NHS facilities are still diverting emergency care patients as of Monday, down from seven on Sunday.
3. Dr. Anne Rainsberry, national incident director at NHS England, told BBC hospital services are improving. "The message to patients is clear: the NHS is open for business. Staff are working hard to ensure that the small number of organizations still affected return to normal shortly," she said.
4. Security experts report the ransomware variant exploits a vulnerability discovered by the U.S. National Security Agency, according to news outlets like The New York Times. Many organizations, including hospitals, reportedly did not updated their systems to address this vulnerability.
However, Health Secretary Jeremy Hunt told BBC NHS upgraded its security before Friday, developing a security center and reducing the use of computers on old operating systems. He also emphasized more than 80 percent of the NHS system was unaffected.