A Microsoft store in New York. (Mark Lennihan/AP)

Are you one of those people who ignores prompts to update your Windows system? Well, Friday's massive international cyberattack may give you the best reason of all to hit “update” when prompted.

Microsoft on Friday said in a statement that it has "added detection and protection" to shield Windows users against WannaCrypt — the malicious software used to attack Britain's National Health Service, FedEx and other organizations. The company also said that users who downloaded a March security update should be shielded with "additional protection against this potential attack."

That lends credence to reports that suggest that the vulnerability exploited by the worm responsible for the attack is the same one revealed in April by the hacker group known as the Shadow Brokers. The Shadow Brokers alleged that the National Security Agency had used weaknesses in Windows as part of its digital surveillance efforts.

A massive cyberattack hit tens of thousands of computers in dozens of nations. Reports of the attack first surfaced in Britain, where the National Health Service described serious problems. (Sarah Parnass/The Washington Post)

Microsoft released a patch to fix those vulnerabilities on or before March 14.

Regular or auto updaters should have been covered by that patch. But if you haven't updated your system since then, do it now, regardless of whether you're a business or consumer.

Microsoft said in April that the problems had been fixed for anyone running Windows 7 or a newer system. According to the analytics firm NetMarketShare, about 7 percent of the world is still vulnerable to the malicious software. Those running versions of Exchange older than Exchange 2010 also are not protected.

“Customers still running prior versions of these products are encouraged to upgrade to a supported offering,” Microsoft said in April. For instructions on how to do that for your particular computer, visit Microsoft's help center.

"Those who are running our free antivirus software or have Windows Update enabled, are protected. We are working with customers to provide additional assistance," Microsoft said in statement.