A new ransomware attack is currently rocking computers in in more than 70 countries around the world, but the vast majority of Windows users should be protected. A Microsoft spokesperson speaking to Sky News has confirmed that customers who have Windows Updates enabled and are running "free antivirus software" (e.g. Windows Defender) should be protected.

That's good news for Windows users who are current with their updates. But the ransomware, known as "WannaCry," has already been seen rapidly spreading through organizations in more than 70 countries, the BBC reports. Notably, the National Health Service (NHS) in the UK has been impacted, along with Telefonica in Spain, and many others.

The attack, which the BBC reports is locking down computers and demanding a ransom of $300 (£230) in Bitcoin, is reportedly related to National Security Agency (NSA) hacking tools that were leaked by a group known as The Shadow Brokers earlier this year. The particular vulnerability exploited by the hack was previously patched by Microsoft in March, but it seems businesses and other organizations affected by today's attack haven't yet installed the patch.