More than 70 national have fallen victim to a global cyber-extortion attack called “Wannacry”.

Thousands of users, businesses, and government agencies have been hit by the ransomware which took advantage of a security hole in Microsoft Windows.

The hackers used leaked tools from the National Security Agency to exploit the hole. The malware spread through computers that weren’t updated.

Security experts say no one is immune to a ransomware attack, but the people who should be most concerned is anyone who hasn’t updated Windows.

People around the world reported their files encrypted and unreadable and received messages to pay hundreds of dollars, or their data would be destroyed.

Experts say users should make sure their computers have the latest security updates.

Troy Wilkinson, the CEO of Axiom Cyber Solutions, says this type of attack isn’t new, but it’s the wide-reaching scale that’s surprising.

“This is an internet worm that identified vulnerable systems, and once it was able to comprise one, it could easily move to the next,” Wilkinson said. “

“Ransomware is a cyber infection that demands money from the user in return for unlocking or returning the files it has locked up.”

Ransom demands for this incident were reported to be around $300. The payments had to be made with the digital currency Bitcoin which is nearly impossible to trace.

“Because Bitcoin is anonymous and untraceable, it’s very difficult to find where that money is going so you’re sending it to a numbered account and until you can put an identity with a numbered account, you can’t prosecute the person doing the crime,” Wilkinson said.

It’s still unknown as to who’s behind these attacks. Some researchers warn that copycat attacks could follow.