Hackers who infected over 200,000 computers with the
The ransomware – which locks files on a computer and demands payment in bitcoin to unlock them – was able to exploit a vulnerability known as "Eternal Blue". This security flaw was unknown to Microsoft for a while but used by the NSA.
But last month, a group called Shadow Brokers managed to steal the files and leak them online. Microsoft had a so-called patch for this in March, but many of the computers affected by the WannaCry worm hadn't updated.
"As governments all over the world invest in finding weaknesses in computer systems we are going to continue to see organizations exploiting these," James Chappell, chief technology officer at London-based
"In this case, these weaknesses were made public which is why this has really happened. We have not seen this publication of these exploits being used in this way before and I suspect we will see many more of those to come."