Security researcher says he's figured out how to decrypt WannaCry

The ransomware WannaCry has infected hundreds of thousands of computer systems around the globe, but a security researcher claims he's figured out how to beat it. 

In some cases, that is.

Adrien Guinet says that he was able to decrypt a ransomwared computer running Windows XP in his lab by discovering the prime numbers that make up the WannaCry private key. The private key is what a ransomware victim would need to buy off his attackers in order to regain access to his own files, but Guinet says he was able to do this without paying any Bitcoin ransom.