The malicious ransomware WannaCry, that has hit about 150 countries around the world, is said to be mutating.

According to the cybersecurity industry on Monday, about 280 new versions of the WannaCry malware have been detected since it spread around the world, in earnest, on Friday.

A 22-year-old UK security researcher activated the “kill switch” to stop the ransomware attack, but new versions emerged soon after.

The malicious program infects computers when it connects to an unregistered Web domain included in the program. The UK researcher noticed it and activated the kill switch by registering the domain. However, the malware immediately mutated by using different domains to avoid the kill switch.