WannaCry’s rapid spread, enabled by its implementation of a Windows vulnerability stolen from an intelligence agency, was suddenly halted when security researchers registered an internet domain name embedded in the code – a routine research procedure that, inadvertently, tripped a “kill switch” subroutine in the malware, causing it to stop infecting computers. A small number of variants released in the following days, using new kill switch domains, were shut down using the same method. By the time the kill switch domain had any effect, the malware had already wrought a lot of destruction. But the kill switch, surprisingly, didn’t mean an end to WannaCry, even though WannaCry was updated and re-released only twice a few days after the first infection. In fact, WannaCry detection appear to be at an all-time high, surpassing the number of detection of older worm malware such as Conficker. The malware continues to infect computers worldwide.