It has been reported that a researcher discovered that spread of the current worldwide ransomware attack can be halted after he registered the domain:
and built a sinkhole website that the malware could check. Reportedly the malware does not continue spreading if it can reach this site. HOWEVER, various antivirus websites/services are now reportedly adding that domain to their “bad domain” lists! If sites infected with this malware are unable to reach that domain due to their firewalls incorporating rules from antivirus sites that include a block for that domain, the malware will likely continue spreading across their vulnerable computers (which must also still be patched to avoid infection by similar exploits). Your systems MUST be able to access the domain above if this malware blocking trigger is to be effective, according to the current reports that I’m receiving!