About global threat of WannaCrypt attacks

A significant number of customers have reported ransomware (Win32.WannaCrypt ) that was suspected to be introduced into their environment via email, this malware is using Social Engineering to target companies. Microsoft Anti-Malware products have been updated and detect the present version of this malware from definition version 1.243.290.0 onwards

Customer Guidance for WannaCrypt attacks

https://blogs.technet.microsoft.com/msrc/2017/05/12/customer-guidance-for-wannacrypt-attacks/

Impacted customers who were unpatched and infected will work through disaster recovery plans to rebuild and/or patch their systems.

1. Install Security Update MS17-010, to PREVENT further spread of the malware
https://technet.microsoft.com/en-us/library/security/ms17-010.aspx
2. Create the registry key to disable SMBv1 (used only if Security Update MS17-010 cannot be applied)
3. Updated Antivirus definitions should be applied (Microsoft Anti-Malware products detect the present version of this malware from definition version 1.243.290.0 onwards

For More details pls follow Windows Security Blog
https://blogs.technet.microsoft.com/mmpc/2017/05/12/wannacrypt-ransomware-worm-targets-out-of-date-systems/