Microsoft pushes security update to older versions of windows, provides guidance to customers.

Malwarebytes 3.0 and Malwarebytes Enterprise already protect against ransomware like WannaCrypt.

MCW highly recommends either one of these version to stay safe online.

https://www.malwarebytes.com/

Microsoft Article below.
https://docs.microsoft.com/en-us/msrc/customer-guidance-for-wannacrypt-attacks