wanna cry exploits vulnerability in windows os. 1st thing i.t. departments the world over send out updates immediately to users and clients to refresh software. the right thing to do in europe and america is stop, shut off windows os and don't use your pc's and laptops until non-peak hours. otherwise, europe and america will just contribute to the problem. it's friday anyway. just have a longer dinner (europe) and lunch (america) and use your ios or android mobiles and macs or chromebooks. for windows users, power up and do your software update (security fixes) after dinner. catch up on work if you have to at late hours. at your next work and home laptop refresh opportunity, get a macbook.