The WannaCry ransom ware attack. This type of ransom ware is nothing short of new
You can get some history from here
I will briefly state the website.
The first known malware extortion attack, the “AIDS Trojan” written by Joseph Popp in 1989.
So this is not really a new concept.
It started gaining popularity in 2013 and now is 2017 so we did have some time to prepare for it.
So what are the steps to preventing such an attack.
What I think is important. Is backup. Always backup your data. Put it in a cloud somewhere. Some service that actually keeps previous copies and also when you delete it keeps a copy. When files are encrypted their hash sum is different from the hash sum from their unencrypted copy so when they say cloud files are overwritten I think it cannot be unless maybe of course you do sync to be the same to make sure both sides are the same and the site to be synced with has files encrypted with crypto.
Another way that probably might work is disable the crypto service in windows. Usually it runs the crypto service of windows to encrypt the files so it might just work if the service is not installed in the first place to call.
As you have noticed it affected most of the windows systems. Another way about this might just be not to use windows.