This was a "cyber attack" like driving through a minefield is a "suicide bomb."
MS has issued emergency patches for unsupported versions of Windows.
Mitigations for WannaCry
Get your patch here if you need it.
MS Security Bulletin Details
- Windows Server 2003 -> 2008
- Windows XP -> Windows 8
- Windows POSReady and WES09
If you have been affected
As of right now there is no way to decrypt your data and the perpetrators are apparently not able to hand out encryption keys even if you pay the ransom due to them not being able to track 'users' as it were and are unable to link keys to specific infection instances.
You will have to restore from backups.
Updated Wiki Gist
You can keep up with the latest developments covering WanaCrypt0r on this wiki gist now.
It's being updated as more developments come in. It's currently still just a fraction of what we expect to see.
Well written summary on WannaCrypt0r by Troy Hunt
Index of public servers affected by WCRY (as of yet ~11'200 results) some are just tips on how to google for affected servers