A wide-spread ransomware attack, known as "Petya," targets out-of-date Windows devices. Given the severity of this threat, Microsoft recommends that you immediately update your Windows devices. You should:
Turn on automatic updates and verify your devices are up to date.
In Windows 10, go to Settings > Update & Security . You'll see your update status there.
In Windows 8.1, go to Settings > Change PC Settings > Update and recovery.
In Windows 7, go to Control Panel > Windows Update.
Ensure you have the latest antivirus updates for your antivirus product. If you use Windows Defender and Windows automatic updates are on, you'll automatically get the latest updates.
For more information, see microsoft.com/protect/pc