Computer security experts at the Bkav Corporation, one of Vietnam's leading antivirus sofware providers, advised Microsoft users to turn on Windows Updates, back up all important data in more than one place, and keep their antivirus software up to date. WannaCry took control of users' files and demanded 300-600 USD payments to restore access. More than 200,000 computers in 150 countries have been impacted since Friday. The cyber-attack's global reach is "unprecendented", according to Europol.