Enable the highest level Cloud Protection on Windows Defender on Windows 10 (1703) Creators Update

Add the following two values in the registry by using CMD with administrator privilege:

REG ADD "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\Spynet" /v SpynetReporting /t REG_DWORD /d 2

REG ADD "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender\MpEngine" /v MpCloudBlockLevel /t REG_DWORD /d 2

Reference:

http://www.hksilicon.com/kb/articles/1346870

https://docs.microsoft.com/en-us/windows/threat-protection/windows-defender-antivirus/enable-cloud-protection-windows-defender-antivirus

https://www.ghacks.net/2017/05/26/set-windows-defender-antivirus-blocking-to-high-on-windows-10/

https://www.windowscentral.com/how-change-windows-defender-antivirus-cloud-protection-level-windows-10

https://docs.microsoft.com/en-us/windows/threat-protection/windows-defender-antivirus/specify-cloud-protection-level-windows-defender-antivirus