According to Microsoft, the problem with SMBv3 affects the current Windows 10 versions 1903 and 1909 and the associated Windows servers. As an alternative to the update KB4551762, Microsoft has released a workaround, which, however, only works on SMB servers, i.e. on devices that offer SMB releases. One should switch off the compression of SMBv3 there.
This works with the registry value “DisableCompression”, which is located under “HKLM SYSTEM CurrentControlSet Services LanmanServer Parameters”. It should be set to the value “1”. Theoretically, the value can also be set on an SMB client, but according to Microsoft this does not work. A reboot should not be necessary for this. To cancel the setting, the value is set to “0”.
Admins can use the PowerShell. Microsoft documents the corresponding PowerShell commands on this page. We have a PowerShell script created that sets exactly these values.-
Microsoft also advises blocking remote access via TCP port 445 in the firewall if SMB is offered as an Internet share. This is a good idea anyway, but you are still vulnerable within the network – so it is more advisable to install the offered patch.
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