This policy setting allows you to set the hardening level of the Windows Remote Management (WinRM) service with regard to channel binding tokens. If you enable this policy setting the WinRM service uses the level specified in HardeningLevel to determine whether or not to accept a received request based on a supplied channel binding token. If you disable or do not configure this policy setting you can configure the hardening level locally on each computer. If HardeningLevel is set to Strict any request not containing a valid channel binding token is rejected. If HardeningLevel is set to Relaxed (default value) any request containing an invalid channel binding token is rejected. However a request that does not contain a channel binding token is accepted (though it is not protected from credential-forwarding attacks). If HardeningLevel is set to None all requests are accepted (though they are not protected from credential-forwarding attacks).
Windows Components\Windows Remote Management (WinRM)\WinRM Service
At least Windows Vista