I have synchronized a part of our on-premise AD to Azure AD. The users have been created correctly.
Now I'm are able to log into all of our Azure VMs which belong to the AD domain using RDP, but without the need to enter the user's password! Indeed, I have to leave the password empty in order to be able to login. Otherwise, RDP login for the synced users is impossible.
However, what really worries me is the fact that user A can log in as user B on any of the Azure VMs without entering the password just by passing the username! How can that be?