I am currently running a Windows Server 2016 Datacenter Virtual Machine in Azure. This server has 19 file shares on it. Each of these shares is devoted to a single customer of the company I work for. While troubleshooting a connection issue for a client, I found that all 19 of the file shares had been reconfigured so that the "Everyone" principal had full control. They where originally setup so that only the server administrator and a single, client specific account would have access to each file share.
1) Is there a way for me to determine how this happened? I did not have auditing configured on the server.
2) Is it possible that this happened without human intervention? Could some obscure windows bug have caused this?
3) How to I prevent this from happening again? I used the lastpass password generator when creating credentials for the group of people who administer this server. None of the accounts associated with customer file shares are authorized to remote into the server.