I have a business application (2 tier) in my environment and the backend is SQL database. I dont know what Platform is being used at the front end to develop this application, it could be Visual Studio. Somehow we end up in terminating the contract with the suppliers due to various reasons. I want to know that is there a way through which the vendors could access my servers and remove the application or stop access to it without me knowing. Please note that the vendor does not have any remote access to the server directly or through VPN or any other remote access tool and nor there are any license keys installed which required to be there for the application to work.
Also what would be the possibility of the application having some codes embedded with the expiry dates coded which will trigger the system to stop on certain dates? This is all assumptions but I am trying to protect and take necessary actions before the attack.