Although unsupported, it is possible to install Microsoft Security Essentials on a Windows Server 2012.
To do this, set the compatibility of the downloaded file to Windows 7, then start that file with the parameter /disableoslimit.
The installation goes without a problem, and as far as I can tell, there are no compatibility issues.
When deploying KMS on a Server 2012 R2, you may run into the error message saying nothing more but STATUS_SUCCESS.
The reason for this is that the KMS TCP Listening Port in the wizard, is by default set to 0, which is of course incorrect. Typing in the correct default value (1688) resolves the issue.