Microsoft Security Essentials (Windows Defender) cannot be installed on Windows Server Operating Sytstems, like Server 2012.
Using this easy guide, will allow you to install and use Microsoft Security Essentials (MSE) on any Server OS.
1.Download Security Essentials:
2. Right click on Downloaded MSE and click “Properties”. Go to “Compatibility” Tab and set compatibility for “Windows 7”
3. Run a Command Prompt Window (CMD) and browse to downloaded MSE
4.Enter Command “MSEInstall /disableoslimit” (MSEInstall is the downloaded installer file name)
5.Finished, the installer will start and allow to install MSE