In Server Core, Windows Defender is enabled by default on Windows Server 2012 r2, without a GUI.

Does Windows Server have Windows Defender?

By default, Microsoft Defender Antivirus is installed and functional on Windows Server. Sometimes, the user interface (GUI) is installed by default, but the GUI is not required. You can use PowerShell, Group Policy, or other methods to manage Microsoft Defender Antivirus.

How do I know if Windows Defender is installed on my server?

Click Start and then click All Programs. 2. Look for Windows Defender in the list presented. If your computer is running Windows XP and you don’t see Windows Defender on the list, you can download the program for no charge.