It is vulnerable to numerous exploits (like BlueKeep or EternalBlue) that were discovered after 2013.
Microsoft officially ended extended support for Windows Server 2008 R2 on January 14, 2020 . If you are installing this July 2013 build today: It is vulnerable to numerous exploits (like BlueKeep
Because this is a "preactivated" version, the setup script usually runs a "loader" or a KMS emulator during the final stage of installation. Once you reach the desktop, the system should show as "Windows is activated" in the System properties. Vital Security Warning It is vulnerable to numerous exploits (like BlueKeep