Hello czql5v,
Thank you for posting in Microsoft Community forum.
As we know, Microsoft has ended the support for Windows Server 2008 and Windows Server 2008 R2 in 2020.
End of support for Windows Server 2008 and Windows Server 2008 R2 | Microsoft Learn
And Windows Server 2012 and Windows Server 2012 R2 will end on October 10, 2023.
Windows Server 2012 and 2012 R2 reaching end of support - Microsoft Lifecycle | Microsoft Learn
So maybe Microsoft will not have a Server Hardening plan for W2008 and/or W2012 versions.
I suggest you can consider from other aspects, such as Firewalls, intrusion detection, vulnerability scanning systems, installing antivirus software, and much more on W2008 and/or W2012 versions.
And you had better make legacy App compatible with newer versions anytime in future (not in the near future.).
Meanwhile, if you need a service support for further help and support from Microsoft some day in future, please check link below.
Global Customer Service phone numbers - Microsoft Support
I hope the information above is helpful.
If you have any question or concern, please feel free to let us know.
Best Regards,
Daisy Zhou