Here's a 'guide' from 2012 http://carnal0wnage.attackresearch.com/2012/04/privilege-esc...
And here's a 'fix' from microsoft: https://social.technet.microsoft.com/Forums/windows/en-US/a3...
If you can alter one system file then you can alter all system files. So even if this got "fixed," then another program would be replaced, a service, or the login screen itself.
The only actual fix is to protect the Windows installation itself, this can be accomplished through full disk encryption (e.g. Bitlocker) in combination with uEFI secure boot.
To be honest I roll my eyes when people post "exploits" like this. It just shows that people have no core understanding of computer security from the ground on up.
As an aside this exact exploit would work perfectly on a Linux (e.g. Ubunutu) system that didn't implement full disk encryption.