What is C:\Windows\System32\config\SYSTEM

I've seen several articles on C:\Windows\System32\config\SYSTEM being either corrupt or missing but I've always been curious as to what the purpose of this file is, as well as the purpose of remainder of files under C:\Windows\System32\config

Can someone please help me understand what these files are beyond telling me that they are system files.

1 Answer

%SystemRoot%\System32\config is the main location for system registry files in Windows NT.

Windows NT stores the registry in a binary file format which is meant to be loaded by the Registry Editor (%windir%\regedit.exe).

According to Wikipedia, the following system registry files are stored in: %SystemRoot%\System32\config:

• Sam (HKEY_LOCAL_MACHINE\SAM)
• Security (HKEY_LOCAL_MACHINE\SECURITY)
• Software (HKEY_LOCAL_MACHINE\SOFTWARE)
• System (HKEY_LOCAL_MACHINE\SYSTEM)
• Default (HKEY_USERS\.DEFAULT)
• Userdiff (not associated with a hive, used only during upgrades)

In addition to the registry files in %SystemRoot%\System32\config, there are also %USERPROFILE%\Ntuser.dat and %LocalAppData%\Microsoft\Windows\Usrclass.dat, which are user-specific.