Cannot Write to the Registry under HKEY_LOCAL_MACHINE\Software

Question

I'm writing an application that needs to create a special user account hidden from login screens and the Control Panel users applet. By writing a DWORD value of 0 with the user name to the registry key below, I'm able to accomplish this goal:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\SpecialAccounts\UserList

The problem is that under Windows 7 with UAC on, no matter what I try, I cannot programmatically write a value to the key above.

It is my understanding that writing to certain keys this is not allowed on Windows 7 with UAC on, unless you are running with Administrative privileges. I've added an application manifest requestedExecutionLevel level="requireAdministrator" uiAccess="false", I accept the UAC prompt when my program is run, my account is a member of Administrators, yet I am still unable to write to the above registry key.

What more do I need to do? How is it possible, in any application configuration, to write keys and values under HKEY_LOCAL_MACHINE\SOFTWARE?

Further information ... When my program runs, no errors are thrown and it seems to write values. My guess is that Windows is virtualizing the location to which I am writing. I need to write to the actual location, not a virtual one, if I am to hide this special user account.

Answer 1

Probably the program runs as 32-bit program on the 64-bit operation system? In the case I recommend you to search the values which you created under Wow6432Node subkey of the HKEY_LOCAL_MACHINE\SOFTWARE.

You can read more about such kind of virtualization here. You can use KEY_WOW64_32KEY flag in some API to be able to work with full registry without virtualization.