VB6: How to temporarily elevate to administrator privileges

Hi ttobin333,

Yes choose any GUID value but make sure you don't change it after you install the registry locations.

When you create ActiveX.dll it has some static information that won't change after compiling. I recommend that when you are ready for deployment make a (release) build by changing the compile options for the activex.dll to (binary compatability) after you compile use the COM dumper to get the CLSID,IID. It's important that these values will never change and will be the same on every system (binary compatability) makes sure this happens.

What you place within the activex.dll is your administrative tasks. This is anything that needs to be run as administrator to work.
The simplest example of this would be trying to create a file on the ROOT drive of C:\ etc..

To make things easier for you and not get to much into classes you can think of the class.cls as a module where some restrictions apply. The basic concept here is to know which operations you will perform that require administrative access and add these to that class instead of your main process.

The only mis-leading part about this whole elevation process is installing the registry locations during the install process. In VB6 by default you can't execute code when you register the activex.dll. However in C++ you can add code to the DllRegisterServer stub and whenver you register the C++ dll it will execute the code inside that stub. Because VB6 can't do this you have to make a workaround.

The best options:
1) Create a C++ MFC DLL that it's only purpose is to install these registry locations. You would first register the VB activex.dll then you would register the C++ MFC dll which will install the registry entries required for the VB activex dll.

2) You can create small program that runs as administrator as the final step of the install process that will install these registry locations. This can be as simple as a form that would indicate to the user "To help better your experience on windows Vista such and such application needs install additional information. Click OK to continue.
Keep in mind that the registry entries need to be installed "AFTER" you register the VB activex.dll.

3) You can create a registry script that installs this entries.

As you can see the only downside here is that VB6 can't execute code when the DLL is registered so you have to use one of the above options instead. This isn't to much of a problem if you take a proffesional approach for Option 2. Option 1 may be difficult but is probrably the best although it requires that you know how to call the registry API's in C++.

One thing I left out of the article and I think the project example is that before you actually elevate you should check that the process is running with standard user access token.


Now before we go any further it's prob a good idea to see what is failing on your side. It's possible you don't need to use any of this and that your download fails because you are being denied access to that folder location. For this purpose it's recommended that all files be placed in Application Data because even standard user can read/write at this location. It's only specific tasks that should really be put into place using this method on vista.


Remember that these entire steps are targeted towards working with UAC under vista and your application should be responsible for determine the OS version act accordingly. ex..
If XP OS use impersonations if user running as standard user.

The small example snippet attached is what it should really look like for application calls.

Dim MyTask As AdminTask
  
  '// Before you elevate first check if it's required!
  If VistaTasks.IsProcessRunningAsAdmin Then
  
    '// We don't need to elevate we can do the task!
    MyTask.CreateFileRoot
    
  Else
  
    '// We must elevate the process role is not administrator.
    
    If VistaTasks.CoCreateInstanceAsAdmin(Me.hWnd, _
        "{55CC8F68-356E-45E7-91EE-062C8D909E77}", _
        "{477D2A0F-3B5D-4AB2-937C-5E663BE66C57}", _
        MyTask) = 0 Then   '//S_OK
        
      '// run the admin task!
      MyTask.CreateFileRoot
      
    End If
    
    
  End If
  
  '// de-reference
  If Not MyTask Is Nothing Then
    Set MyTask = Nothing
  End If

                                              

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