Giving Application Rights to Change Registry in Windows XP

Question

I don't have XP on any of my machines. My efforts to get a small application to run as Administrator in Vista and Windows 7 work. However one of my testers is reporting that on Windows XP he is getting the following exception:

System.UnauthorizedAccessException: Access to the registry key 'HKEY_CLASSES_ROOT\.ad2' is denied.
   at Microsoft.Win32.RegistryKey.Win32Error(Int32 errorCode, String str)

The code I am using to run the application that tries to write to the registry is:

var proc = new ProcessStartInfo {
                UseShellExecute = true,
                WorkingDirectory = Environment.CurrentDirectory,
                FileName = Path.Combine(Application.StartupPath, "ADEFileAssociator.exe"),
                Verb = "runas"
            };

            try {
                Process.Start(proc);
            }
            catch {
                MessageBox.Show("Failed to start File Associator", "Process Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
                return;
            }

This works fine for Vista and Win7 opening the UAC dialog. If the user accepts to run then the registry is updated on these versions. I assumed that the same would work for XP. Clearly I was wrong. So my question is 'what else do I need to do to get my app to write to the registry in XP?

Answer 1

For XP you don't have UAC and so you can't use the runas verb. Instead the best you can do is set the UserName and Password properties of ProcessStartInfo . This pretty much sucks because you'd have to show an authentication dialog or hard code the values!

If I were in your position I'd look very hard for a way to can avoid having to gain admin rights? If that fails then I'd probably make it a pre-condition for your app to run on XP that the user had admin rights.