Elevating process privilege programatically?

Question

I'm trying to install a service using InstallUtil.exe but invoked through Process.Start. Here's the code:

ProcessStartInfo startInfo = new ProcessStartInfo (m_strInstallUtil, strExePath);
System.Diagnostics.Process.Start (startInfo);

where "m_strInstallUtil" is the fully qualified path and exe to InstallUtil.exe and "strExePath" is the fully qualified path/name to my service.

Running the command line syntax from an elevated command prompt works; running from my app (using the above code) does not. I assume I'm dealing with some process elevation issue, so how would I run my process in an elevated state? Do I need to look at ShellExecute for this?

This is all on Windows Vista. I am running the process in the VS2008 debugger elevated to admin privilege.

I also tried setting "startInfo.Verb = "runas";"--it didn't seem to solve the problem.

Answer 1

You should use Impersonation to elevate the state.

WindowsIdentity identity = new WindowsIdentity(accessToken);
WindowsImpersonationContext context = identity.Impersonate();

Don't forget to undo the impersoanted context when you are done.

Answer 2

You can indicate the new process should be started with elevated permissions by setting the Verb property of your startInfo object to 'runas', as follows:

startInfo.Verb = "runas";

This will cause Windows to behave as if the process has been started from Explorer with the "Run as Administrator" menu command.

This does mean the UAC prompt will come up and will need to be acknowledged by the user: if this is undesirable (for example because it would happen in the middle of a lengthy process), you'll need to run your entire host process with elevated permissions by embedding the appropriate manifest in your application to require the 'highestAvailable' execution level: this will cause the UAC prompt to appear as soon as your app is started, and cause all child processes to run with elevated permissions without additional prompting.

Edit: I see just just edited your question to state that "runas" didn't work for you. That's really strange, as it should (and does for me in several production apps). Requiring the parent process to run with elevated rights by embedding the manifest should definitely work, though.

Answer 3

According to this article: http://msdn.microsoft.com/en-us/magazine/cc163486.aspx, only ShellExecute checks the embedded manifest and prompts the user for elevation if needed, while CreateProcess and other APIs don't. Hope it helps.