c# - Starting application from service running as SYSTEM that can interact with the user

Question

I currently have a single application that needs to be started from a windows service that i am coding in .net 3.5. This application is currently running as the user who ran the service, in my case the SYSTEM user. If running as the SYSTEM user it does not show the application to the users desktop. Thoughts? advice?

//constructor
    private Process ETCHNotify = new Process();

//StartService()     
    ETCHNotify.StartInfo.FileName = baseDir + "\EtchNotify.exe";
    ETCHNotify.StartInfo.UseShellExecute = false;

//BackgroundWorkerThread_DoWork()
    if (!systemData.GetUserName().Equals(""))
    {
        // start ETCHNotify
        try {
            ETCHNotify.Start();
        }
            catch (Exception ex)
        {
            systemData.Run("ERR: Notify can't start: " + ex.Message);
        }
    }

I only execute the try/catch if the function i have written GetUserName() (which determines the username of the user running explorer.exe) is not null

again to reiterate: desired functionality is that this starts ETCHNotify in a state that allows it to interact with the currently logged in user as determined by GetUserName()

Answer 1

Collage of some post found around (this and this)

Note that as of Windows Vista, services are strictly forbidden from interacting directly with a user:

Important: Services cannot directly interact with a user as of Windows Vista. Therefore, the techniques mentioned in the section titled Using an Interactive Service should not be used in new code.

This "feature" is broken, and conventional wisdom dictates that you shouldn't have been relying on it anyway. Services are not meant to provide a UI or allow any type of direct user interaction. Microsoft has been cautioning that this feature be avoided since the early days of Windows NT because of the possible security risks.

There are some possible workarounds, however, if you absolutely must have this functionality. But I strongly urge you to consider its necessity carefully and explore alternative designs for your service.

Use WTSEnumerateSessions to find the right desktop, then CreateProcessAsUser to start the application on that desktop (you pass it the handle of the desktop as part of the STARTUPINFO structure) is correct.

However, I would strongly recommend against doing this. In some environments, such as Terminal Server hosts with many active users, determining which desktop is the 'active' one isn't easy, and may not even be possible.

A more conventional approach would be to put a shortcut to a small client app for your service in the global startup group. This app will then launch along with every user session, and can be used start other apps (if so desired) without any juggling of user credentials, sessions and/or desktops.