Launching a .Net winforms application interactively from a service

Answer 1

In a word, "don't".

Services typically run with reduced privileges and NOT as the current user. As such, in Vista+ they're not allowed to interact with the users desktop. On top of all that, services get a null Window Station.

You used to be able to check a box that said something like "Allow to interact with the desktop" but not anymore. It's bad practice.

Your best bet is to create a helper app that runs in the users context and communicates with the service via a named pipe, LRPC or a socket, then have your helper app launch the program for the user. This is the way most anti-virus now works.

Also, read this whitepaper from Microsoft on the subject. Services can't run in anything other than session 0.

NOTE: a little research seems to indicate that you need to duplicate the token using something like this:

DuplicateTokenEx(hTokenNew,MAXIMUM_ALLOWED,NULL,
    SecurityIdentification,TokenPrimary,&hTokenDup);

Answer 2

It looks as if you're trying to break Session Isolation. Like Mystere Man said, I don't think it's the right thing to do.

http://support.microsoft.com/?scid=kb%3Ben-us%3B165194&x=5&y=3 might be useful if you really want to do this. In the code sample over there, they seem to initialize more thing than you do.

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EDIT If it's for debugging purposes, i-e VS 2008 step-in, just add a wait loop at the beginning, and launch VS with administrator rights. You can attach to your service process without encountering system isolation.

Answer 3

Like "Mystere Man" did my suggestion is use PIPE. This links is useful:

.NET 3.5 Adds Named Pipes Support
Interprocess Communication using Named Pipes in C#

Answer 4

Despite the evident hysteria there is nothing wrong with launching an application from a service into an interactive session provided it is done with the same privileges as the interactive user or lower. Since you are launching as the interactive user there can be no privilege escalation.

What you are doing does work. I suspect that the issue has something to do with your STARTUPINFO struct. You appear to be creating your sui on the stack but you don't show what you are doing with it. Are you initializing it to all 0s, if not you may be getting some garbage from the stack that is causing the window not to show or to show at some co-ordinates off the screen.