Spawning Processes into Interactive Sessions

Starting a Windows process using .NET is normally an easy thing. You call Process.Start() with a little setup, and the process runs. 

 But, that starts a process in the same Windows session as the thread that calls Process.Start(). 

 This, of course, doesn’t work for a Windows Service, since a service runs in a non-interactive Windows session (session 0). 

 For a Windows Session to spawn processes into interactive user sessions, a few steps are required. 

 Specifically, we have to: 

 

 

 Identify the target session 

 

 

 Retrieve the primary access token 

 

 

 Duplicate the primary token 

 

 

 Copy environment variables 

 

 

 Assign the working directory 

 

 

 Create the process 

 

 

 Here’s a library that I’ve pieced together, that abstracts the calls and ceremony needed to start a process in an arbitrary Window session, without handle leakage. 

 LeeWhite187/OGA.ProcessExtensions.Windows.Lib 

 It was adapted from ng-pe/cassia and murrayju/CreateProcessAsUser 

 See the repository page for example usage.