Run application without ADMIN rights via Process.Start from elevated application

Question

I have a VB.NET application that interfaces with MS-Outlook and, to do it, it must run without ADMIN priviledges. Everything is OK.

The problem occurs after the "LiveUpdate" module, a separated application running with ADMIN priviledges, ends its update and loads again the main application. This load is performed using:

 Process.Start(MyApp.exe)

but when "MyApp" loads, it cannot interface anymore with MS-Outlook, which refuse that interface sending a typical message of programs running at different UAC priviledges. I guess when LiveUpdate executes the Process.Start, the command goes with its same priviledge (ADMIN).

Facts:

1. The Liveupdate MUST run in ADMIN but MyApp MUST run in NORMAL way.
2. Both has its own MANIFEST, but it seems the call above bypass the Manifest of MyApp - which is set "as Invoke" as default.
3. If I close MyApp and run it again manually, everything goes OK.
4. Some clients has USER/PASSWORD, others do not have it (Windows loads automatically with no User/Password dialog).
   5.The application runs in Windows Vista, 7, 8, 8.1 and 10.

So, is there some way to "Process.Start" an application discarding the ADMIN priviledge from the caller (LiveUpdate)?

The usage of User/Password during this call is not an option I guess... Thanks!

Answer 1

Here is what I found: you can start a de-elevated process from an elevated software by running it trough explorer.exe. This method should work with everyone except for users that are admin, (not user administrator, but system administrator). I found this info here.

For the code part of it, it looks like this: (credit for this goes to plutonix; follow the link above)

Dim proc = New Process
proc.StartInfo.UseShellExecute = True
proc.StartInfo.WindowStyle = ProcessWindowStyle.Normal
proc.StartInfo.WorkingDirectory = mypath

If chkAdmin.Checked Then                    ' run this app as admin
    proc.StartInfo.FileName = myApp
    proc.StartInfo.WorkingDirectory = mypath
    proc.StartInfo.Verb = "runas"           ' run "me" as admin
    proc.StartInfo.Arguments = ""
Else                                        ' run explorer w/app as arg
    ' de-elevate new app instance to run de-elevated
    proc.StartInfo.FileName = Path.Combine(windir, "explorer.exe")  
    proc.StartInfo.Verb = ""                ' important!
    proc.StartInfo.Arguments = myApp        ' send the child app name as arg
End If

proc.Start()

I have not tested this out myself, but it should work correctly. (Again all credit for this goes to user: plutonix)