win32_process create fails with Unknown failure for service account user - powershell

Question

I have a windows service account user, using which i'm trying to create a background process using the WMI win32_proces. But fails with Unknown Failure.
(Tried this with administrator, nonadmin, domain admin, domain nonadmin users. works fine)
$process = [WMICLASS]"\\$computername\ROOT\CIMV2:win32_process"
$processinfo = $process.Create("powershell.exe -WindowStyle Hidden test.ps1")
Write-Host $processinfo.returncode

Answer 1

As explained in this msdn blog post: Win32_Process.Create fails if user profile is not loaded, the WMI call is hardcoded to access the users profile through the registry.
If the user profile is not already loaded in HKU, WMI tries to load it into the registry using RegLoadKey.
This fails unless the user account in question have the following privileges on the local machine:
SeRestorePrivilege
SeBackupPrivilege
So, either
Grant these privileges to the account in question
Call LoadUserProfile for the user in question prior to calling Win32_Process.Create
Or use Start-Process instead of WMI!
# Set up service account credentials
$Username = "domain\svcaccount"
$Password = "7oPs3çürEûN1c0deZ"
$Credential = New-Object pscredential -ArgumentList $Username,$(ConvertTo-SecureString $Password -AsPlainText -Force)
# Establish a session on the remote machine
$RemoteSession = New-PSSession -ComputerName $computername -Credential $Credential
# Launch the process with Start-Process -LoadUserProfile
Invoke-Command -Session $RemoteSession {
Start-Process 'powershell.exe' -LoadUserProfile:$true -Argumentlist 'test.ps1' -WindowStyle Hidden
}
# Cleanup
Remove-PSSession -Session $RemoteSession
Remove-Variable -Name Username,Password,Credential

Answer 2

To Mathias suggestions in below comments:
Start-Process works in background only when invoked through interactive prompt. If run from a .ps1 script, the process created through start-process exits if the .ps1 script exits.
Inside your script. You can create a New-PSsession and then pass this session to invoke-command to trigger start-process.
But again to use New-PSsession and ExitPSSession, you must have Enable-PSRemoting and other setting enabled if you are lacking permissions. http://blogs.msdn.com/b/powershell/archive/2009/11/23/you-don-t-have-to-be-an-administrator-to-run-remote-powershell-commands.aspx