Run .exe inside Wix msi with admin rights - wix

Question

I am running the .exe file through a CustomAction in Wix. The executable is running but not with admin rights. Seems like i am doing everything correct but not sure what's going wrong. Here is the sample of my Custom Action
<CustomAction Id="RunExe" FileKey="Setup" ExeCommand="-switch" Execute="deferred" Return="check" Impersonate="no"/>
<InstallExecuteSequence>
<Custom Action="RunExe" Before="InstallFinalize">NOT Installed</Custom>
</InstallExecuteSequence>
The actual problem is that this .exe that is executed through ExeCommand is not able to access a registry key(HKCU\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders).
Running the msi as administrator solve the problem but i need a solution in which WIX should itself able to run the command as admin or atleast give a prompt to user.

Answer 1

A deferred custom action in a per machine install runs elevated with the system account. It's not clear what you mean by access to the HKCU key, but the HKCU key for an executable running with the system account is the system account's HKCU, not the installing user's HKCU. It would help if you said exactly what you are trying to achieve, because you might not need code at all. The install will update HKCU for the installing user if you use the registry features of WiX/MSI, so this may be a case of not really needing code at all.
It's also unclear why running the MSI as administrator solves the problem because that custom action will already be elevated in a per machine install with InstallPrivileges elevated. There is insufficient info in your post as tp your install context, but my guess is that you might be doing a per user install without InstallPrivileges elevated - that's one situation in which the MSI would run CAs under the installing user's account but they would not be elevated unless you elevate the entire install by doing as you said - runningthe MSI as administrator.