Installing a Windows Service as a user

Question

Hello,

I'm currently in the process of creating a Windows service application which will monitor changes to certain keys made in the HKEY_USERS registry. The way I do this is by collecting the SID of the current user. The issue I'm having is that its returning the administrators SID due to the service currently running as local system.

What I need the system to do is collect and return the SID of the currently logged in user (by this I dont mean the local service, local system or network service but the person whos logged into windows via the GINA), so what I need the service to do is run as that user. This will also allow the service to write back to the users network drive which is the intention of this program.

The issue I'm having is that when I try and install a user service using installutil.exe it asks for a username and password now I've tried my own credentials (I have an admin and non admin account) but it isn't having any of it plus I want the user to change depending on the person logging on and not to be fixed. Is there any way to do this?

Answer 1

The "The current user" assumption is a desktop Windows concept, and with Fast User Switching even that is not true anymore. The Windows services layer is rather common across desktop and server variants, and doesn't really deal well with this. It sits below the interactive sessions layer. One of the ways this manifests itself is in the ability to run services even if there are zero users logged in.

Answer 2

This all seems a bit confused. There can be any number of people logged on via remote desktops etc. If you as a service want to see their registry, you definitely wont get there via HKCU. If you want something like this, you should be using an autorun exe rather than a service. Anything like inspecting sessions and injecting stuff into them to access the loaded registry hive in the session is way overkill and not likely to be clean in any way.

Answer 3

You can find a process that runs with every user like explorer.exe then get the SID of the user that runs the process (you can use WMI like in the function here)