C# DLL from VBScript, no regasm

Question

Is it possible to access a C# DLL's method from VBScript without registering it with regasm? I will be creating the DLL so pretty much any exotic requirement to make it visible to VBScript, I can do...

I have read here that it might be possible to use GetObject from VBScript to achieve this, but I have tried that with no success... Is there anything else I need to do aside from making the DLL "COM visible" to make this work?

The reason why I need to avoid regasm is that it requires admin rights, and I need to deploy this DLL "silently" to many clients that may or may not have admin rights.

Answer 1

No, registration is required, the only way that the script interpreter can find the DLL that contains the ProgId that you use in the script's CreateObject() call. Isolated COM with a manifest doesn't work, you can't modify the manifest for the script interpreter.

There is a technical solution, you can write registry keys in the HKCU registry hive without acquiring UAC elevation. The Regasm.exe tool always writes them in the HKLM hive. That registers the assembly as well, but only for the user that runs Regasm.exe. It is however pretty painful and easy to get wrong, you have to write your own registration method and apply the [ComRegisterFunction] attribute. It is now your job to use the RegistryKey class to set the keys. Same for the [ComUnregisterFunction], it should delete the keys again. There are a lot of bad examples out on the interwebs, best way to get this right is to use SysInternals' ProcMon to observe the registry keys that get written when you use Regasm.exe normally, then reproduce that in your own code, using HKCU instead.

Do note the other side of that medal, you are in fact making configuration changes to the machine that allows arbitrary code to run. Trying to hide that doesn't do the user any favors and should never be considered if you honor the user's desire to keep the machine safe and predictable. UAC is not there to stop you from making changes, it is only there to inform the user about it.

Answer 2

The accepted answer is incorrect that registration is required to use a DLL. You can use the GetObject() method instead of the CreateObject() method as shown in my answer to this question.

Using DLLs in VBScript