A sample DLL ready to be injected into a service to exec a script. This is called DLL Hijacking if you want to learn more about this. http://www.thewindowsclub.com/dll-hijacking
Place a script file : script.bat into C:\temp\ and launch the vulnerable service. If you have different path, change the path and recompile the project. After the Dll is loaded the code into script.bat will be executed.
I place two compiled dll x64.dll and x86.dll ready to execute a script on the C:\temp\ folder as an example.