CLR Hosting: running dotNet binary in C/C++ & rewrite from .NET(4+) COM interface

clrHosting_v4.0.cpp

// CLR Hosting, by aaaddress1@chroot.org
//
// it's a new edition rewrite for .NET(4+) COM interface 
// original from github.com/etormadiv/HostingCLR
//             & blog.xpnsec.com/hiding-your-dotnet-etw
// 
// this PoC supports the following .NET entry:
// >>>> static void Main(string[] args);
//
#include <stdio.h>
#include <windows.h>
#include <mscoree.h>
#include <metahost.h>
#pragma comment(lib, "MSCorEE.lib")
#pragma warning( disable:4996 )

// Import mscorlib.tlb (Microsoft Common Language Runtime Class Library).
#import "mscorlib.tlb" auto_rename
using namespace mscorlib;

bool readBinFile(const char fileName[], char*& bufPtr, DWORD& length) {
	if (FILE* fp = fopen(fileName, "rb")) {
		fseek(fp, 0, SEEK_END);
		length = ftell(fp);
		bufPtr = new char[length + 1];
		fseek(fp, 0, SEEK_SET);
		fread(bufPtr, sizeof(char), length, fp);
		return true;
	}
	else return false;
}

ICorRuntimeHost* getCorRtHost_byVersion(LPCWSTR sz_runtimeVersion) {
	ICLRRuntimeInfo* pRuntimeInfo = NULL;
	ICorRuntimeHost* pRuntimeHost = NULL;
	ICLRMetaHost* pMetaHost = NULL;
	BOOL bLoadable;

	/* Get ICLRMetaHost instance */
	if (FAILED(CLRCreateInstance(CLSID_CLRMetaHost, IID_ICLRMetaHost, (VOID**)&pMetaHost)))
	{
		printf("[!] CLRCreateInstance(...) failed\n");
		return NULL;
	}
	else printf("[+] CLRCreateInstance(...) succeeded\n");

	/* Get ICLRRuntimeInfo instance */
	if (FAILED(pMetaHost->GetRuntime(sz_runtimeVersion, IID_ICLRRuntimeInfo, (VOID**)&pRuntimeInfo))) {
		printf("[!] pMetaHost->GetRuntime(...) failed\n");
		return NULL;
	}
	else printf("[+] pMetaHost->GetRuntime(...) succeeded\n");

	/* Check if the specified runtime can be loaded */
	if (FAILED(pRuntimeInfo->IsLoadable(&bLoadable)) || !bLoadable) {
		printf("[!] pRuntimeInfo->IsLoadable(...) failed\n");
		return NULL;
	}
	else printf("[+] pRuntimeInfo->IsLoadable(...) succeeded\n");

	/* Get ICorRuntimeHost instance */
	if (FAILED(pRuntimeInfo->GetInterface(CLSID_CorRuntimeHost, IID_ICorRuntimeHost, (VOID**)&pRuntimeHost))) {
		printf("[!] pRuntimeInfo->GetInterface(...) failed\n");
		return NULL;
	}
	else printf("[+] pRuntimeInfo->GetInterface(...) succeeded\n");

	/* Start the CLR */
	if (FAILED(pRuntimeHost->Start())) {
		printf("[!] pRuntimeHost->Start() failed\n");
		return NULL;
	}
	else printf("[+] pRuntimeHost->Start() succeeded\n");
	return pRuntimeHost;
}

_AppDomainPtr getDefaultDomain(ICorRuntimeHost* pRuntimeHost) {
	IUnknownPtr pAppDomainThunk = NULL;
	if (FAILED(pRuntimeHost->GetDefaultDomain(&pAppDomainThunk))) {
		printf("[!] pRuntimeHost->GetDefaultDomain(...) failed\n");
		return NULL;
	}
	else printf("[+] pRuntimeHost->GetDefaultDomain(...) succeeded\n");

	/* Equivalent of System.AppDomain.CurrentDomain in C# */
	_AppDomainPtr pDefaultAppDomain = NULL;
	if (FAILED(pAppDomainThunk->QueryInterface(__uuidof(_AppDomain), (LPVOID*)&pDefaultAppDomain))) {
		printf("[!] pAppDomainThunk->QueryInterface(...) failed\n");
		return NULL;
	}
	else printf("[+] pAppDomainThunk->QueryInterface(...) succeeded\n");
	return pDefaultAppDomain;
}

_AssemblyPtr getAssembly_fromBinary(_AppDomainPtr pDefaultAppDomain, LPBYTE rawData, ULONG lenRawData) {
	_AssemblyPtr pAssembly = NULL;
	SAFEARRAY* pSafeArray = SafeArrayCreate(VT_UI1, 1, new SAFEARRAYBOUND{ lenRawData , 0 });

	void* pvData = NULL;
	if (FAILED(SafeArrayAccessData(pSafeArray, &pvData))) {
		printf("[!] SafeArrayAccessData(...) failed\n");
		return -1;
	}
	else printf("[+] SafeArrayAccessData(...) succeeded\n");

	memcpy(pvData, rawData, lenRawData);
	if (FAILED(SafeArrayUnaccessData(pSafeArray))) {
		printf("[!] SafeArrayUnaccessData(...) failed\n");
		return NULL;
	}
	else printf("[+] SafeArrayUnaccessData(...) succeeded\n");

	/* Equivalent of System.AppDomain.CurrentDomain.Load(byte[] rawAssembly) */
	if (FAILED(pDefaultAppDomain->raw_Load_3(pSafeArray, &pAssembly))) {
		printf("[!] pDefaultAppDomain->Load_3(...) failed\n");
		return NULL;
	}
	else printf("[+] pDefaultAppDomain->Load_3(...) succeeded\n");
	return pAssembly;
}

SAFEARRAY* newArguments(int argc, wchar_t** argv) {
	VARIANT args;
	args.vt = VT_ARRAY | VT_BSTR;
	args.parray = SafeArrayCreate(VT_BSTR, 1, new SAFEARRAYBOUND{ ULONG(argc) , 0 });
	for (int i = 0; i < argc; i++) SafeArrayPutElement(args.parray, (LONG*)&i, SysAllocString(argv[i]));

	SAFEARRAY* params = SafeArrayCreate(VT_VARIANT, 1, new SAFEARRAYBOUND{ 1, 0 });

	LONG indx = 0;
	SafeArrayPutElement(params, &indx, &args);
	return params;
}

ICorRuntimeHost* bruteforce_CLRhost() {
	ICLRMetaHost* metaHost = NULL;
	IEnumUnknown* runtime = NULL;
	ICLRRuntimeInfo* runtimeInfo = nullptr;
	DWORD bytes;
	if (CLRCreateInstance(CLSID_CLRMetaHost, IID_ICLRMetaHost, (LPVOID*)&metaHost) != S_OK) {
		printf("[x] Error: CLRCreateInstance(..)\n");
		return NULL;
	}

	if (metaHost->EnumerateInstalledRuntimes(&runtime) != S_OK) {
		printf("[x] Error: EnumerateInstalledRuntimes(..)\n");
		return NULL;
	}
	auto frameworkName = (LPWSTR)LocalAlloc(LPTR, 2048);
	IUnknown* enumRuntime = nullptr;
	// Enumerate through runtimes and show supported frameworks
	while (runtime->Next(1, &enumRuntime, 0) == S_OK) {
		if (enumRuntime->QueryInterface<ICLRRuntimeInfo>(&runtimeInfo) == S_OK) {
			if (runtimeInfo != NULL) {
				runtimeInfo->GetVersionString(frameworkName, &bytes);
				wprintf(L"[*] Supported Framework: %s\n", frameworkName);
	
			}
		}
	}
	wprintf(L"[*] Current Used Framework: %s\n", frameworkName);
	return getCorRtHost_byVersion(frameworkName);
}

int wmain(int argc, wchar_t* argv[]) {

	PCHAR ptrBinary; DWORD lenBinary;
	if (!readBinFile("C:/dotNet_PoC.exe", ptrBinary, lenBinary))
		return -1;

	printf(" --- Try to Fetch .NET Framework v2.0 ---\n");
	ICorRuntimeHost* pRuntimeHost = getCorRtHost_byVersion(L"v2.0.50727");
	pRuntimeHost = 0;

	printf("\n --- Enumerate Available CLR Runtime ---\n");
	if (!pRuntimeHost) if ((pRuntimeHost = bruteforce_CLRhost()) == 0)
		return -1;
	
	printf("\n --- Execute .NET Module ---\n");
	_MethodInfoPtr pMethodInfo = NULL;
	// fetch the default domain
	if (auto pDefaultAppDomain = getDefaultDomain(pRuntimeHost))
		// load .net module into CLR (PE binary)
		if (_AssemblyPtr pAssembly = getAssembly_fromBinary(pDefaultAppDomain, LPBYTE(ptrBinary), (lenBinary)))
			//A ssembly.EntryPoint Property
			if (FAILED(pAssembly->get_EntryPoint(&pMethodInfo))) {
				printf("[!] pAssembly->get_EntryPoint(...) failed\n");
				return -1;
			}
			else printf("[+] pAssembly->get_EntryPoint(...) succeeded\n");

	/* EntryPoint.Invoke(new string[] { argv_1, argv_2, argv_3, ... } ) */
	if (HRESULT hr = pMethodInfo->raw_Invoke_3(VARIANT(), newArguments(argc, argv), &VARIANT()) < 0) {
		printf("[!] pMethodInfo->Invoke_3(...) failed, hr = %X\n", hr);
		return -1;
	}
	else printf("[+] pMethodInfo->Invoke_3(...) succeeded\n");
	return 0;
}