逆向工程核心原理——第三十二章

计算器显示中文数字

此实验中使用的代码只适用于x86系统。

本章讲解API钩取技术时将以Windows计算器（ calc.exe）为示例，向计算器进程插人用户的
DLL文件，钩取IAT的user32.SetWindowTextW() API地址。

SetWindowTextW() API的作用是显示计算器中的数字，而我们会将这个数字改为中文数字。

我们知道，当程序需要调用源程序之外的函数时，需要访问导入表(IAT)，IAT中存放着需要调用的函数的地址，而这次的实验，我们就需要钩出这个地址，替换成别的地址，从而使阿拉伯数字变为汉字数字。

我们在图中可以看到：

这里计算器(cala.exe)运行到01002628时调用user32.dll，调用完成后回到cala.exe

而我们修改后的运行顺序为：

EXE:

//InjectDll.exe

#include "stdio.h"  
#include "windows.h"  
#include "tlhelp32.h"  
#include "winbase.h"  
#include "tchar.h"  
#include<iostream>
using namespace std;

void usage()
{
	printf("
InjectDll.exe by ReverseCore
"
		"- USAGE : InjectDll.exe <i|e> <PID> <dll_path>

");
}


BOOL InjectDll(DWORD dwPID, LPCTSTR szDllName)
{
	HANDLE hProcess, hThread;
	LPVOID pRemoteBufferData;  //远程进程中的内存
	DWORD dwBufSize = (DWORD)(_tcslen(szDllName) + 1) * sizeof(TCHAR);
	LPTHREAD_START_ROUTINE pThreadProc;

	if (!(hProcess = OpenProcess(PROCESS_ALL_ACCESS, FALSE, dwPID)))
	{
		DWORD dwErr = GetLastError();
		return FALSE;
	}

	//申请内存 可读可写
	pRemoteBufferData = VirtualAllocEx(hProcess, NULL, dwBufSize, MEM_COMMIT, PAGE_READWRITE);

	//像内存写入dll路径
	WriteProcessMemory(hProcess, pRemoteBufferData, (LPVOID)szDllName, dwBufSize, NULL);

	//获得loadlibraryw地址
	pThreadProc = (LPTHREAD_START_ROUTINE)GetProcAddress(GetModuleHandle(L"kernel32.dll"), "LoadLibraryW");

	//创建远程线程
	hThread = CreateRemoteThread(hProcess, NULL, 0, pThreadProc, pRemoteBufferData, 0, NULL);
	WaitForSingleObject(hThread, INFINITE);

	CloseHandle(hThread);
	CloseHandle(hProcess);

	return TRUE;
}


BOOL EjectDll(DWORD dwPID, LPCTSTR szDllName)
{
	BOOL bMore = FALSE, bFound = FALSE;
	HANDLE hSnapshot, hProcess, hThread;
	MODULEENTRY32 me = { sizeof(me) };
	LPTHREAD_START_ROUTINE pThreadProc;

	if (INVALID_HANDLE_VALUE == (hSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPMODULE, dwPID)))
	{
		return FALSE;
	}


	bMore = Module32First(hSnapshot, &me);
	for (; bMore; bMore = Module32Next(hSnapshot, &me))
	{
		if (!_tcsicmp(me.szModule, szDllName) || !_tcsicmp(me.szExePath, szDllName))
		{
			bFound = TRUE;
			break;
		}
	}

	if (!bFound)
	{
		CloseHandle(hSnapshot);
		return FALSE;
	}

	if (!(hProcess = OpenProcess(PROCESS_ALL_ACCESS, FALSE, dwPID)))
	{
		CloseHandle(hSnapshot);
		return FALSE;
	}

	pThreadProc = (LPTHREAD_START_ROUTINE)GetProcAddress(GetModuleHandle(L"kernel32.dll"), "FreeLibrary");
	hThread = CreateRemoteThread(hProcess, NULL, 0, pThreadProc, me.modBaseAddr, 0, NULL);
	WaitForSingleObject(hThread, INFINITE);

	CloseHandle(hThread);
	CloseHandle(hProcess);
	CloseHandle(hSnapshot);

	return TRUE;
}


DWORD _EnableNTPrivilege(LPCTSTR szPrivilege, DWORD dwState)
{
	DWORD dwRtn = 0;
	HANDLE hToken;
	if (OpenProcessToken(GetCurrentProcess(),
		TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY, &hToken))
	{
		LUID luid;
		if (LookupPrivilegeValue(NULL, szPrivilege, &luid))
		{
			BYTE t1[sizeof(TOKEN_PRIVILEGES) + sizeof(LUID_AND_ATTRIBUTES)];
			BYTE t2[sizeof(TOKEN_PRIVILEGES) + sizeof(LUID_AND_ATTRIBUTES)];
			DWORD cbTP = sizeof(TOKEN_PRIVILEGES) + sizeof(LUID_AND_ATTRIBUTES);

			PTOKEN_PRIVILEGES pTP = (PTOKEN_PRIVILEGES)t1;
			PTOKEN_PRIVILEGES pPrevTP = (PTOKEN_PRIVILEGES)t2;

			pTP->PrivilegeCount = 1;
			pTP->Privileges[0].Luid = luid;
			pTP->Privileges[0].Attributes = dwState;

			if (AdjustTokenPrivileges(hToken, FALSE, pTP, cbTP, pPrevTP, &cbTP))
				dwRtn = pPrevTP->Privileges[0].Attributes;
		}

		CloseHandle(hToken);
	}

	return dwRtn;
}


int _tmain(int argc, TCHAR* argv[])
{
	if (argc != 4)
	{
		usage();
		return 1;
	}

	// adjust privilege  
	_EnableNTPrivilege(SE_DEBUG_NAME, SE_PRIVILEGE_ENABLED);

	// InjectDll.exe <i|e> <PID> <dll_path>  
	if (!_tcsicmp(argv[1], L"i"))
	{
		InjectDll((DWORD)_tstoi(argv[2]), argv[3]);
	}
	else if (!_tcsicmp(argv[1], L"e"))
	{
		EjectDll((DWORD)_tstoi(argv[2]), argv[3]);
	}


	return 0;
}

DLL:

//hookiat.dll

#include "stdio.h"  
#include "wchar.h"  
#include "windows.h"  


// typedef  
typedef BOOL(WINAPI* PFSETWINDOWTEXTW)(HWND hWnd, LPWSTR lpString); //SetWindowsTextW()的地址


// 原函数地址
FARPROC g_pOrginalFunction = NULL;


BOOL WINAPI MySetWindowTextW(HWND hWnd, LPWSTR lpString)
{
	wchar_t* pNum = L"零一二三四五六七八九";
	wchar_t temp[2] = { 0, };
	int i = 0, nLen = 0, nIndex = 0;

	nLen = wcslen(lpString);
	for (i = 0; i < nLen; i++)
	{
		//   将阿拉伯数字转换为中文数字  
		//   lpString是宽字符版本(2个字节)字符串  
		if (L'0' <= lpString[i] && lpString[i] <= L'9')
		{
			temp[0] = lpString[i];
			nIndex = _wtoi(temp);
			lpString[i] = pNum[nIndex];
		}
	}

	//   调用原函数；user32.SetWindowTextW  
	//   (修改lpString缓冲区中的内容)  
	return ((PFSETWINDOWTEXTW)g_pOrginalFunction)(hWnd, lpString);
}

/**********************************/
//    函数名：hook_iat
//	  功能  ：负责实施IAT钩取的核心函数
/**********************************/
BOOL hook_iat(LPCSTR szDllName, PROC pfnOrg, PROC pfnNew)
{
	HMODULE hMod;
	LPCSTR szLibName;
	PIMAGE_IMPORT_DESCRIPTOR pImportDesc;
	PIMAGE_THUNK_DATA pThunk;
	DWORD dwOldProtect, dwRVA;
	PBYTE pAddr;

	// hMod, pAddr = ImageBase of calc.exe  
	//             = VA to MZ signature (IMAGE_DOS_HEADER)  
	hMod = GetModuleHandle(NULL);
	pAddr = (PBYTE)hMod;

	// pAddr = VA to PE signature (IMAGE_NT_HEADERS)  
	pAddr += *((DWORD*)&pAddr[0x3C]);

	// dwRVA = RVA to IMAGE_IMPORT_DESCRIPTOR Table  
	dwRVA = *((DWORD*)&pAddr[0x80]);

	// pImportDesc = VA to IMAGE_IMPORT_DESCRIPTOR Table  
	pImportDesc = (PIMAGE_IMPORT_DESCRIPTOR)((DWORD)hMod + dwRVA);

	for (; pImportDesc->Name; pImportDesc++)
	{
		// szLibName = VA to IMAGE_IMPORT_DESCRIPTOR.Name  
		szLibName = (LPCSTR)((DWORD)hMod + pImportDesc->Name);
		if (!_stricmp(szLibName, szDllName))
		{
			// pThunk = IMAGE_IMPORT_DESCRIPTOR.FirstThunk  
			//        = VA to IAT(Import Address Table)  
			pThunk = (PIMAGE_THUNK_DATA)((DWORD)hMod +
				pImportDesc->FirstThunk);

			// pThunk->u1.Function = VA to API  匹配成功
			for (; pThunk->u1.Function; pThunk++)
			{
				if (pThunk->u1.Function == (DWORD)pfnOrg)
				{
					// 更改为可读写模式  
					VirtualProtect((LPVOID)&pThunk->u1.Function,
						4,
						PAGE_EXECUTE_READWRITE,
						&dwOldProtect);

					// 修改IAT的值  
					pThunk->u1.Function = (DWORD)pfnNew;

					//修改完成后，恢复原保护属性
					VirtualProtect((LPVOID)&pThunk->u1.Function,
						4,
						dwOldProtect,
						&dwOldProtect);

					return TRUE;
				}
			}
		}
	}

	return FALSE;
}



BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
{
	switch (fdwReason)
	{
	case DLL_PROCESS_ATTACH:
		// 保存原始API的地址  
		g_pOrginalFunction = GetProcAddress(GetModuleHandle(L"user32.dll"),
			"SetWindowTextW");

		// # hook  
		//   用hookiat.MySetWindowText钩取user32.SetWindowTextW  
		hook_iat("user32.dll", g_pOrginalFunction, (PROC)MySetWindowTextW);
		break;

	case DLL_PROCESS_DETACH:
		// # unhook  
		//   将calc.exe的IAT恢复原值  
		hook_iat("user32.dll", (PROC)MySetWindowTextW, g_pOrginalFunction);
		break;
	}

	return TRUE;
}