[Tutorial] "DLL injection and DLL injection example" (1/2)

DLL Injection is a technique used for running code within the address space of another process by forcing it to load a "dynamic link library injection".

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DLL injection is often used by external programs to influence the behavior of another program in a way its authors did not anticipate or intend

A program used to inject arbitrary code into arbitrary processes is called a DLL injector
Using SetWindowHookEx API for DLL injection
 

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Remarks:

            SetWindowsHookEx can be used to inject a DLL into another process. A 32-bit DLL cannot be injected into a 64-bit process, and a 64-bit DLL cannot be injected into a 32-bit process. If an application requires the use of hooks in other processes, it is required that a 32-bit application call SetWindowsHookEx to inject a 32-bit DLL into 32-bit processes, and a 64-bit application call SetWindowsHookEx to inject a 64-bit DLL into 64-bit processes. The 32-bit and 64-bit DLLs must have different names.

          Because hooks run in the context of an application, they must match the "bitness" of the application. If a 32-bit application installs a global hook on 64-bit Windows, the 32-bit hook is injected into each 32-bit process (the usual security boundaries apply). In a 64-bit process, the threads are still marked as "hooked." However, because a 32-bit application must run the hook code, the system executes the hook in the hooking app's context; specifically, on the thread that called SetWindowsHookEx. This means that the hooking application must continue to pump messages or it might block the normal functioning of the 64-bit processes.

            If a 64-bit application installs a global hook on 64-bit Windows, the 64-bit hook is injected into each 64-bit process, while all 32-bit processes use a callback to the hooking application.
To hook all applications on the desktop of a 64-bit Windows installation, install a 32-bit global hook and a 64-bit global hook, each from appropriate processes, and be sure to keep pumping messages in the hooking application to avoid blocking normal functioning. If you already have a 32-bit global hooking application and it doesn't need to run in each application's context, you may not need to create a 64-bit version.
Here is my code show you how to Inject DLL To Any Process
You can download my projects from here

Demo here:

Create My dll same here

  // dllmain.cpp : Defines the entry point for the DLL application.
  /* ****************************************
   * Author: Zidane (huuvi168@gmail.com)
   * Last modified: 2015-06-08
   * ****************************************/
  #include "stdafx.h"
  #include "dll.h"
  
  #define PARAM_ONE 1000
  
  const UINT WM_HOOK_WRITE = RegisterWindowMessage(L"WM_HOOK_WRITE");
  const UINT WM_HOOKEX = RegisterWindowMessage(L"WM_HOOKEX_RK");
  
  #define pCW ((CWPSTRUCT*)lParam)
  
  WNDPROC OldWndProc = NULL;
  LRESULT CALLBACK NewWndProc(HWND,UINT,WPARAM,LPARAM);
  BOOL bHooked = 0;
  HWND ghWnd;
  
  HHOOK hHookKeyBoard;
  HINSTANCE hModuleDll;
  
  
  BOOL APIENTRY DllMain( HMODULE hModule,
                         DWORD  ul_reason_for_call,
                         LPVOID lpReserved
                      )
  {
      switch (ul_reason_for_call)
      {
          case DLL_PROCESS_ATTACH:
               hModuleDll = (HINSTANCE) hModule;
               DisableThreadLibraryCalls(hModuleDll); 
    
               break;
          case DLL_THREAD_ATTACH:
          case DLL_THREAD_DETACH:
          case DLL_PROCESS_DETACH:
               break;
      }
      return TRUE;
  
  }
  
  
  // hàm HookPro phải có CALLBACK, không có CALLBACK sẽ bị lỗi not response
  LRESULT CALLBACK HookProc (int nCode, WPARAM wParam, LPARAM lParam)
  {
      HHOOK hHook = (HHOOK)pCW->wParam;
  
      if(nCode<0)
          return CallNextHookEx(hHook, nCode, wParam,lParam);
  
      HWND hVLWnd = pCW->hwnd;
   
      if((pCW->message == WM_HOOKEX) && pCW->lParam)
      {
          UnhookWindowsHookEx(hHookKeyBoard);
          if (bHooked)
              return CallNextHookEx(hHook, nCode, wParam,lParam);
        
          TCHAR lib_name[MAX_PATH];
          GetModuleFileName(hModuleDll, lib_name, MAX_PATH);
          if(!LoadLibrary(lib_name))
              return CallNextHookEx(hHook, nCode, wParam,lParam);
          OldWndProc = (WNDPROC)SetWindowLong(hVLWnd, GWL_WNDPROC, (LONG)NewWndProc);
    
          if(OldWndProc == NULL) {
               FreeLibrary(hModuleDll);
          }
          else
          {
              bHooked = TRUE;
          }
      }
      else if(pCW->message == WM_HOOKEX) 
      {
          UnhookWindowsHookEx(hHookKeyBoard);
          if (!bHooked)
              return CallNextHookEx(hHook, nCode, wParam,lParam);
          if(!SetWindowLong(hVLWnd, GWL_WNDPROC, (LONG)OldWndProc))
              return CallNextHookEx(hHook, nCode, wParam,lParam);
          FreeLibrary(hModuleDll);
          bHooked = FALSE;
      } 
  }
  
  LRESULT CALLBACK NewWndProc(HWND hWnd, UINT uMsg, 
                              WPARAM wParam, LPARAM lParam)
  {  
      if (uMsg == WM_HOOK_WRITE)
      { 
   
          switch (wParam) // Received from Application Demo
          {   
              case PARAM_ONE:
                   MessageBox(hWnd, L"received message 
                      succeed from dll!",L"learn-tech-tips",0);
                   break;
           }
       }
       return CallWindowProc(OldWndProc, hWnd, uMsg, wParam, lParam);
  }
  
  int InjectDll(HWND hWnd)
  {  
      if (!IsWindow(hWnd))
           return 0;
      ghWnd = hWnd;
   
      hHookKeyBoard = SetWindowsHookEx(WH_CALLWNDPROC, HookProc, hModuleDll,  
                                       GetWindowThreadProcessId(hWnd,NULL));
   
      MessageBox(hWnd, L"InjectDll succeed!",L"learn-tech-tips",0);
      if(hHookKeyBoard == NULL)
      {
          return 0;
      }
      else
      {
          SendMessage(hWnd, WM_HOOKEX, WPARAM(hHookKeyBoard), 1);
  
      }
      return 1;
  }
  
  int UnmapDll(HWND hWnd)
  { 
      if (!IsWindow(hWnd))
          return 0;
      HHOOK hHook = SetWindowsHookEx(WH_CALLWNDPROC,
                  (HOOKPROC)HookProc, hModuleDll, 
              GetWindowThreadProcessId(hWnd,NULL));
     
      if(hHook==NULL)
          return 0;
      SendMessage(hWnd, WM_HOOKEX, (WPARAM)hHook, 0);
      return 1;
  }
  

  // dll.h
  /* ****************************************
   * Author: Zidane (huuvi168@gmail.com)
   * Last modified: 2015-06-08
   * ****************************************/
  #if _MSC_VER > 1000
  #pragmaonce
  #endif
  
  #if !defined INJECT_EX__H
  #define INJECT_EX__H
  
  #ifdef INJECT_EX_EXPORTS
  #define HOOKDLL_API extern "C" __declspec(dllexport)
  #else
  #define HOOKDLL_API extern"C"__declspec(dllimport)
  #endif
  
  HOOKDLL_API int InjectDll(HWND hWnd);
  HOOKDLL_API int UnmapDll(HWND hWnd);
  
  #endif
  

Now create new project with application
Add -> Reference

/* ****************************************
   * Author: Zidane (huuvi168@gmail.com)
   * Last modified: 2015-06-08
   * ****************************************/
  
  void CAppDlg::OnBnClickedButtonSendmsg()
  {
      // TODO: Add your control notification handler code here 
    
      CString sWindowName = L"Hex";
      m_hVLWin = ::FindWindow(NULL, sWindowName);
  
      if (!m_hVLWin)
          return;
   
      if (InjectDll(m_hVLWin))
          SetWindowTextW(L"Inject " + sWindowName + L" Succeed! 
                                          Ready to call function ...");
  }
  
  void CAppDlg::OnBnClickedButtonExec()
  {
      // TODO: Add your control notification handler code here
      ::SendMessage(m_hVLWin, WM_HOOK_WRITE, PARAM_ONE, 1 );
  }
  

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