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http://www.programfan.com/article/showarticle.asp?id=2786
其中Dll文件為：
HHOOK g_hHook;
HINSTANCE g_hinstDll;
FARPROC pfMessageBoxA;
int WINAPI MyMessageBoxA(HWND hWnd, LPCTSTR lpText,LPCTSTR lpCaption,UINT uType);
BYTE OldMessageBoxACode[5],NewMessageBoxACode[5];
HMODULE hModule ;
DWORD dwIdOld,dwIdNew;
BOOL bHook=false;
void HookOn();
void HookOff();
BOOL init();
LRESULT WINAPI MousHook(int nCode,WPARAM wParam,LPARAM lParam);
BOOL APIENTRY DllMain( HANDLE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
switch (ul_reason_for_call)
{
case DLL_PROCESS_ATTACH:
if(!init())
{
MessageBoxA(NULL,"Init","ERROR",MB_OK);
return(false);
}
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
case DLL_PROCESS_DETACH:
if(bHook) UnintallHook();
break;
}
return TRUE;
}
LRESULT WINAPI Hook(int nCode,WPARAM wParam,LPARAM lParam)//空的鉤子函數
{
return(CallNextHookEx(g_hHook,nCode,wParam,lParam));
}
HOOKAPI2_API BOOL InstallHook()//輸出安裝空的鉤子函數
{
g_hinstDll=LoadLibrary("HookApi2.dll");
g_hHook=SetWindowsHookEx(WH_GETMESSAGE,(HOOKPROC)Hook,g_hinstDll,0);
if (!g_hHook)
{
MessageBoxA(NULL,"SET ERROR","ERROR",MB_OK);
return(false);
}
return(true);
}
HOOKAPI2_API BOOL UninstallHook()//輸出御在鉤子函數
{
return(UnhookWindowsHookEx(g_hHook));
}
BOOL init()//初始化得到MessageBoxA的地址，并生成Jmp XXX(MyMessageBoxA)的跳轉指令
{
hModule=LoadLibrary("user32.dll");
pfMessageBoxA=GetProcAddress(hModule,"MessageBoxA");
if(pfMessageBoxA==NULL)
return false;
_asm
{
lea edi,OldMessageBoxACode
mov esi,pfMessageBoxA
cld
movsd
movsb
}
NewMessageBoxACode[0]=0xe9;//jmp MyMessageBoxA的相對地址的指令
_asm
{
lea eax,MyMessageBoxA
mov ebx,pfMessageBoxA
sub eax,ebx
sub eax,5
mov dword ptr [NewMessageBoxACode+1],eax
}
dwIdNew=GetCurrentProcessId(); //得到所屬進程的ID
dwIdOld=dwIdNew;
HookOn();//開始攔截
return(true);
}
int WINAPI MyMessageBoxA(HWND hWnd, LPCTSTR lpText,LPCTSTR lpCaption, UINT uType )//首先關閉攔截，然后才能調用被攔截的Api 函數
{
int nReturn=0;
HookOff();
nReturn=MessageBoxA(hWnd,"Hook",lpCaption,uType);
HookOn();
return(nReturn);
}
void HookOn()
{
HANDLE hProc;
dwIdOld=dwIdNew;
hProc=OpenProcess(PROCESS_ALL_ACCESS,0,dwIdOld);//得到所屬進程的句柄
VirtualProtectEx(hProc,pfMessageBoxA,5,PAGE_READWRITE,&dwIdOld);
//修改所屬進程中MessageBoxA的前5個字節的屬性為可寫
WriteProcessMemory(hProc,pfMessageBoxA,NewMessageBoxACode,5,0);
//將所屬進程中MessageBoxA的前5個字節改為JMP 到MyMessageBoxA
VirtualProtectEx(hProc,pfMessageBoxA,5,dwIdOld,&dwIdOld);
//修改所屬進程中MessageBoxA的前5個字節的屬性為原來的屬性
bHook=true;
}
void HookOff()//將所屬進程中JMP MyMessageBoxA的代碼改為Jmp MessageBoxA
{
HANDLE hProc;
dwIdOld=dwIdNew;
hProc=OpenProcess(PROCESS_ALL_ACCESS,0,dwIdOld);
VirtualProtectEx(hProc,pfMessageBoxA,5,PAGE_READWRITE,&dwIdOld);
WriteProcessMemory(hProc,pfMessageBoxA,OldMessageBoxACode,5,0);
VirtualProtectEx(hProc,pfMessageBoxA,5,dwIdOld,&dwIdOld);
bHook=false;
}
//測試文件：
int APIENTRY WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
if(!InstallHook())
{
MessageBoxA(NULL,"Hook Error!","Hook",MB_OK);
return 1;
}
MessageBoxA(NULL,"TEST","TEST",MB_OK);//可以看見Test變成了Hook,也可以在其他進程中看見
if(!UninstallHook())
{
MessageBoxA(NULL,"Uninstall Error!","Hook",MB_OK);
return 1;
}
return 0;
}
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