void Hook()
{
DWORD dwOldProtect;
OldFuncAddr = (ULONG)MessageBoxA;
// MyFuncAddr = MyMessageBoxA的实际地址
//疑问一:(BYTE *)MyMessageBoxA+1 这个作何解释?
//疑问二: 为什么第二个参数是10呢?
VirtualProtect((LPVOID)jmp_backAddr, 10, PAGE_EXECUTE_READWRITE, &dwOldProtect);
MyFuncAddr = *(ULONG *)((BYTE *)MyMessageBoxA+1) + (ULONG)MyMessageBoxA + 5;
// jmp_backAddr = jmp_back的实际地址
jmp_backAddr = *(ULONG *)((BYTE *)jmp_back+1) + (ULONG)jmp_back + 5;
//修改内存为PAGE_EXECUTE_READWRITE
VirtualProtect((LPVOID)jmp_backAddr, 10, PAGE_EXECUTE_READWRITE, &dwOldProtect);
VirtualProtect((LPVOID)OldFuncAddr, 5, PAGE_EXECUTE_READWRITE, &dwOldProtect);
//计算跳转地址
*((ULONG*)(hook_code+1)) = (ULONG)MyFuncAddr - (ULONG)OldFuncAddr - 5;
memcpy(orig_code,(BYTE *)OldFuncAddr, 5);
memcpy((BYTE*)OldFuncAddr, hook_code, 5);
//计算返回地址
*((ULONG*)(jmp_org_code+1)) = (ULONG)OldFuncAddr - (ULONG)jmp_backAddr - 5;
memcpy((BYTE *)jmp_backAddr, orig_code, 5);
memcpy((BYTE *)jmp_backAddr + 5, jmp_org_code, 5);
}
__declspec(naked) int jmp_back()
{
__asm
{
_emit 0x90
_emit 0x90
_emit 0x90
_emit 0x90
_emit 0x90
_emit 0x90
_emit 0x90
_emit 0x90
_emit 0x90
_emit 0x90
}
}
//MyMessageBoxA:在函数执行前进行自己的处理
__declspec(naked) int MyMessageBoxA(
HWND hWnd, // handle to owner window
LPCTSTR lpText, // text in message box
LPCTSTR lpCaption, // message box title
UINT uType // message box style
)
{
printf("MyMessageBoxA is called\r\n");
__asm
{
pop head
pop hWnd
pop lpText
pop lpCaption
pop uType
}
MyFunc();////可以加入函数过程
__asm
{
//压栈过程
push uType
push lpCaption
push lpText
push hWnd
push head
//跳回MessageBoxA入口点
jmp jmp_back;
ret;
}
}
//MyMessageBoxA:在函数执行后进行自己的处理
__declspec(naked) int MyMessageBoxAA(
HWND hWnd, // handle to owner window
LPCTSTR lpText, // text in message box
LPCTSTR lpCaption, // message box title
UINT uType // message box style
)
{
printf("MyMessageBoxAA is called\r\n");
__asm
{
pop head
push offset s1;//返回地址为S1:
//跳回MessageBoxA入口点
jmp jmp_back;
s1: nop
}
MyFunc();
__asm
{
;//将原返回地址压栈
mov eax, 0;////演示:将返回结果改为0,也可由MyFunc返回
push head
ret;
}
}
int MyFunc()
{
printf("Hello World\r\n");
return 1;
}
//疑问一:(BYTE *)MyMessageBoxA+1 这个作何解释?
MyFuncAddr = *(ULONG *)((BYTE *)MyMessageBoxA+1) + (ULONG)MyMessageBoxA + 5;
//疑问二: 为什么第二个参数是10呢?
VirtualProtect((LPVOID)jmp_backAddr, 10, PAGE_EXECUTE_READWRITE, &dwOldProtect);
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