Option Explicit
Private Const PAGE_EXECUTE_READWRITE = &H40
 
Private Declare PtrSafe Sub MoveMemory Lib "kernel32" Alias "RtlMoveMemory" _
(Destination As LongPtr, Source As LongPtr, ByVal Length As LongPtr)
 
Private Declare PtrSafe Function VirtualProtect Lib "kernel32" (lpAddress As LongPtr, _
ByVal dwSize As LongPtr, ByVal flNewProtect As LongPtr, lpflOldProtect As LongPtr) As LongPtr
 
Private Declare PtrSafe Function GetModuleHandleA Lib "kernel32" (ByVal lpModuleName As String) As LongPtr
 
Private Declare PtrSafe Function GetProcAddress Lib "kernel32" (ByVal hModule As LongPtr, _
ByVal lpProcName As String) As LongPtr
 
Private Declare PtrSafe Function DialogBoxParam Lib "user32" Alias "DialogBoxParamA" (ByVal hInstance As LongPtr, _
ByVal pTemplateName As LongPtr, ByVal hWndParent As LongPtr, _
ByVal lpDialogFunc As LongPtr, ByVal dwInitParam As LongPtr) As Integer
 
Dim HookBytes(0 To 11) As Byte
Dim OriginBytes(0 To 11) As Byte
Dim pFunc As LongPtr
Dim Flag As Boolean
 
Private Function GetPtr(ByVal Value As LongPtr) As LongPtr      '获得函数的地址
    GetPtr = Value
End Function
 
Public Sub RecoverBytes()   '若已经hook,则恢复原API开头的6字节,也就是恢复原来函数的功能
    If Flag Then MoveMemory ByVal pFunc, ByVal VarPtr(OriginBytes(0)), 12
End Sub
 
Public Function Hook() As Boolean
    Dim TmpBytes(0 To 11) As Byte
    Dim p As LongPtr, osi As Byte
    Dim OriginProtect As LongPtr
 
    Hook = False
    'VBE6.dll调用DialogBoxParamA显示VB6INTL.dll资源中的第4070号对话框(就是输入密码的窗口)
    '若DialogBoxParamA返回值非0,则VBE会认为密码正确,所以我们要hook DialogBoxParamA函数
    #If Win64 Then
        osi = 1
    #Else
        osi = 0
    #End If
 
    pFunc = GetProcAddress(GetModuleHandleA("user32.dll"), "DialogBoxParamA")
    '标准api hook过程之一: 修改内存属性,使其可写
    If VirtualProtect(ByVal pFunc, 12, PAGE_EXECUTE_READWRITE, OriginProtect) <> 0 Then
        '标准api hook过程之二: 判断是否已经hook,看看API的第一个字节是否为&H68,
        '若是则说明已经Hook
        MoveMemory ByVal VarPtr(TmpBytes(0)), ByVal pFunc, osi + 1
        If TmpBytes(osi) <> &HB8 Then
            '标准api hook过程之三: 保存原函数开头字节,这里是6个字节,以备后面恢复
            MoveMemory ByVal VarPtr(OriginBytes(0)), ByVal pFunc, 12
            '用AddressOf获取MyDialogBoxParam的地址
            '因为语法不允许写成p = AddressOf MyDialogBoxParam,这里我们写一个函数
            'GetPtr,作用仅仅是返回AddressOf MyDialogBoxParam的值,从而实现将
            'MyDialogBoxParam的地址付给p的目的
            p = GetPtr(AddressOf MyDialogBoxParam)
            '标准api hook过程之四: 组装API入口的新代码
            'HookBytes 组成如下汇编
            'push MyDialogBoxParam的地址
            'ret
            '作用是跳转到MyDialogBoxParam函数
            If osi Then HookBytes(0) = &H48
            HookBytes(osi) = &HB8
            osi = osi + 1
            MoveMemory ByVal VarPtr(HookBytes(osi)), ByVal VarPtr(p), 4 * osi
            HookBytes(osi + 4 * osi) = &HFF
            HookBytes(osi + 4 * osi + 1) = &HE0
            '标准api hook过程之五: 用HookBytes的内容改写API前6个字节
            MoveMemory ByVal pFunc, ByVal VarPtr(HookBytes(0)), 12
            '设置hook成功标志
            Flag = True
            Hook = True
        End If
    End If
End Function
 
Private Function MyDialogBoxParam(ByVal hInstance As LongPtr, _
ByVal pTemplateName As LongPtr, ByVal hWndParent As LongPtr, _
ByVal lpDialogFunc As LongPtr, ByVal dwInitParam As LongPtr) As Integer
 
    If pTemplateName = 4070 Then
        '有程序调用DialogBoxParamA装入4070号对话框,这里我们直接返回1,让VBE以为密码正确了
        MyDialogBoxParam = 1
    Else         '有程序调用DialogBoxParamA,但装入的不是4070号对话框,这里我们调用RecoverBytes函数恢复原来函数的功能,在进行原来的函数
        RecoverBytes
        MyDialogBoxParam = DialogBoxParam(hInstance, pTemplateName, _
                   hWndParent, lpDialogFunc, dwInitParam)
        Hook        '原来的函数执行完毕,再次hook
    End If
End Function