Disable Macros programmatically @ runtime

Jaafar Tribak

Well-known Member
Joined
Dec 5, 2002
Messages
8,253
Office Version
  1. 2016
Platform
  1. Windows
I stumbled on an oddity while experimenting with lightweight objects in vba that I thought maybe would be worthwhile sharing .. Not of much use but, interesting nevertheless.

I discovered by accident that when a runtime error occurs while there is a lightweight object in memory, Macros get completly disabled !... and that includes events, UDFs etc...

So I thought I would turn this "side effect' into my advantage and allow it to disable macros programmatically at runtime.

One issue with this is that it disables macros at the application level scope so all other macro enabled workbooks that happen to be open in the current application instance also get affected.

Tested on Excel 2010 - Win 10 .. Not sure if this will work in other systems.

Here is the code in a Standard Module: (run the DisabelMacros routine)
Code:
Option Explicit

[URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=If]#If[/URL]  VBA7 Then

    Private hHook As LongPtr
    
    Private Declare PtrSafe Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As LongPtr)
    Private Declare PtrSafe Function GetClassName Lib "user32" Alias "GetClassNameA" (ByVal hwnd As LongPtr, ByVal lpClassName As String, ByVal nMaxCount As Long) As Long
    Private Declare PtrSafe Function GetWindowText Lib "user32" Alias "GetWindowTextA" (ByVal hwnd As LongPtr, ByVal lpString As String, ByVal cch As Long) As Long
    Private Declare PtrSafe Function GetDlgItem Lib "user32" (ByVal hDlg As LongPtr, ByVal nIDDlgItem As Long) As LongPtr
    Private Declare PtrSafe Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As LongPtr, ByVal wMsg As Long, ByVal wParam As LongPtr, lParam As Any) As LongPtr
    Private Declare PtrSafe Function SetWindowsHookEx Lib "user32" Alias "SetWindowsHookExA" (ByVal idHook As Long, ByVal lpfn As LongPtr, ByVal hmod As LongPtr, ByVal dwThreadId As Long) As LongPtr
    Private Declare PtrSafe Function UnhookWindowsHookEx Lib "user32" (ByVal hHk As LongPtr) As Long
    Private Declare PtrSafe Function CallNextHookEx Lib "user32" (ByVal hHook As LongPtr, ByVal ncode As Long, ByVal wParam As LongPtr, lParam As Any) As LongPtr
    Private Declare PtrSafe Function GetCurrentThreadId Lib "kernel32" () As Long

[URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=Else]#Else[/URL] 

    Private hHook As Long
    
    Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal Length As Long)
    Private Declare Function GetClassName Lib "user32" Alias "GetClassNameA" (ByVal hwnd As Long, ByVal lpClassName As String, ByVal nMaxCount As Long) As Long
    Private Declare Function GetWindowText Lib "user32" Alias "GetWindowTextA" (ByVal hwnd As Long, ByVal lpString As String, ByVal cch As Long) As Long
    Private Declare Function GetDlgItem Lib "user32" (ByVal hDlg As Long, ByVal nIDDlgItem As Long) As Long
    Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
    Private Declare Function SetWindowsHookEx Lib "user32" Alias "SetWindowsHookExA" (ByVal idHook As Long, ByVal lpfn As Long, ByVal hmod As Long, ByVal dwThreadId As Long) As Long
    Private Declare Function UnhookWindowsHookEx Lib "user32" (ByVal hhk As Long) As Long
    Private Declare Function CallNextHookEx Lib "user32" (ByVal hHook As Long, ByVal ncode As Long, ByVal wParam As Long, lParam As Any) As Long
    Private Declare Function GetCurrentThreadId Lib "kernel32" () As Long

[URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=End]#End[/URL]  If
    
Private Const WH_CBT = 5
Private Const HCBT_ACTIVATE As Long = 5
Private Const BM_CLICK = &HF5

Private unk As IUnknown


Sub DisabelMacros()

    [URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=If]#If[/URL]  VBA7 Then
        Dim unkVtable(0 To 2) As LongPtr, pVtable As LongPtr
        unkVtable(2) = VBA.CLngPtr(AddressOf Release)
    [URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=Else]#Else[/URL] 
        Dim unkVtable(0 To 2) As Long, pVtable As Long
        unkVtable(2) = VBA.CLng(AddressOf Release)
    [URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=End]#End[/URL]  If

    pVtable = VarPtr(unkVtable(0))
    CopyMemory unk, VarPtr(pVtable), LenB(pVtable)
    hHook = SetWindowsHookEx(WH_CBT, AddressOf HookProc, 0, GetCurrentThreadId)
    MsgBox "Macros have been Disabled.", vbInformation
    Err.Raise 11
End Sub


Private Function Release() As Long

End Function


[URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=If]#If[/URL]  VBA7 Then
    Private Function HookProc(ByVal idHook As Long, ByVal wParam As LongPtr, ByVal lParam As LongPtr) As LongPtr
[URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=Else]#Else[/URL] 
    Private Function HookProc(ByVal idHook As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
[URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=End]#End[/URL]  If

    Dim sBuffer As String * 256, lRet As Long
    
    If idHook = HCBT_ACTIVATE Then
        lRet = GetClassName(wParam, sBuffer, 256)
        If Left(sBuffer, lRet) = "#32770" Then
            lRet = GetWindowText(wParam, sBuffer, 256)
            If Left(sBuffer, lRet) = "Microsoft Visual Basic" Then
                Call SendMessage(GetDlgItem(wParam, &H12C0), BM_CLICK, 0, 0)
                UnhookWindowsHookEx hHook
            End If
        End If
    End If
    
    HookProc = CallNextHookEx(hHook, idHook, ByVal wParam, ByVal lParam)
End Function
 

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