Trusted Locations: a source of misleading error messages

When's the last time you ran some VBA that opened a spreadsheet over the network? Or even on your own local temp folder?

If you're working in Office 2010 or 2013, you might just have seen this error message:

Office has detected a problem with this file. To help protect your computer this file cannot be opened.

...But you open the file yourself, manually, and it's fine. Readable, no error messages on open, maybe contains VBA macros and COM controls and you get a warning message, but not corrupted or obviously malicious.

You *might* see a message about content disabled, or the 'Trust Centre'.

What's actually happened is that the 'Trust Centre' ('Trust Center' in American English) needs a manual intervention to add the folder containing your file, and to label it as a safe location.

Microsoft have published instructions on doing this here:

Support.Office.com: Add, remove, or change a trusted location

That's great if it's just you, but unhelpful if you write applications that open Excel files. But, before I show you the VBA to automate away that annoyance, here's a short code snippet for opening Excel files safely in a separate 'sanitised' instance of Excel.exe:

Application.ShowStartupDialog = False

With New Excel.Application

    On Error Resume Next
    .ShowStartupDialog = False
    .Visible = False
    .EnableCancelKey = xlDisabled
    .UserControl = False
    .Interactive = False
    .EnableEvents = False
    'If .Calculation <> xlCalculationManual Then
    '    .Calculation = xlCalculationManual
    'End If
    '.CalculateBeforeSave = False
    .DisplayAlerts = False
    .AutomationSecurity = msoAutomationSecurityForceDisable
    
    On Error Resume Next
    For i = 1 To .AddIns.Count
        If .AddIns(i).IsOpen Then
            .AddIns(i).Installed = False
        End If
    Next i
    
    For i = 1 To .COMAddIns.Count
        .COMAddIns(i).Connect = False
        If Not .COMAddIns(i).Object Is Nothing Then
            .COMAddIns(i).Object.Close
            .COMAddIns(i).Object.Quit
        End If
    Next i    
      
    On Error GoTo ErrAppExit

    
    .Workbooks.Open FileName = strFile, _ 
                    UpdateLinks:=False,  _ 
                    ReadOnly:=True,  _ 
                    Password:=vbNullString,  _ 
                    Notify:=False,  _ 
                    AddToMRU:=False
  
  

    ' **** Your code to work on the file goes here **** 




    ' **** Set all objects to Nothing before exiting ****

  
    For i = .Workbooks.Count To 1 Step -1 
        .Workbooks(i).Close 
    Next i 
 
ErrAppExit:

    On Error Resume Next
    If Err.Number > 0 Then
        StatusMessage = "#ERROR " & Err.Number & ": " & Err.Description & sError
    End If
    
    .Quit
    
End With  'New Excel.Application 

The Trust Centre is annoying, but you might want to take *some* precautions when opening files from a bad neighborhood. Especially if others will use your VBA code to open files from places you never heard of.

Whatever. Here's the code to set a trusted location which I posted in StackOverflow a couple of days ago:

TrustThisFolder(): Excel VBA Code to Add a Folder to the 'Trusted Folders' Registry List.

Private Sub TrustThisFolder(Optional FolderPath As String, _
                            Optional TrustSubfolders As Boolean = True, _
                            Optional TrustNetworkFolders As Boolean = False, _
                            Optional sDescription As String)

' Add a folder to the 'Trusted Locations' list so that your project's VBA can
' open Excel files without raising errors like "Office has detected a problem
' with this file. To help protect your computer this file cannot be opened."

' Ths function has been implemented to fail silently on error: if you suspect
' that users don't have permission to assign 'Trusted Location' status in all
' locations, reformulate this as a function returning True or False

' Nigel Heffernan January 2015 http:\\Excellerando.blogspot.com
'
' Based on code published by Daniel Pineault in DevHut.net on June 23, 2010:
' www.devhut.net\2010\06\23\vbscript-createset-trusted-location-using-vbscript\

' **** **** **** ****  THIS CODE IS IN THE PUBLIC DOMAIN  **** **** **** ****

' UNIT TESTING:
'
' 1:    Reinstate the commented-out line 'Debug.Print sSubKey & vbTab & sPath
' 2:    Open the Immediate Window and run this command:
'           TrustThisFolder "Z:\", True, True, "The user's home directory"
' 3:    If  "Z:\"  is already in the list, choose another folder
' 4:    Repeat step 2 or 3: the folder should be listed in the debug output
' 5:    If it isn't listed, disable the error-handler and record any errors
'


On Error GoTo ErrSub


Dim sKeyPath    As String

Dim oRegistry   As Object
Dim sSubKey     As String
Dim oSubKeys    ' type not specified. After it's populated, it can be iterated
Dim oSubKey     ' type not specified.

Dim bSubFolders         As Boolean
Dim bNetworkLocation    As Boolean

Dim iTrustNetwork       As Long

Dim sPath   As String
Dim sDate   As String
Dim sDesc   As String
Dim i       As Long

Const HKEY_CURRENT_USER = &H80000001

bSubFolders = True
bNetworkLocation = False

If FolderPath = "" Then
    FolderPath = FSO.GetSpecialFolder(2).Path
    If sDescription = "" Then
        sDescription = "The user's local temp folder"
    End If
End If

If Right(FolderPath, 1) <> "\" Then
    FolderPath = FolderPath & "\"
End If



sKeyPath = ""
sKeyPath = sKeyPath & "SOFTWARE\Microsoft\Office\"
sKeyPath = sKeyPath & Application.Version
sKeyPath = sKeyPath & "\Excel\Security\Trusted Locations\"
 
 
 
Set oRegistry = GetObject("winmgmts:\\.\root\default:StdRegProv")
'   Note: not the usual \root\cimv2  for WMI scripting: the StdRegProv isn't in that folder
 
oRegistry.EnumKey HKEY_CURRENT_USER, sKeyPath, oSubKeys


For Each oSubKey In oSubKeys

    sSubKey = CStr(oSubKey)
    oRegistry.GetStringValue HKEY_CURRENT_USER, sKeyPath & "\" & sSubKey, "Path", sPath
    
    'Debug.Print sSubKey & vbTab & sPath
        
    If sPath = FolderPath Then
        Exit For
    End If
    

    
Next oSubKey

If sPath <> FolderPath Then

    If IsNumeric(Replace(sSubKey, "Location", "")) Then
        i = CLng(Replace(sSubKey, "Location", "")) + 1
    Else
        i = UBound(oSubKeys) + 1
    End If
    
    sSubKey = "Location" & CStr(i)
    
    If TrustNetworkFolders Then
        iTrustNetwork = 1
        oRegistry.GetDWORDValue HKEY_CURRENT_USER, sKeyPath, "AllowNetworkLocations", iTrustNetwork
        If iTrustNetwork = 0 Then
            oRegistry.SetDWORDValue HKEY_CURRENT_USER, sKeyPath, "AllowNetworkLocations", 1
        End If
    End If
    
    oRegistry.CreateKey HKEY_CURRENT_USER, sKeyPath & "\" & sSubKey
    oRegistry.SetStringValue HKEY_CURRENT_USER, sKeyPath & "\" & sSubKey, "Path", FolderPath
    oRegistry.SetStringValue HKEY_CURRENT_USER, sKeyPath & "\" & sSubKey, "Description", sDescription
    oRegistry.SetDWORDValue HKEY_CURRENT_USER, sKeyPath & "\" & sSubKey, "AllowSubFolders", 1
    
End If


ExitSub:

    Set oRegistry = Nothing
    Exit Sub

ErrSub:
    
    Resume ExitSub

End Sub

You will note that I acknowledge the original author, Daniel Pineault, who posted this code on DevHut.net in 2010: VB Script to set a Trusted Location

This code has been widely-reposted without attribution: please don't do that, it's discourteous - if you, too, aspire to being recognised as an 'expert', this can only happen if you're working in a culture that acknowledges expertise; and you, and your courtesy to others, *are* that culture.

Asterisk the Galling: Using The VBA InputBox() For Passwords

Using the VBA InputBox for passwords and hiding the user's keyboard input with asterisks.

This is another horrible hack, born from a requirement to stop storing Excel sheet and workbook passwords in the worksheets themselves, in the interests of security.

Experienced Excel developers, power users, IT security experts, and preserved rat brains floating in jars of formaldehyde might *just* be capable of reasoning-out one or two minor inconsistencies lurking in the logic of that statement.

However, I've still got to do it. And I can either create a VBA form and hope that the 'Password Chars' method exposed by some (but not all) textbox controls is reliable and secure, and can't be switched off by clever but misguided users; or just type the password into a standard VBA.Interaction InputBox() function.

Unfortunately, the InputBox function doesn't have a 'PasswordChars' option. So here's the simple and straightforward VBA code to do that, with the necessary API functions declared for both 64- and 32-bit environments:

Option Explicit


#If VBA7 And Win64 Then    ' 64 bit Excel under 64-bit windows   ' Use LongLong and LongPtr

    Private Declare PtrSafe Function FindWindowEx Lib "user32" Alias "FindWindowExA" _
                                    (ByVal hWnd1 As LongPtr, _
                                     ByVal hWnd2 As LongPtr, _
                                     ByVal lpsz1 As String, _
                                     ByVal lpsz2 As String _
                                     ) As LongPtr
    Private Declare PtrSafe Function FindWindow Lib "user32" Alias "FindWindowA" _
                                    (ByVal lpClassName As String, _
                                     ByVal lpWindowName As String) As LongPtr
    Private Declare PtrSafe Function SendMessage Lib "user32" Alias "SendMessageA" _
                                    (ByVal hwnd As LongPtr, _
                                     ByVal wMsg As Long, _
                                     ByVal wParam As Long, _
                                     ByRef lParam As Any _
                                     ) As LongPtr
    Private Declare PtrSafe Function SetTimer Lib "user32" _
                                    (ByVal hwnd As LongPtr, _
                                     ByVal nIDEvent As LongPtr, _
                                     ByVal uElapse As Long, _
                                     ByVal lpTimerFunc As LongPtr _
                                     ) As Long
     Public Declare PtrSafe Function KillTimer Lib "user32" _
                                    (ByVal hwnd As LongPtr, _
                                     ByVal nIDEvent As LongPtr _
                                     ) As Long
    
#ElseIf VBA7 Then     ' 64 bit Excel in all environments  ' Use LongPtr only, LongLong is not available

    Private Declare PtrSafe Function FindWindowEx Lib "user32" Alias "FindWindowExA" _
                                    (ByVal hWnd1 As LongPtr, _
                                     ByVal hWnd2 As LongPtr, _
                                     ByVal lpsz1 As String, _
                                     ByVal lpsz2 As String _
                                     ) As LongPtr
    Private Declare PtrSafe Function FindWindow Lib "user32" Alias "FindWindowA" _
                                    (ByVal lpClassName As String, _
                                     ByVal lpWindowName As String) As LongPtr
    Private Declare PtrSafe Function SendMessage Lib "user32" Alias "SendMessageA" _
                                    (ByVal hwnd As LongPtr, _
                                     ByVal wMsg As Long, _
                                     ByVal wParam As Long, _
                                     ByRef lParam As Any _
                                     ) As LongPtr
    Private Declare PtrSafe Function SetTimer Lib "user32" _
                                    (ByVal hwnd As LongPtr, _
                                     ByVal nIDEvent As Long, _
                                     ByVal uElapse As Long, _
                                     ByVal lpTimerFunc As LongPtr) As LongPtr
    Private Declare PtrSafe Function KillTimer Lib "user32" _
                                    (ByVal hwnd As LongPtr, _
                                     ByVal nIDEvent As Long) As Long

#Else    ' 32 bit Excel

    Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" _
                            (ByVal hWnd1 As Long, _
                             ByVal hWnd2 As Long, _
                             ByVal lpsz1 As String, _
                             ByVal lpsz2 As String _
                             ) As Long
    Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" _
                            (ByVal lpClassName As String, _
                             ByVal lpWindowName As String) As Long
    Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
                            (ByVal hwnd As Long, _
                             ByVal wMsg As Long, _
                             ByVal wParam As Long, _
                             ByRef lParam As Any _
                             ) As Long
    Private Declare Function SetTimer Lib "user32" _
                            (ByVal hwnd As Long, _
                             ByVal nIDEvent As Long, _
                             ByVal uElapse As Long, _
                             ByVal lpTimerFunc As Long) As Long
    Public Declare Function KillTimer Lib "user32" _
                            (ByVal hwnd As Long, _
                             ByVal nIDEvent As Long) As Long
#End If

Private Const PASSBOX_INPUT_CAPTION As String = "Password Required"
Private Const EM_SETPASSWORDCHAR    As Long = &HCC
Private Const NV_INPUTBOX           As Long = &H5000&




Public Function InputBoxPassword(Prompt As String, _
                                 Optional Default As String = vbNullString, _
                                 Optional XPos, Optional YPos, _
                                 Optional HelpFile, Optional HelpContext _
                                 ) As String
On Error Resume Next

' Replicates the functionality of a VBA InputBox function, with the user's
' typed input displayed as asterisks. The 'Title' parameter for the dialog
' caption is hardcoded as "Password Required" in this implementation.

' REQUIRED function: TimerProcInputBox
' REQUIRED API declarations: FindWindow, FindWindowEx, SetTimer, KillTimer


' Nigel Heffernan, January 2015, HTTP://Excellerando.Blogspot.com

' **** **** **** *** THIS CODE IS IN THE PUBLIC DOMAIN **** **** **** ****

' Based on code posted by user 'manish1239' in Xtreme Visual Basic Talk in
' October 2003 http://www.xtremevbtalk.com/archive/index.php/t-112708.html

' Coding notes: we send the 'Set PasswordChar' message to the textbox edit
' window in the VBA 'InputBox' dialog.  This isn't a straightforward task:
' InputBox is synchronous, a 'Modal Dialog' which leaves our application's
' VBA code in a waiting state at the exact moment we need to call the Send
' Message API function. So it runs by a delayed callback from an API Timer

' Warning: many of the 64-bit API declarations posted online are incorrect
' and *none* of them are correct for the pointer-safe Timer API Functions.



On Error Resume Next

SetTimer 0&, 0&, 10&, AddressOf TimerProcInputBox

InputBoxPassword = InputBox(Prompt, _
                            PASSBOX_INPUT_CAPTION, _
                            Default, _
                            XPos, YPos, _
                            HelpFile, HelpContext)


End Function



#If VBA7 And Win64 Then     ' 64 bit Excel under 64-bit windows  ' Use LongLong and LongPtr
                            ' Note that wMsg is always the WM_TIMER message, which fits in a Long
    Public Sub TimerProcInputBox(ByVal hwnd As LongPtr, _
                                 ByVal wMsg As Long, _
                                 ByVal idEvent As LongPtr, _
                                 ByVal dwTime As LongLong)
    On Error Resume Next
                         
    ' REQUIRED for Function InputBoxPassword
    ' https://msdn.microsoft.com/en-US/library/windows/desktop/ms644907(v=vs.85).aspx
    
    KillTimer hWndIbox, idEvent
    
    Dim hWndIbox As LongPtr   ' Handle to VBA InputBox
      
    hWndIbox = FindWindowEx(FindWindow("#32770", PASSBOX_INPUT_CAPTION), 0, "Edit", "")
    
    If hWndIbox <> 0 Then
        SendMessage hWndIbox, EM_SETPASSWORDCHAR, Asc("*"), 0&
    End If
        
    End Sub
    
#ElseIf VBA7 Then          ' 64 bit Excel in all environments   ' Use LongPtr only

    Public Sub TimerProcInputBox(ByVal hwnd As LongPtr, _
                                 ByVal wMsg As Long, _
                                 ByVal idEvent As LongPtr, _
                                 ByVal dwTime As Long)
    On Error Resume Next
                         
    ' REQUIRED for Function InputBoxPassword
    ' https://msdn.microsoft.com/en-US/library/windows/desktop/ms644907(v=vs.85).aspx
    
    Dim hWndIbox As LongPtr    ' Handle to VBA InputBox
    
    KillTimer hwnd, idEvent
    
    hWndIbox = FindWindowEx(FindWindow("#32770", PASSBOX_INPUT_CAPTION), 0, "Edit", "")
     
    
    If hWndIbox <> 0 Then
        SendMessage hWndIbox, EM_SETPASSWORDCHAR, Asc("*"), 0&
    End If
        
        
    End Sub
    
#Else    ' 32 bit Excel

    Public Sub TimerProcInputBox(ByVal hwnd As Long, _
                                 ByVal wMsg As Long, _
                                 ByVal idEvent As Long, _
                                 ByVal dwTime As Long)
    On Error Resume Next
    
    ' REQUIRED for Function InputBoxPassword
    ' https://msdn.microsoft.com/en-US/library/windows/desktop/ms644907(v=vs.85).aspx
    
    Dim hWndIbox As Long    ' Handle to VBA InputBox
    
    KillTimer hwnd, idEvent
      
    hWndIbox = FindWindowEx(FindWindow("#32770", PASSBOX_INPUT_CAPTION), 0&, "Edit", "")
    
    If hWndIbox <> 0 Then
        SendMessage hWndIbox, EM_SETPASSWORDCHAR, Asc("*"), 0&
    End If
        
        
    End Sub

#End If

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