VBScript / ASP Secure LDAP Query of User Group Membership

Check if a user is a member of a specified domain security group using a secure LDAP query with ADsDSoObject provider. Works for ASP and VBScript using a specified domain service/proxy user account (when anonymous LDAP is disabled).

Example:
If IsMemberOf("SalesManagers", "JohnDoe") Then
    Response.Write "is a member"
End If

Const ldap_user = "domain\useraccount"
Const ldap_pwd  = "P@ssW0rd$"
Const ou = "OU=Sales,OU=North America,OU=Corp,DC=contoso,DC=com"
Const ADS_SCOPE_SUBTREE = 2

Function IsMemberOf(groupName, uid)
    Dim objConnection, objCommand, objRecordSet
    Dim retval : retval = False
    Dim i, gplen : gplen = Len(groupName)+3
 
    On Error Resume Next
    Set objConnection = CreateObject("ADODB.Connection")
    Set objCommand =   CreateObject("ADODB.Command")
 
    objConnection.Provider = "ADsDSOObject"
    objConnection.Properties("User ID")  = ldap_user
    objConnection.Properties("Password") = ldap_pwd
    objConnection.Properties("Encrypt Password") = TRUE
    objConnection.Properties("ADSI Flag") = 1
    objConnection.Open "Active Directory Provider"

    Set objCommand.ActiveConnection = objConnection

    objCommand.Properties("Page Size") = 1000
    objCommand.Properties("Searchscope") = ADS_SCOPE_SUBTREE
    objCommand.CommandText = "SELECT memberof FROM 'LDAP://" & ou & "' " & _
        "WHERE objectCategory='user' AND sAMAccountName='" & uid & "'"

    Set objRecordSet = objCommand.Execute

    objRecordSet.MoveFirst
    Do Until objRecordSet.EOF
        For i = 0 to objRecordSet.Fields.Count -1
            For each m in objRecordSet.Fields("memberof").value
                If Left(Ucase(m),gplen) = Ucase("CN=" & groupname) Then
                    retval = True
                End If
            Next
        Next
        objRecordSet.MoveNext
    Loop
    objRecordSet.Close
    Set objRecordSet = Nothing
    Set objCommand = Nothing
    Set objConnection = Nothing
    IsMemberOf = retval
End Function