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Active Directory authentication/group membership check with MSAccess 2007 VBA

I'm unfortunately responsible for maintaining some old interfaces written in VBA through MS Access. Currently I'm migrating these over to a new server and one of the things I want to do is improve the login system for these interfaces by integrating them with Active Directory. It's pretty simple: All I need to do is (a) check to make sure the provided username/password combination are correct, and if so, (b) check to see if the user is in a specific Active Directory group.

Any ideas on how to go about doing this? I had written a library in .NET that these interfaces were using on the old server, but on the new server it's not working properly. If there's some way that I can pretty easily and effectively do it right through VBA, I'd prefer that over having to troubleshoot this library that I wrote.

EDIT: I should add, I've been playing around with ADODB to make the connection. It seems to work and I can look up AD object properties but I'm not sure what the best way is to check the username/password.

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Neil Russell

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datAdrenaline

In addition ... if you wish to protect your data, then place your data in a Shared Folder, then assign an Active Directory group full permissions in to the folder. All your Front Ends should be local (or private) to the user who has access to the back end.

Also, as an alternative to Neilsr's suggestion, here is what I use to determine the groups the current logged in user is in. It returns a pipe delimited list of groups the user is in for the passed domain.

Public Function GroupsForCurrentUser(strDomain As String) As String

    Dim sADsPath As String, sGroupName As String _
        , sDescription As String, sUsersGroupList As String
    Dim oTarget As Object
    Dim vGroup As Variant
    Dim wshNetwork As Object
    
    Set wshNetwork = CreateObject("wscript.network")
    
    ' Bind to Computer object
    Set oTarget = GetObject("WinNT://" & strDomain & "/" & wshNetwork.UserName & ",user")
    
    For Each vGroup In oTarget.Groups
        sUsersGroupList = sUsersGroupList & "|" & vGroup.Name
    Next
    
    sUsersGroupList = UCase(sUsersGroupList)
    
    GroupsForCurrentUser = sUsersGroupList & "|"
    
End Function

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I will use the function like this ...

If GroupsForCurrentUser("someDomain") Like "*|someGroupName|*"  Then ....

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elorc

ASKER

Thanks for the replies. For security and auditing purposes, these interfaces are required to authenticate the user again when they are launched before access can be granted. We are not allowed to assume that the user is authenticated because they are logged into Windows already.

datAdrenaline

>> We are not allowed to assume that the user is authenticated because they are logged into Windows already. <<

Do you mean authenticated to use your app? or .. Are you not allowed to assume the logged in user is the one in front of the computer?

elorc

ASKER

Whenever they load the interface, it has to prompt them for the password. The assumption is that just because they are logged into Windows does not mean they're the person currently at the keyboard, so the interface must require login credentials every time it's opened.

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datAdrenaline

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elorc

ASKER

That seems to work. What a cluser though. :)

I've been working on rewriting these crappy interfaces as actual .NET applications, but it's pretty time consuming so it's taking me a while to get them all done. This will keep the ones I haven't gotten to yet limping along for the time being. Thank you.

Neil Russell

Nice find! :D

Can I suguest you use the first part to find the current logged on username and just prompt for the password? Avoid a user running the app in another users windows session? I know i would find that insecure somewhere along the line if your concerns are what they are.

Regards

datAdrenaline

Yes it is a cluster! ... so I kept digging -- it was really bothering me! .. and this is what I came up with. It works for me on my PC in VBA, but I am an administrator, so I don't know if permissions will be an issue.

Public Function ValidateUser(strDomain As String, strUserName As String, strPassword As String) As Boolean
    
    Dim oADobject As Object 'IADsOpenDSObject
    Set oADobject = GetObject("WinNT:")
    
    On Error Resume Next
    oADobject.OpenDSObject "WinNT://" & strDomain, strUserName, strPassword, &O1 'ADS_SECURE_AUTHENTICATION)
    
    ValidateUser = (Err = 0)
    Err.Clear
       
End Function

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By the way, it seems the code I first linked you to was born out of this MS article ...

http://support.microsoft.com/default.aspx?scid=kb;en-us;279815

elorc

ASKER

That second code you provided works under normal users as well. When the login credentials are incorrect it looks like it can sometimes take several seconds to return false, but that's fine. I like the simplicity of that solution.

datAdrenaline

Cool! ..

In my testing, I did notice the delay when an error was thrown also. But, like you, I prefer the simplicity and will take the hit of the small delay versus the hit of a module with code that I would rather not touch!

Either way you go, I am glad the information found helped you out! I learned some stuff too, so it was a double bonus!

Good luck on your project(s)!

elorc

ASKER

I'll just explain to users that the small delay is "an intentional implementation designed to reduce the effectiveness of brute force attacks."

8)

Thanks again for the assistance that you both provided. I was able to put it all together to do exactly what I was looking for.