Tag Archives: GPP

Friendly Reminder – do NOT assign passwords through Group Policy Preferences

This is an issue that have been out for quite a while, but I see it a lot when checking customers environments, so it’s always good to remind yourself about this kind of important things.

Through GPP, you have the ability to do lots of stuff, one of them is fiddling with builtin local accounts on computers and even change password on those.

A common case is applying GPP settings as below to your client computers.
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Note the warning about where the password will be stored.

It actually gets worse from there… with the script which can be downloaded here, you can extract ALL passwords from ALL GPP’s you have since they are stored in XML files located on the sysvol in your domain.
OK, who have access to read those files then?
Authenticated Users, which means whoever that has an account in your domain can do this.
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Conclusion: do not change password with GPP unless you do it and remove the policy directly after the policy has successfully been applied.

In this blog post series from Microsoft PFE’s, you find a great solution to handle and store local admin passwords in a secure, yet manageble way.



Getting all GPP Drive maps in a Domain with PowerShell

Group Policy Preferences are mostly great and frequently used to solve different kind of policy related problems in an it Environment.
There are a few PowerShell cmdlet for GPO’s (28 last time I checked) but only three of them are related to Group Policy Preferences.
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Case and Solution
A customer of mine wanted to inventory their GPP Drive maps, and get information about what GPO, drive letter, drivepath, security Filtering and so on.

I know there are quite a few solutions that can do this for you, but why not use PowerShell when possible? 🙂

The script is using the GroupPolicy POSH-module which has been around since 2008R2, so this works even there.
It simply gets all Group policies in your domain, checks each policy for drive maps (by checking if Drives.xml exists) and gives you a bit of nice output. (ehh.. could be nicer, but anyway… )

See my examples below:
1. Gives you all Drive Map GPO’s plain and formats the output as a table.

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Note: The DriveAction object is not translated to a more friendly name at this time so U, stands for Update, D, for delete and so on. That is also applies on the DrivePersistent output (“Reconnect”).
Update: This is now updated so it gives you a bit of nicer output!

2. Searches for drive maps in a specific GPO.
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3. Exports the output to a csv.

.\Get-GPPDriveMaps.ps1 | Export-Csv DriveMaps.csv -NoTypeInformation


           The script finds the GPP Drive Maps in your domain. 
           File Name: Get-GPPDriveMaps.ps1     
           Author   : Johan Dahlbom, johan[at]dahlbom.eu     
           The script are provided “AS IS” with no guarantees, no warranties, and it confer no rights. 
#Import the required module GroupPolicy
Import-Module GroupPolicy -ErrorAction Stop
throw "Module GroupPolicy not Installed"
        $GPO = Get-GPO -All

        foreach ($Policy in $GPO){

                $GPOID = $Policy.Id
                $GPODom = $Policy.DomainName
                $GPODisp = $Policy.DisplayName

                 if (Test-Path "\\$($GPODom)\SYSVOL\$($GPODom)\Policies\{$($GPOID)}\User\Preferences\Drives\Drives.xml")
                     [xml]$DriveXML = Get-Content "\\$($GPODom)\SYSVOL\$($GPODom)\Policies\{$($GPOID)}\User\Preferences\Drives\Drives.xml"

                            foreach ( $drivemap in $DriveXML.Drives.Drive )

                                {New-Object PSObject -Property @{
                                    GPOName = $GPODisp
                                    DriveLetter = $drivemap.Properties.Letter + ":"
                                    DrivePath = $drivemap.Properties.Path
                                    DriveAction = $drivemap.Properties.action.Replace("U","Update").Replace("C","Create").Replace("D","Delete").Replace("R","Replace")
                                    DriveLabel = $drivemap.Properties.label
                                    DrivePersistent = $drivemap.Properties.persistent.Replace("0","False").Replace("1","True")
                                    DriveFilterGroup = $drivemap.Filters.FilterGroup.Name

The script can of course be extended with a lot more information, and make the output easier to read, but that’s a later project.