PrintNighmare-safe Printer Management

Hello Folks,

Hopefully this post will help many out there who may struggle to emulate a Point-and-Print solution but without compromising the security of the corporate network.

For those new to the topic, Microsoft tightened the security of the printing subsystem as a result of a number of critical vulnerabilities, commonly referred to as PrintNighmare - details here. The fix consists in limiting driver installation to administrators only. To clarify, before the PrintNightmare security measures, end users were allowed to install printer drivers.

Given that lots of administrators have implemented Point-and-Print, this security measure broke printing for lots of organizations. Microsoft provided a workaround, which effectively cancels the security measures, by means of a Registry setting. It is well documented in various places such as this. Basically by implementing the Registry hack, you'd revert back your printing subsystem to its pre-patch, vulnerable state  by allowing end users to install printer drivers.

The core of the problem is to get the drivers onto the client computers without user interaction.

This post is meant to address the following issues:

1. Install printer drivers on users' computers.
2. Eliminate security prompts and user interaction.
3. Automate the process and centralize administration.
4. Maintain security (no need to undo Microsoft's security measures via the Registry hack).
5. Use only built-in tools pre-canned with the operating system.

CAVEAT: I do not claim by any means that it is a perfect solutions. There is plenty of room for improvement. Likely you'll have to adapt it to your needs in case you run a large, multi-department and/or geographically distributed environment. Make it suit your needs.

In a nutshell the process is as follows:

1. Set up the print server: install drivers, create ports, install, configure and share printers (ensure they are published in Active Directory).
2. Create a new GPO or nominate an existing one to distribute printers to users. Create shared printer definitions in User Configuration / Preferences / Control Panel Settings / Printers. Link it to the OU holding your users.
3. Use item-level targeting to define who gets what printer. Also make sure that the process runs in the logged-on user's security context.
4. On the print server, export device drivers to a shared folder that client computers can access.
5. Create a new GPO or nominate an existing one to distribute a computer startup script. Link it to the OU holding your client computer objects.
6. Reboot the client computers to make them run the computer startup script. The script imports the drivers that have been exported at point 4 above. It runs in the System security context, administrator by definition, therefore no security prompt is displayed.
7. Users will be connected to their printers as defined in the GPO at point 2 above.

At points 2 and 5, depending on your environment, you may use a single, dedicated GPO linked to both user and computer OUs (or to the domain root to that matter if such is your environment - I recommend against it though).

At the core of the solution there are two PowerShell scripts:

1. A server-side script running on the print server that exports drivers.
2. A client-side script running on client computers that imports pre-filtered drivers of shared printers.

We will not go into configuring GPOs and shared printer setup as it is well documented on the Internet. The 7 steps above should provide sufficient information to get you started.

Following is the two-step process to set up the scripts.

I. Setting up the print server

The following is to be done on the print server:

1. Create a folder to store the exported drivers, e.g. C:\SharedPrinterDrivers.
2. Share the folder, e.g. Drivers$ (I like to create hidden shares for such things).
3. Grant the Domain Computers security group Read permission at share and NTFS level.
4. Create the driver export script and save it to folder, e.g. C:\Scripts\ExportSharedPrinterDrivers.ps1
5. Create a scheduled task to run the driver export script on a regular basis.

My suggestion is to run the script daily, early in the morning, before users power on their computers,. This way drivers updated overnight by Windows Updates (or equivalent server maintenance tools) would be captured in the export and distributed to users when they log on.

The driver export script:

List Details of AD-joined Servers

Hello again,

I had a task recently to install an update on a number of AD domain-joined servers. I had to make sure that no server was missed.

In my case checking that all servers are at a given build number was sufficient.

Here is the one-liner that will display this information:

$arrServers = @(); Get-ADComputer -Filter * -Properties OperatingSystem | ?{$_.OperatingSystem -match "Server"} | sort Name | ForEach-Object {$Name = $_.Name; $OS = $_.OperatingSystem; $Version = $null; $Build = $null; $osDetails = $null; $osDetails = Invoke-Command -ComputerName $Name -ScriptBlock {Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion"}; if ($osDetails.CurrentMajorVersionNumber) {$Version = $osDetails.ReleaseId; $build = $osDetails.CurrentMajorVersionNumber.ToString() + "." + $osDetails.CurrentMinorVersionNumber.ToString() + "." + $osDetails.CurrentBuildNumber.ToString() + "." + $osDetails.UBR.ToString()}; $arrServers += New-Object -TypeName PSObject -Property @{Name = $Name; OS = $OS; Version = $Version; Build = $Build}}; $arrServers | ft

Open PowerShell as Administrator and simply paste the script.

To be noted that it does no error handling except for checking for the existence of the CurrentMajorVersionNumber value of the "HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion" Registry key as a rudimentary means to filter out old operating systems. If you'd like something more sophisticated then you'll want it turned  into a proper script with all the bells and whistles.

However, for a one-off quick check it does the job.

Sample output:

Have a great scripting day!

Find Entra Connect / AADConnect Versions in Partner Tenants

Hello again,

I have been tasked to find out which of our M365 client tenants need their Entra Connect / AADConnect agent updated. Came up with this little script:

Connect-MsolService

$tenants = Get-MsolPartnerContract

$arrCI = @()

ForEach ($tenantId in ($tenants).TenantId) { $arrCI += Try { Get-MsolCompanyInformation -TenantId $tenantId -ErrorAction Stop} Catch { "Error" } }

$arrCI | ?{$_.DisplayName} | sort DisplayName | select DisplayName,DirSyncClientMachineName,DirSyncClientVersion,DirectorySynchronizationStatus

Tweak it to your liking.

Enable Remote Event Log Access

I was in a situation recently when I had to collect RDS host logon details from a farm with 20-odd servers. While I already had a script that collected this kind of information from another set of servers, it didn't work on this particular farm.

As it turned out, the firewall blocked RPC access to event logs. I had to enable the "Remote Event Log Management (RPC)" firewall rule on each server.

Yes, it can be done manually one by one. No, that's not how I prefer to do things at scale.

Run this one-liner as administrator on the RDS Broker server to do it the quick way:

(Get-RDServer -Role RDS-RD-SERVER).Server | ForEach-Object { Invoke-Command -ComputerName $_ { Set-NetFirewallRule -DisplayName "Remote Event Log Management (RPC)" -Enabled true }}

More generically, you can run the following to achieve the same for any firewall rule on an arbitrary list of servers:

@("SERVER1","SERVER2", ..., "SERVERn") | ForEach-Object { Invoke-Command -ComputerName $_ { Set-NetFirewallRule -DisplayName "display_name_of_firewall_rule" -Enabled true }}

Replace -Enabled true with -Enabled false to disable the rule.

A word of caution: since we are playing with firewall rules on a large number of servers, one wrong parameter will have a spectacular effect in a bad way - have your your resignation letter handy. Before you unleash your custom code on your entire infrastructure, make sure you've tested it thoroughly.

You've been warned.

Have fun!