Group Policy

Default Printer At First Logon via Group Policy

Deploying a network printer via Group Policy is pretty easy. In Group Policy Management Editor, you go to User Configuration > Preferences > Control Panel Settings > Printers and right click to create a new Shared Printer. Configure the options which are pretty straight forward.

Something doesn’t go right though, if you use the option ‘set this printer as the default printer’. The printer won’t actually be set as default for the first login. As it’s set to Update though, this will get fixed next time Group Policy runs.

However, if you have the Action set to ‘Create’, it only gets one chance to set the default printer – at the time of creation. That fails, and it doesn’t get a chance to set the default printer again.

Why does it fail to set the default printer at first logon? You’ll see an event viewer application error like this:

The user ‘HP Printer’ preference item in the ‘Define Printers {XXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}’ Group Policy object did not apply because it failed with error code ‘0x80070709 The printer name is invalid.’ This error was suppressed.

There’s a clear Microsoft Support Article that explains why – in summary, Windows isn’t ready yet to change something on the printer between the time it creates the printer, and then tries to make it default as they’re two separate actions.

However, we can work around this by deploying a registry entry that sets the default printer. This 11 year old article is still correct in that it shows the registry value to change:

HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows

REG_SZ - Device
Value - \\adamfowlerit\printer,winspool,Ne04:e

Setting this via registry as an ‘Apply once and do not reapply’ with any other logic matching your printer deployment policy, should end up with the printer as a default on first logon.

This is a problem that’s been around for many years, but the first time I’ve hit it!

How To Suppress “A website wants to open web content using this program on your computer”

As part of Windows 10 testing, I came across this prompt.

Internet Explorer Security
A website wants to open web content using this program on your computer
This program will open outside of Protected mode. Internet Explorer's 
Protected mode helps protect your computer. If you do not trust this 
website, do not open this program.
Name: XXX
Publisher XXX

Do not show me this warning for this program again

When you open a file from a site that is an internet site zone (that is, not in your intranet zone or trusted sites zone) for Internet Explorer 11, you’ll be prompted with the above Internet Explorer Security prompt.

This doesn’t happen for IE11 on Windows 7.

Because there’s a tickbox that lets a user suppress the prompt in future for when that particular program is called, it may just get in the way for users the first time they see it and cause confusion. It’s on a per app basis – once you allow Microsoft Word, it’s allowed for all sites, but that won’t allow Microsoft Excel.

To stop this prompt for commonly used applications, you can use Group Policy to roll out registry settings that would be applied if the user had ticked the box already for that app.

The registry settings live in HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Low Rights\ElevationPolicy\ with a unique GUID for each application.

Here’s a screenshot showing settings for Microsoft Word:

Here’s the raw registry settings:

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Low Rights\ElevationPolicy\{342263D0-430D-4325-919B-666CE94C4334}]
"Policy"=dword:00000003
"AppPath"="C:\\Program Files (x86)\\Microsoft Office\\Office16"
"AppName"="WINWORD.EXE"

This can be saved into a .reg file, imported onto your PC, then using Group Policy’s Registry Import Wizard, imported into a Group Policy and deployed. Again, this will need to be done for each application you want to automatically allow.

Chinese Characters in IE11, Edge and Windows 10

I recently worked on an issue where all Windows 10 users were seeing two strange display issues on certain websites via Internet Explorer 11 and Edge. There were two noticeable symptoms:

  • Chinese characters would show in particular locations on many websites. These were often buttons, but sometimes other symbols.
  • Buttons would be completely blank. The buttons themselves worked, which you could either use if they had a graphical representation of the button still, or you knew where to click.

This was even presenting itself in Office 365 – I couldn’t see the Notifications, Settings or Help buttons, and they would instead show as blank boxes.

This was found while piloting Windows 10 from Windows 7. The visible options in Internet Explorer seemed identical. and other browsers weren’t affected – Chrome could display these sites perfectly fine.

I worked out what the problem and fix was (jump to the end if you want that now), but here’s the story on how we got to this broken state:

As part of prepping for Windows 10, I followed Microsoft’s Security Baseline documentation which contains a handy Excel spreadsheet, with recommendations on what Group Policy settings you should use for best security practises. I followed this (I’ve linked to a newer version) and made choices based on understanding each option, and what worked for us. There were very few settings I didn’t follow exactly.

One of these settings was ‘Untrusted Font Blocking‘. The document recommended enabling this, to stop untrusted fonts being used as they’re a security risk – the loading of a font can allow elevated privileges, and has been used before. Made sense to me, so I enabled it.

This is what Group Policy says about Untrusted Font Blocking:

This security feature provides a global setting to prevent programs from loading untrusted fonts. Untrusted fonts are any font installed outside of the %windir%\Fonts directory. This feature can be configured to be in 3 modes: On, Off, and Audit. By default, it is Off and no fonts are blocked. If you aren’t quite ready to deploy this feature into your organization, you can run it in Audit mode to see if blocking untrusted fonts causes any usability or compatibility issues.

Eventually with a lot of testing and googling, I tried disabling this option – and it worked. Once you know the fix to a problem, it’s really easy to work backwards to find out more about it.

It turns out that in simple terms, websites can present their own fonts to use. It may be easier to present an arrow that’s from a font, rather than making a graphic of a font. Usually the site will load the font on the fly, but blocking that means the site fails back to a ‘best match’ on the font, which seems to be a font for Chinese characters, or a font that has a blank character for the matched result. Makes sense.

Microsoft changed their mind on this recommendation, only a month ago from time of writing. That recommendation change is worth reading, as it explained why they did it, and why they’re now changing their mind. The good news is that you’re not losing security by abandoning this setting, as the way fonts are parsed has changed from kernel to sandboxed user mode.

TL;DR version:

Turn off Untrusted Font Blocking through either of these methods:

Group Policy – Disable or change to Not Configured: Computer Configuration > Policies > Administrative Templates > System > Mitigation Options > Untrusted Font Blocking

Registry Setting – HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Kernel\ – QWORD MitigationOptions

  • To turn this feature on. Type 1000000000000.
  • To turn this feature off. Type 2000000000000.
  • To audit with this feature. Type 3000000000000.Important
    Your existing MitigationOptions values should be saved during your update. For example, if the current value is 1000, your updated value should be 1000000001000

Deploying Printers In Windows 10

Printers are pretty easy to deploy via Group Policy. It’s easy to configure a Group Policy Preference to deploy a printer, but there’s a few gotchas that may prevent the printer from actually getting installed client side.

The first thing to check is Event Viewer > Applications. If Group Policy attempts to add a printer but fails, it should be logged as a warning and give an idea on what the problem is. If you’re stuck – enable Group Policy Preferences Logging and Tracing for Printers, and see if you get more data.

For Windows 10, depending at what patch level you’re at, and what drivers the print server has, and if those drivers are packaged or not you’ll probably have to enable more policies to make printers deploy. If you don’t, you may see this error in Event Viewer: “Group Policy Object did not apply because it failed with error code ‘0x80070bcb The specified printer driver was not found on the system and needs to be downloaded.’ ”

There’s a lot of information out there on this topic – but generally, the main reason a printer won’t automatically install is because of UAC. If you try to manually install one of these printers, you’ll get the ‘Do you trust this printer’ warning, and even after continuing on that, the install may fail.

There’s two Group Policies to configure to get around this, which I found blogged at Systemcenterdudes so please read their post – but you need to enable these two policies:

Computer Configuration > Policies > Administrative Templates > Printers – Package Point and Print

Computer Configuration > Policies > Administrative Templates > Printers – Point and Print 

In both of the policy settings, you may need to specifiy your print servers. It wouldn’t work for me until I did – and it’s a better security approach to do this anyway.

Once that was done, printers were then able to be installed automatically via Group Policy. There’s some other ways I’ve read to change how the drivers work, push out registry fixes etc – but to me this seems the simplest and safest approach (assuming it works for you too!).

If you’ve had a different experience or the above doesn’t work, please share!

Hide Edge Button from IE11 Tab

A feature that’s popped up in IE11, is the little Edge icon next to the new tab icon. Not something I’d want in the enterprise space:

Thankfully, it’s easy to disable. There’s a group policy policy called “Hide the button (next to the New Tab button) that opens Microsoft Edge” which can be found in User Configuration\Administrative Templates\Windows Components/Internet Explorer\Internet Settings\Advanced Settings\Browsing\ . 

If you can’t see this policy, make sure you have the latest ADMX files from Microsoft – Windows 10 1703. If you haven’t had much to do with adding ADMX files to your environment before – they should be centralised, and Microsoft have a great guide you can follow.

Bonus tip – If you have internal sites that use a single word (e.g. intranet) you can enable the policy “Go to an intranet site for a one-word entry in the Address bar” which will check for an internal site starting with that name before using the word in your default search engine. This one’s actually an old policy that I hadn’t noticed before!

 

Group Policy Preferences – Replace Existing File

I’ve written before on how great Group Policy Preferences are, and thought I’d write a quick ‘how to’ on a likely common scenario – replacing an older file with a new one, but only if it already exists.

Pushing out a file via Group Policy Preferences is quite easy and has been around for a long time.

When creating a new file rule, you’ll see 4 options under ‘Action’ – Create, Replace, Update and Delete:

gpp2

Create will only copy the file from the source to the destination if the file doesn’t exist at the destination
Replace will actually remove a file (if one exists), and copy the source to the destination regardless if a file existed or not
Update is the misleading one, it will modify the file attributes of the destination file to match the source – if the files themselves are different, it won’t copy them. If the file doesn’t exist, it will copy the file to the destination though!
Delete will delete the file(s) specified.

None of these provide a solution to ‘Replace file only if it exists’ though. There’s two obvious ways this can be achieved; you can use ‘Replace’ but this will continually replace the file every time Group Policy is run, which in the user context is every 90 minutes. You also can’t use the option ‘Apply once and do not reapply’ because it will run regardless of the file existing or not – which means if the file isn’t there before group policy runs, the file may be replaced by a software install or other mechanism, and with the order out of whack, resulting in the wrong file being left there in the end.

The next logical way to make sure the order is correct is to use Item Level Targeting. Under the ‘Common’ tab, you can tick the box for ‘Item Level Targeting’ and point to the file in question:

gpp3

This will only run once though, and that is regardless of the ‘Item Level Targeting’ being true or false. That only controls whether the policy does what it’s configured to do, at the client side it’s still ‘run’ the policy, it just had nothing to do.

thommck had the best answer on how to get around this that I’ve found – use a custom WMI query. You’ll need to remove the ‘Apply once and do not reapply’ tick, but the file itself will only be copied over when both targeting rules are true. Please read his post for all the details, but the second item will need to be a WMI query, and have a string similar to this:

SELECT LastModified FROM CIM_DataFile WHERE name=”C:\\windows\regedit.exe” AND LastModified < ‘20160701000000.000000+060’

This is checking the date of the file, and will only be ‘true’ if it’s less than that date.

Keep in mind that this is less than ideal, as WMI queries aren’t the most efficient way of processing group policy preferences, but it may be better than copying files around your network to every PC, every 90 minutes.

Search Group Policy with PowerShell Script

I was looking for a certain Group Policy Preferences setting, where a registry value was being changed. Resultant Set Of Policy (RSOP) won’t help with these, and I couldn’t see a nice PowerShell command for searching through Group Policies.

I put the shoutout on Twitter to see who could help, and Tony Murray came back quickly with a script he’d created, and promptly uploaded to the Microsoft TechNet Gallery where I could download it.

It’s a reasonably simple script (which for me would have taken at least an hour to do beginning to end!) and is very easy to use.

Running the ps1 file will provide you with a prompt, asking what string you’re searching for. Enter the string, and it’ll give back all the Group Policy objects, along with if there was a match or not:

match

After seeing it work, I decided to make one slight change; I removed this section:

    else { 
        Write-Host "No match in: $($gpo.DisplayName)" 
    } # end else 

which results in the script only showing matches, and displaying no output otherwise. Handy if you have a long list of objects to look through!

Thanks again Tony for both writing this and sharing it!

 

Update 20th Dec 2018

Although the script is really useful, it didn’t like special characters for the search string which makes it hard to search for registry settings. I’ve changed how the search function works on a single line, and it now seems to be happy with special characters. This also appears to come at a cost of speed, it’s a bit slower to search. I’m letting Tony know so he can consider updating his master script, but if you want to do it, just replace the line:

if ($report match $string) {

with

if ($report.contains(“$string”) -eq $true) {

Again since it’s not my script I don’t really want to put the entire end result up, but here’s how it should look after the comments section: