Powershell: Force full update of Root CA store

By default, Windows comes only with a small set of Root CA’s in the trusted Root CA store. These are enough to get you started, but as soon as you visit a website that uses HTTPS and the Root CA that has issued the certificate is not in your trusted Root CA list, the Root CA certificate is downloaded from Windows Update.

Generally, this is a good solution, as long as your clients can reach Windows Update to start with and they aren’t non-persistent VDI clients.

Currently, we are noticing that Internet Explorer sometimes hangs for a few seconds and then continues. At the same time, an event is logged ( CAPI2 4097 ) telling you that the Root CA has been updated. Again, this works fine on persitent VDI’s, laptops, desktops and servers. On a non-persistent VDI however, this process is repeated for every CA on every session for every user. Not so nice.

Currently, we are still testing what yields the best results. I’ve written the script below, which creates a directory on the C:\ disk, downloads all root CA’s from Windows Update into this directory and then imports every .crt in the Root CA store, then removes the directory. I’ve imported this script into RES Workspace and is being run during logon. As it’s run in the background there is no noticable delay in logon time, and after logon, about 380 CA’s (we have some internal and private CA’s added as well) are visible in the certificate manager.

You could consider adding this as a step in your SCCM task sequence or however you create your VDI image, so it’s not performed during logon. However, this means that CA’s that are added later will have to be downloaded on demand, and also CA’s that are revoked or updated after you’ve made your image will have to be updated on demand as well.

md C:\Certs
certutil -syncwithWU C:\Certs
$files = Get-ChildItem -Path 'C:\certs\*' -Include '*.crt'
Foreach ($file in $files) {
$importfile = "$file"
certutil -addstore -f Root "$importfile"
write-host $importfile
rd c:\certs -Recurse

Update: Oh yea! As you can see, i’m using Certutil to import the certificates. That’s because my current customer is still running Windows 7. When you’re on Windows 8/2012 and higher, you should ofcourse use the PS commandlet “Import-Certificate”, together with the appropriate config ofcourse.

Powershell: Check and Toggle Numlock during logon

This is one that comes up anywhere, especially in VDI/RDS-type environments: Numlock.

In my experience there are no real good ways of controlling this without scripts, too many variables, as the final state of numlock depends on the state on the client computer, the VM and whatever settings are in the user profile.

The powershell script below first checks for the state of the numlock key: If ([console]::NumberLock -eq $False), and when False, proceeds to send the command to toggle it, turning it on.


If ([console]::NumberLock -eq $False) {
$wsh = New-Object -ComObject WScript.Shell

Windows Driver Installation: Searching Windows Update..

PolicyBy default, when you plug in a USB device, Windows will search Windows Update for the latest drivers. While this might be a fantastic solution for your home computer, it’s useless in an organization, because usually Windows Update is blocked so it will sit for about 5 minutes searching, until it times out and uses the locally available driver or tell you that you need to go get some drivers yourself.

So, lazy admin as you are, you fire up Google, and find a policy:

Computer Configuration\Administrative Templates\System\Internet Communication Management\Internet Communication settings\Turn off Windows Update device driver searching.

Well.. wrong. This policy has been deprecated and will only work up to Vista. For some reason the new policy has had very little coverage on the web, so it took some time to find it.

The new policy, which you should use with Windows 7 or later, can be found at:

Computer Configuration\Administrative Templates\System\Device Installation\Specify Search Order for device driver source locations

Select the option “Do not search Windows Update” and you’re gold.