Tuesday, 8 November 2016

Run PowerShell script on Windows 10 PC through the MDM Channel in Intune

In the last couple of weeks I've been working on an internal project that includes software distribution of Windows apps on MDM enrolled Windows 10 PCs using cloud only Intune deployment. Yes that's right, no SharePoint in this post, but a real world EMS story.
The easiest way to publish classic windows apps on Windows 10 PC that is MDM enrolled will be by publishing Windows Installer through MDM (*.msi) installer.
The important thing with this installer type is that the installation should go without any user interaction required especially when you use "Required Install".
The issue I hit is related to Dell software that is essential for the remote work and almost everyone in the company is using it. However for some reason the software publisher (Dell Software) is considered not trusted in Windows 10. There is this great thing in Windows (since Win 7) called SmartScreen that will pop-up a question asking if we trust the software publisher, before running executable with not trusted publisher. If we manually install the software we are clicking Yes and everithing is fine, the signing certificate is added to the Trusted Publishers certificate store.
However, when we are deploying the package over Intune this issue will cause the installation to fail with exit code 1603.
The way to fix this is to extract the signing certificate and install it in the Trusted Publisher on the target computer or to turn off SmartScreen with a policy, but the second is not a good security practice. The issue is that we cannot deploy cert to the Trusted Publishers store using Intune configuration policy.
My solution is to use PowerShell script that will be deployed and executed over the MDM channel.
The issue is that Intune does not support direct script deployment. There are some articles on the net that are demonstrating how to package batch script in self-extracting executable using IExpress.
However we need to wrap PowerShell script in MSI package suitable for MDM deployment.
I think that this is a very useful technique and I will try to put all the peaces together in this post, so you can deploy and run every PowerShell script on Windows 10 MDM PCs.
The easiest(and free) way to do this will be to create a self-extracting exe with IExpress, wrap the exe in MSI and publish it to Intune.
In order to reliably wrap the PS script in exe I used a script that I found in the TechNet Gallery called Create-EXEFrom.ps1. It will do a really good job wrapping the PS script and you can also add additional files in the package, like in my case I will need Dell Software certificate that should be installed on the target machine. Below is an example line for wrapping MyApp.ps1 script (this will be name used in all sample code) including the certificate we need.

.\Create-EXEFrom.ps1 -PSScriptPath "C:\MyApp.ps1" -SupplementalFilePaths "C:\Certificate.cer"

The exe will be created in the same folder and will be called "MyApp.exe".
The tricky part is that our exe and msi package should also be executed without any interaction required, including bypassing of the SmartScreen. This can be done by properly signing both packages with valid code signing certificate. In my case I have used the certificate that we normally use in bluesource for signing mobile apps. In order to sign the packages you can use the signtool.
If the signing is successful you should see below in your file properties and you should be able to run the exe without SmartScreen alerts.
Publisher Certificate

Now when we have signed exe we should wrap it in MSI package.
The easiest free way for me was to use WiX Toolset to do that. I put together really simple WiX project with only one custom action that will execute the exe. Below you can see the sample xml with the cmd commands I used to compile the WiX project.
If you are new to WiX  you should have your WiX bin folder in the PATH variable to make the cmd script work as it is. In my case it is "C:\Program Files (x86)\WiX Toolset v3.10\bin"(I know it is not the newest version).
Note that the package will be installed under the SYSTEM account and you should consider that in your scripts. You can find how to test MSI package in following article.
Next step is to publish the MSI as "Windows Installer through MDM (*.msi)" installer type as it is shown below.
Intune Publish MSI

The last thing that's left is to deploy the newly published app and maybe running some tests won't be a bad idea :).

I hope that this non-SharePoint post, written by a SharePoint guy will be helpful!

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