Principals with the Intune Administrators role are able to execute arbitrary PowerShell scripts on devices that are joined to the Azure Active Directory tenant.
First, have your PowerShell script ready to go and save it somewhere as a PS1 file. Take all the necessary operational security (opsec) and AMSI-bypass steps you want at this point, keeping in mind the script will run as the SYSTEM user unless you specify otherwise. Also keep in mind that the script will be written to disk, so take whatever AV bypass measures you need as well.
Next, log into the Azure web portal as the user with the “Intune Administrator” role activated. After authenticating, access Endpoint Manager at https://endpoint.microsoft.com.
Click on “Devices” on the left, which takes you, unsurprisingly, to the devices overview. Click on “Scripts” under the “Policy” section to go to the scripts management page. Click “Add,” then click “Windows 10”.
This will bring you to the “Add Powershell Script” page. On this first page, you’ll enter a name for the script and a brief description. On the next page, click the folder and then select your PS1 from the common dialogue window. You’ve now got three options to configure, but can leave them all in the default “No” position. Most interestingly, keeping the first selection as “No” will cause the script to run as the SYSTEM user.
Click next, and you’ll see the page that lets you scope which systems and users this script will execute for. You can choose to assign the script to “All devices,” “All users,” or “All users and devices.” If you leave the “Assign to” dropdown at its default selection of “Selected groups,” you can scope the script to only execute on systems or for users that belong to certain security groups. The choice is yours: run the script on every possible system or constrain it to only run on certain systems by scoping it to existing security groups or by adding specific devices or users to new security groups.
Click “Next” and you’ll see the review page which lets you see what you’re about to do. Click “Add” and Azure will begin registering the script. At this point, the script is now ready to run on your target systems. This process works similarly to Group Policy, in that the Intune agent running on each device periodically checks in (by default every hour) with Intune/Endpoint Manager to see if there is a PowerShell script for it to run, so you will need to wait up to an hour for your target system to actually pull the script down and run it.
When the Intune agent pulls down and executes PowerShell scripts, a number of artifacts are created on the endpoint - some permanent and some ephemeral.
Two files are created on the endpoint when a PowerShell script is executed in the following locations:
C:\Program files (x86)\Microsoft Intune Management Extension\Policies\Scripts
C:\Program files (x86)\Microsoft Intune Management Extension\Policies\Results
The file under the “Scripts” folder will be a local copy of the PS1 stored in Azure, and the file under the “Results” folder will be the output of the PS1; however, both of these files are automatically deleted as soon as the script finishes running. There are also permanent artifacts left over (assuming the attacker doesn’t tamper with them). A full copy of the contents of the PS1 can be found in this log file: