RMM Powershell Script Building

Published on January 1, 2023

Powershell Scripting for RMM

The idea behind this post is to document a way to setup a build environment for building Powershell scripts running via RMM.

Setup

• Create a 'scripts' folder at the root of C:\
• Download PS Tools
• Place the file PsExec.exe in the 'scripts' folder you created.
• Create your scripts in the same folder.
• Install VSCode with the Powershell extension.
• Verify you're testing your scripts with Powershell 5.1.

Getting Started

RMM Systems such as TacticalRMM use the System account to run their scripts. In order to run under a user context you must use a built-in method with your RMM or use the RunAsUser Powershell module.

1. Open a Powershell window as Admin.
2. Navigate to the root of C:\ and enter the scripts folder.
3. Launch a new Powershell window as System using PsExec.

.\PsExec -i -s "powershell.exe"

4. In the new window navigate to our C:\scripts directory.
5. Verify we are running as System

whoami

Output should look like the following:

nt authority\system

We are now ready to start scripting.

Note: All scripts and testing should be done from the Powershell window running in the system context.

Key Considerations

System Context Limitations

• Limited network access compared to user context
• Different registry hives accessible
• No access to user profile or user-specific applications
• Different environment variables

Best Practices

• Always test scripts in the same context they'll run in production
• Use proper error handling and logging
• Consider user context requirements vs system context capabilities
• Validate permissions and access before executing operations

Common Use Cases

• System maintenance and configuration
• Software installation and updates
• Registry modifications
• Service management
• File system operations
• Security policy enforcement

This setup provides a reliable testing environment that matches how your scripts will execute in production RMM environments.