How to Allow Local Scripts to Run in Windows PowerShell

Windows PowerShell is a powerful scripting language and command-line shell designed specifically for system administration and automation. By default, PowerShell has strict execution policies that prevent local scripts from running to protect against malicious code. However, there are times when you need to run your own scripts to automate tasks or manage systems efficiently. In this comprehensive guide, we will explore how to allow local scripts to run in Windows PowerShell, covering various methods, best practices, and security considerations. By the end of this article, you will be well-equipped to manage PowerShell script execution policies confidently.

Understanding PowerShell Execution Policies

Before enabling script execution, it’s crucial to understand PowerShell’s execution policies:

1. Restricted: No scripts are allowed to run. This is the default setting for PowerShell.
2. AllSigned: Only scripts signed by a trusted publisher can run.
3. RemoteSigned: Scripts downloaded from the internet must be signed by a trusted publisher.
4. Unrestricted: All scripts can run, but warnings are provided for scripts downloaded from the internet.
5. Bypass: No restrictions; all scripts can run without warnings or prompts.

These policies are designed to protect your system from running potentially harmful scripts.

Method 1: Changing Execution Policy Using PowerShell

One of the most common methods to allow local scripts to run is by changing the execution policy directly in PowerShell. Here’s how to do it:

1. Open PowerShell as Administrator: Click on the Start menu, type PowerShell, right-click on Windows PowerShell, and select Run as administrator.
2. Check Current Execution Policy: To view the current execution policy, type the following command and press Enter:
   Get-ExecutionPolicy

3. Set Execution Policy: To change the execution policy to allow local scripts, use the following command:
   Set-ExecutionPolicy RemoteSigned


   You can replace RemoteSigned with Unrestricted or Bypass depending on your needs.

4. Confirm Changes: When prompted, type Y and press Enter to confirm the changes.

Method 2: Using Group Policy to Change Execution Policy

For environments where multiple machines need the same execution policy, you can use Group Policy to enforce the settings:

1. Open Group Policy Editor: Press Win + R, type gpedit.msc, and press Enter.
2. Navigate to PowerShell Policies: In the Group Policy Editor, go to:
   Computer Configuration > Administrative Templates > Windows Components > Windows PowerShell

3. Enable Script Execution: Double-click on Turn on Script Execution and select Enabled. Choose the desired execution policy (e.g., Allow only signed scripts or Allow all scripts).
4. Apply and OK: Click on Apply and then OK to save the changes.

Method 3: Bypassing Execution Policy for a Single Script

If you need to run a script without changing the system-wide execution policy, you can bypass the policy for a single script:

1. Open PowerShell: Click on the Start menu, type PowerShell, and open it.
2. Run Script with Bypass: Use the following command to run your script:
   PowerShell -ExecutionPolicy Bypass -File "path\to\your\script.ps1"


Method 4: Signing Scripts with a Trusted Certificate

For added security, consider signing your scripts with a trusted certificate. Here’s how to sign a script:

1. Generate a Self-Signed Certificate: Open PowerShell as Administrator and run:
   New-SelfSignedCertificate -CertStoreLocation Cert:\LocalMachine\My -Subject "CN=PowerShellScriptCert"

2. Export the Certificate: Export the certificate to a .pfx file using the Certificates MMC snap-in.
3. Sign the Script: Use the following command to sign your script:
   Set-AuthenticodeSignature -FilePath "path\to\your\script.ps1" -Certificate (Get-Item Cert:\LocalMachine\My\<CertThumbprint>)


Best Practices for Running PowerShell Scripts

1. Use Least Privilege Principle: Always run scripts with the least privileges necessary to reduce security risks.
2. Review Scripts Carefully: Before running any script, review its content to ensure it does not contain malicious code.
3. Keep PowerShell Updated: Regularly update PowerShell to benefit from the latest security features and improvements.
4. Use Trusted Sources: Only run scripts from trusted sources and avoid downloading scripts from unknown websites.

Troubleshooting Common Issues

1. Execution Policy Not Changing: If the execution policy does not change, ensure you are running PowerShell as an administrator.
2. Script Blocked by Antivirus: Some antivirus programs may block scripts. Check your antivirus settings and create exceptions if necessary.
3. Policy Reverts After Reboot: If the policy reverts after a reboot, ensure there are no conflicting Group Policy settings.

Conclusion

Allowing local scripts to run in Windows PowerShell can greatly enhance your ability to automate tasks and manage your system efficiently. By understanding and configuring execution policies, using Group Policy for larger environments, and signing scripts for added security, you can safely run PowerShell scripts tailored to your needs. Remember to follow best practices and review scripts carefully to maintain a secure computing environment.