Block windows app installation with elevated privileges using GPO

In an enterprise IT environment, controlling the permissions and actions of the Windows Installer is crucial for maintaining security and consistency. Allowing the Windows Installer to use elevated permissions during program installations can lead to unexpected changes and potential security vulnerabilities. In this article, we will guide system administrators through the process of creating a Group Policy Object (GPO) to deny Windows Installer elevated permissions. This step-by-step guide includes advanced configurations and real-world use cases.

Why Control Windows Installer Permissions

Windows Installer is a core component of the Windows operating system responsible for installing, updating, and managing software. By default, it runs with elevated privileges, which means it can make system-wide changes. This can be problematic in enterprise environments where strict control over software installations is necessary for security and compliance reasons.

Here are some reasons why controlling Windows Installer permissions is essential:

1. Security: Allowing Windows Installer to run with elevated permissions can lead to unauthorized software installations or changes, creating potential security vulnerabilities.
2. Consistency: Ensuring that software installations follow a standardized configuration helps prevent compatibility issues and streamlines troubleshooting.
3. Compliance: In regulated industries, controlling software installations is often a compliance requirement.

Prerequisites

Before proceeding, make sure you have the following:

• Administrator Rights: You must have administrative privileges in your Active Directory (AD) environment.
• Group Policy Management Console (GPMC): This tool must be installed and accessible.

Step-by-Step Instructions

Step 1: Open Group Policy Management Console (GPMC)

Launch the GPMC by typing “Group Policy Management” in the Start menu search or by running gpmc.msc.

Step 2: Create or Edit a Group Policy Object (GPO)

• To create a new GPO, right-click on the domain or an Organizational Unit (OU) and select “Create a GPO in this domain, and Link it here…”.
• To modify an existing GPO, locate it under the appropriate domain or OU, right-click it, and select “Edit”.

Step 3: Navigate to Software Restriction Policies

In the Group Policy Management Editor, navigate to: Computer Configuration → Policies → Windows Settings → Security Settings → Software Restriction Policies.

Step 4: Create a New Software Restriction Policy

• Right-click on “Software Restriction Policies” and select “New Software Restriction Policies”.

Step 5: Define Additional Rules

• In the right pane, right-click on “Additional Rules” and select “New Path Rule”.
• Browse and select the path to the Windows Installer executable, which is usually located at C:\Windows\System32\msiexec.exe.

Step 6: Set Security Level

• After selecting the path, set the security level to “Disallowed”.
• Click “OK” to save the rule.

Step 7: Apply and Enforce the GPO

• Click “OK” or “Apply” to save the changes.
• Link the GPO to the relevant OU(s).
• The policy will be applied at the next Group Policy refresh cycle. To expedite, run gpupdate /force on the client machines.

Advanced Configuration and Use Cases

1. Custom Error Messages

Configure custom error messages for users or administrators who attempt to install software that requires elevated permissions. This helps communicate the policy and its reasons clearly.

2. Exceptions for IT Personnel

Consider creating exceptions for IT personnel or designated administrators who may need to install software requiring elevated permissions for specific tasks. This ensures that essential system administration tasks can still be performed.

Real-World Use Cases

1. Security Software: Prevent unauthorized changes to security software installations to maintain a secure environment.
2. Compliance: Comply with regulatory requirements that mandate strict control over software installations and changes.
3. Consistency: Ensure that all software installations adhere to a standardized configuration, reducing the risk of compatibility issues.

Security Considerations

• Regular User Education: Communicate the policy changes to regular users to ensure they understand the reasons behind the restrictions and to minimize frustration.
• Exception Handling: Be prepared to handle exceptions for IT personnel or specific tasks that require elevated permissions.

Troubleshooting

• Policy Not Applied: If the GPO does not apply as expected, use tools like Resultant Set of Policy (RSoP) or gpresult for diagnosis and troubleshooting.
• Executable Path: Ensure that the path to msiexec.exe in the GPO matches the actual path on client machines.

Conclusion

Creating a GPO to deny Windows Installer elevated permissions during program installations is a crucial step in maintaining software consistency and security within an organization. By following the detailed steps outlined in this guide, system administrators can effectively control software installations, enhance security, and reduce the risk of unauthorized changes.