Block desktop AI apps

Keep AI in the browser, where typing is checked too.

Safe-Desk's Windows app checks what staff paste into the ChatGPT, Claude and Copilot desktop apps. It can't check what they type there by hand. The browser extension checks typed and pasted text alike when a message is sent in Chrome or Edge. If the firm wants no gap, block the desktop AI apps and have staff use the same AI tools in the browser. This page is optional, and it has a cost: staff lose the desktop apps they may be used to.

Why block them

A desktop AI app is a program of its own, not a web page, so the extension never runs inside it. The Windows app covers it by watching the clipboard: when something is pasted into one of these apps, the text goes through the Safe-Desk gate first. Text a person types into the app's own box never passes the clipboard, so nothing checks it. A client's account number typed from memory reaches the AI provider as typed. In Chrome and Edge the extension reads the message box itself when the person presses send, so typing and pasting are both covered.

What staff use instead

The same AI tools in Chrome or Edge: ChatGPT, Claude, Copilot, Gemini, Perplexity and DeepSeek all work in the browser, with the Safe-Desk extension signed in. Three things make that hold:

• The extension is on every staff computer. Once the Chrome Web Store listing is live, force-install it so staff can't remove it; until then each person loads it from Settings. See Install the extension.
• Private and guest windows are off, because extensions don't run there. The policies are in Close private windows.
• The extension runs in Chrome and Edge only. If staff also have Firefox or another browser, either remove it or keep the Windows app installed, which gates AI tabs in other browsers by their window title.

How each app installs

How an app installs decides what can block it. Most of these apps now come as Microsoft Store (MSIX) packages, which Windows identifies by publisher and package name, so one rule covers every version and stops both installing and running. Claude and Perplexity also offer an ordinary per-user .exe installer, which needs a different kind of rule.

The package name is the part before the underscore, such as Microsoft.Copilot. The vendors don't publish the program file names inside these packages, so nothing on this page relies on a file name.

Which method to use

Where an app is already installed, remove it as well as blocking it. As with the Copilot app, a person can uninstall these apps from Settings, Apps, Installed apps. Microsoft's commands for the Copilot app, run in PowerShell as the person, are below; the same two commands work with any package name from the table.

$packageFullName = Get-AppxPackage -Name "Microsoft.Copilot" | Select-Object -ExpandProperty PackageFullName
Remove-AppxPackage -Package $packageFullName

The AppLocker policy

This policy adds packaged app rules only. The first rule is Microsoft's own default rule, which allows every signed packaged app. It has to be there: once a rule collection has any rule, AppLocker blocks everything in that collection the rules don't allow, and without it every other Store app would be blocked too. The next two rules deny the Microsoft Copilot app and the Microsoft 365 Copilot app. A deny rule always beats an allow rule, and on a packaged app it stops both installing and running. Ordinary programs are not affected, because the policy leaves the executable collection empty.

If the firm wants to keep the Microsoft 365 Copilot app, which also gives quick access to Office apps such as Word and PowerPoint, delete the third rule. Your install kit has the same policy ready to copy.

<AppLockerPolicy Version="1">
<RuleCollection Type="Appx" EnforcementMode="Enabled">
  <FilePublisherRule Id="a9e18c21-ff8f-43cf-b9fc-db40eed693ba" Name="(Default Rule) All signed packaged apps" Description="Allows members of the Everyone group to run packaged apps that are signed." UserOrGroupSid="S-1-1-0" Action="Allow">
    <Conditions>
      <FilePublisherCondition PublisherName="*" ProductName="*" BinaryName="*">
        <BinaryVersionRange LowSection="0.0.0.0" HighSection="*" />
      </FilePublisherCondition>
    </Conditions>
  </FilePublisherRule>
  <FilePublisherRule Id="5a81e9c0-33ed-4b06-8a41-75cbadc0ee0c" Name="Safe-Desk: block the Microsoft Copilot app" Description="Typing into this app is not checked by Safe-Desk. Use AI in Chrome or Edge instead." UserOrGroupSid="S-1-1-0" Action="Deny">
    <Conditions>
      <FilePublisherCondition PublisherName="CN=Microsoft Corporation, O=Microsoft Corporation, L=Redmond, S=Washington, C=US" ProductName="Microsoft.Copilot" BinaryName="*">
        <BinaryVersionRange LowSection="*" HighSection="*" />
      </FilePublisherCondition>
    </Conditions>
  </FilePublisherRule>
  <FilePublisherRule Id="dbdc3025-007d-4fdc-8ac5-7ad2cb9be6b6" Name="Safe-Desk: block the Microsoft 365 Copilot app" Description="Typing into this app is not checked by Safe-Desk. Use AI in Chrome or Edge instead." UserOrGroupSid="S-1-1-0" Action="Deny">
    <Conditions>
      <FilePublisherCondition PublisherName="CN=Microsoft Corporation, O=Microsoft Corporation, L=Redmond, S=Washington, C=US" ProductName="Microsoft.MicrosoftOfficeHub" BinaryName="*">
        <BinaryVersionRange LowSection="*" HighSection="*" />
      </FilePublisherCondition>
    </Conditions>
  </FilePublisherRule>
</RuleCollection>
</AppLockerPolicy>

We checked this policy on a Windows 10 Pro computer with Test-AppLockerPolicy: the Copilot app came back denied and Calculator allowed by the default rule. Before you enforce it across the firm, you can set the rule collection to Audit only in the AppLocker console and read the AppLocker event log for a day.

The Microsoft publisher line is the one Microsoft gives for the Copilot app. ChatGPT, Claude and Perplexity are signed by their own companies, and their publisher lines aren't published, so the policy doesn't guess them. Add those three from an installed copy, as described in Adding ChatGPT, Claude and Perplexity.

Microsoft Intune

1. In the Intune admin center, open Devices, Manage devices, Configuration, Create, New policy. Choose platform Windows 10 and later and profile type Templates, Custom.
2. Add an OMA-URI setting. OMA-URI: ./Vendor/MSFT/AppLocker/ApplicationLaunchRestrictions/3f45f0df-69cb-45b8-88b7-2671bf7c81e6/StoreApps/Policy. Data type: String. Value: the policy above from <RuleCollection to </RuleCollection>, without the AppLockerPolicy lines around it.
3. Assign the profile to the group with the firm's staff computers.

The long number in the OMA-URI is a name for Safe-Desk's group of rules. Microsoft asks for a random GUID there so it never clashes with another tool's rules; any GUID works, as long as you use the same one when you change the rules later. Intune applies AppLocker only through a custom OMA-URI like this one. For App Control for Business, Intune has its own policy under Endpoint security, App Control for Business.

Group Policy for a domain

1. Save the policy above as a file, for example safedesk-block-ai.xml.
2. In Group Policy Management, edit a GPO linked to the staff computers. Under Computer Configuration\Policies\Windows Settings\Security Settings\Application Control Policies, right-click AppLocker, choose Import Policy and pick the file. A GPO of its own for these rules keeps them easy to find and change.
3. In the same GPO, under Computer Configuration\Policies\Windows Settings\Security Settings\System Services, set Application Identity to start automatically. AppLocker isn't enforced while that service is stopped.

A small office with no Intune and no domain

On Windows 10 or 11 Pro, AppLocker works as local policy. Do this on each computer, signed in as an administrator:

1. Save the policy above as C:\safedesk-block-ai.xml.
2. Open PowerShell as administrator and run the two lines below. -Merge keeps any AppLocker rules the computer already has. The second line sets the Application Identity service to start automatically; Windows doesn't let the Services window change that setting.
3. Restart the computer.

Set-AppLockerPolicy -XmlPolicy C:\safedesk-block-ai.xml -Merge
sc.exe config appidsvc start=auto

Your install kit also has this as one line to paste, with the policy inside it. To look at or change the rules afterwards, open Local Security Policy (secpol.msc), Application Control Policies, AppLocker.

A staff member who is an administrator on their own computer can change local policy, so this holds only where staff sign in as standard users.

Adding ChatGPT, Claude and Perplexity

AppLocker builds these rules from an installed copy, which fills in the publisher for you. On one computer that has the app installed:

1. Open Local Security Policy, or the GPO, and go to Application Control Policies, AppLocker, Packaged app Rules.
2. Choose Create New Rule. On Permissions, choose Deny and the Everyone group.
3. On Publisher, choose Use an installed packaged app as a reference and pick the app. Move the scope to Package name, so the rule covers every version.
4. Create the rule. Repeat for each app, then export the policy (right-click AppLocker, Export Policy) and deploy it the same way as above.

To see which of these apps a computer has, and each one's publisher, run this in PowerShell as administrator:

Get-AppxPackage -AllUsers | Where-Object { @('OpenAI.Codex','OpenAI.ChatGPT-Desktop','Claude','PerplexityAI.PerplexityApp','Microsoft.Copilot','Microsoft.MicrosoftOfficeHub') -contains $_.Name } | Select-Object Name, Publisher, PackageFamilyName

The .exe copies of Claude and Perplexity

Claude and Perplexity also offer an ordinary installer that puts the app in the person's own profile, where no packaged app rule reaches it. Block those copies with executable rules, in this order:

1. Under Executable Rules, create an Allow rule for Everyone with the path *. Microsoft says a blocklist needs this "allow *" rule; without it, adding any executable rule blocks every other program on the computer, including Safe-Desk's own Windows app.
2. Create a Deny rule for Everyone with a Publisher condition, and browse to the app's program file on a computer that has it.
3. Keep the packaged app rules above. Once executable rules are enforced, Windows blocks every packaged app unless the packaged app collection has rules, and the default allow rule in our policy covers that.

Try executable rules in Audit only mode first. They are where a mistake can stop ordinary programs.

Copilot in Windows and Microsoft 365

Microsoft's own Copilot controls, as Microsoft documents them today:

• The consumer Microsoft Copilot app: Microsoft recommends the AppLocker rule in the policy above, which stops it installing and blocks it if it's already there. The older Turn off Windows Copilot policy (TurnOffWindowsCopilot) is deprecated, and Microsoft says it doesn't apply to the current Copilot app.
• Microsoft also has a Remove Microsoft Copilot app policy (RemoveMicrosoftCopilotApp) for Windows 11 version 24H2 and later. It uninstalls the app only when the Microsoft 365 Copilot app is installed too, the person didn't install Copilot themselves, and it hasn't been opened in 28 days, and people can reinstall it. Microsoft's page contradicts itself on whether it applies to Pro. The AppLocker rule is the dependable route.
• The Microsoft 365 Copilot app installs itself with Microsoft 365 Apps. To stop that, in the Microsoft 365 Apps admin center go to Customization, Device Configuration, Modern Apps settings, Microsoft 365 Copilot app, and clear Enable automatic installation of Microsoft 365 Copilot app. It installs only once, so a copy someone uninstalls isn't put back.
• The Copilot key: Set Copilot Hardware Key (SetCopilotHardwareKey, under User Configuration, Administrative Templates, Windows Components, Windows Copilot) chooses which app the key opens. It needs Windows 11 22H2 with KB5044380 or later, and works on Pro. People can still change the key in Settings.
• Copilot inside Word, Excel, PowerPoint and Outlook: Microsoft documents that admins can block Copilot Chat for all users or chosen groups in the Microsoft 365 admin center, after which it isn't available in the Copilot app, Outlook, Teams or on the web. Turning off the Office setting Allow the use of additional optional connected experiences also restricts Copilot, along with other Microsoft 365 features. Unpinning Copilot Chat does not remove access. We found no Office policy that turns off only the Copilot pane in Word, Excel and PowerPoint. Each person can still turn it off in File, Options, Copilot. To check pastes into those apps instead, use the Windows app's Office setting.
• The Copilot button in Edge's toolbar, for work profiles: Microsoft365CopilotChatIconEnabled set to disabled removes it (Edge 139 or later).

What this doesn't cover

• Google launched a Gemini app for Windows in September 2026. Google Workspace admins turn it off in the Workspace Admin console's Generative AI settings. We haven't confirmed how it installs, so this page gives no rule for it. DeepSeek has a Microsoft Store listing, but we couldn't confirm its package details either.
• Phones and personal computers are outside any Windows policy. The firm's written AI use policy covers them.

Sources, all checked 2026-09-25. Microsoft: Requirements to use AppLocker, App Control for Business feature availability, Packaged app rules in AppLocker, Allow and deny actions, Application Identity service, AppLocker CSP, Intune App Control, Don't run specified Windows applications, Turn off the Store, Manage the Copilot app, WindowsAI policies, Microsoft 365 Copilot app deployment, Manage Copilot Chat. Vendors: OpenAI Windows deployment, Anthropic, Deploy Claude Desktop for Windows, Google Workspace Updates. Package family names from Microsoft's Store catalog and the winget package manifests.