HI @John Peter
According to your case description, you want to prevent users from using third-party AI applications in the Office 365 environment.
First, you can monitor and control application permissions: use Microsoft Defender for Cloud Apps to view which users have installed OAuth applications and manage the permissions of these applications. For more information, please refer to https://learn.microsoft.com/en-us/defender-cloud-apps/manage-app-permissions
Second, manage application access:
- Sign in to the Teams admin center and go to Teams apps > Permission policies.
- Select Add.
- Provide a name and description for the policy.
- Under Microsoft apps, Third-party apps, and Custom apps, please select one of the following options for Third-Party apps depending on your need:
- Allow specific apps or copilot agents and block all others
- Block specific apps or copilot agents and allow all others
- Block all apps or copilot agents
- If you selected Allow specific apps and block all others, add the apps that you want to allow:
- Select Allow apps.
- Search for the apps that you want to allow, and then select Add. The search results are filtered to the app developer (Microsoft apps, Third-party apps, or Custom apps).
- After choosing one or more apps, select Allow.
- Select Save.
- Then you can assign it to individual users.
For more information, please refer to https://learn.microsoft.com/en-us/microsoftteams/teams-app-permission-policies
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