Interactive Services Detection

The Interactive Services Detection (UI0Detect) service enables notification of user input for interactive services, which enables access to dialog boxes that are created by interactive services. If this service is stopped, notifications of new interactive service dialog boxes no longer function and there might no longer be access to interactive service dialog boxes. This service supports the service isolation feature.

In Windows XP, Windows Server 2003, and earlier versions of the Windows operating system, all services run in the same session as the first user who logs on to the console. This session is called Session 0. Running services and user applications together in Session 0 poses a security risk because services run at elevated privilege; and therefore, they are targets for malicious users who are looking for a way to elevate their own privilege level.

The Windows 7 and Windows Server 2008 R2 operating systems mitigate this security risk by isolating services in Session 0 and making Session 0 noninteractive. In these operating systems, only system processes and services run in Session 0. The first user logs on to Session 1, and subsequent users log on to subsequent sessions. This means that services never run in the same session as users' applications. Therefore, users are protected from attacks that originate in application code.

Because Session 0 is no longer a user session, services that run in Session 0 do not have access to the video driver. This means that any attempt that a service makes to render graphics fails. For example, if a device installer runs in Session 0 and the installation program creates a dialog box in Session 0 that requires user input to continue, the device installation never completes because the user does not see the dialog box. From the user's perspective, the device installer has stopped responding because it has stopped progressing and the user has no way to resume it. Basically, any functionality in a service or a service-hosted driver that assumes the user is running in Session 0 does not work correctly in Windows 7 and Windows Server 2008 R2.

As a result of this issue, the option to enable the Interactive Service Detection service is available for customers who have services from earlier versions of Windows that send user interaction dialog boxes to Session 0 instead of to the corresponding user's session.

This service is installed by default and its startup type is Manual. The service starts only when a visible dialog box that is not a command window is detected. If the service is started, users are notified when a dialog box or window (including a command window) appears in Session 0. Information about each of the last 10 dialog boxes appears in turn if more information is shown. This helps to ensure that when you test the deployment of the new operating you are aware of services from earlier operating systems in their environment, and they have the opportunity to contact the vendors for updated services.

The service detects these visible dialog boxes or windows and sends a notification to the user. Users may choose to:

  • Respond to the dialog box immediately by clicking a button to switch to Session 0, interact with the task dialog box, and then switch back to their session.
  • Be reminded again in five minutes. The reminders continue until the dialog box closes.

If this service is disabled, users do not receive notifications when the devices or services send dialog boxes to Session 0.

When the Interactive Services Detection service is started in its default configuration, it logs on by using the Local System account, and it is allowed to interact with the desktop.

This service is not dependent on any other system service, nor is any service dependent on it.

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