The Lenovo System Update allows least-privileged users to perform system updates. To do this, System Update includes the System Update service (SUService.exe). This service runs as the privileged SYSTEM user, creates a temporary user account with Administrator privileges, and starts a GUI application (Tvsukernel.exe) with the new Administrator account. Once the application is closed, the temporary Administrator account is appropriately deleted. However the GUI application contains links to online support and privacy help topics, which, when clicked, start a web browser instance under the temporary Administrator account to display the online topic.
As a result, an attacker who is unprivileged can exploit the web browser instance that is running as Administrator to elevate his or her own privileges to Administrator or SYSTEM.