The CleverDisplay BlueOne hardware player is designed with its USB interfaces physically enclosed and inaccessible under normal operating conditions. Researchers demonstrated that, after cicumventing the device’s protective enclosure, it was possible to connect a USB keyboard and press ESC during boot to access the BIOS setup interface. BIOS settings could be viewed but not modified. This behavior slightly increases the attack surface by exposing internal system information (CWE-1244) once the enclosure is removed, but does not allow integrity or availability compromise under standard or tested configurations.
The chip does not implement or does not correctly perform access control to check whether users are authorized to access internal registers and test modes through the physical debug/test interface.
A device’s internal information may be accessed through a scan chain of interconnected internal registers, usually through a JTAG interface. The JTAG interface provides access to these registers in a serial fashion in the form of a scan chain for the purposes of debugging programs running on a device. Since almost all information contained within a device may be accessed over this interface, device manufacturers typically insert some form of authentication and authorization to prevent unintended use of this sensitive information. This mechanism is implemented in addition to on-chip protections that are already present. If authorization, authentication, or some other form of access control is not implemented or not implemented correctly, a user may be able to bypass on-chip protection mechanisms through the debug interface. Sometimes, designers choose not to expose the debug pins on the motherboard. Instead, they choose to hide these pins in the intermediate layers of the board. This is primarily done to work around the lack of debug authorization inside the chip. In such a scenario (without debug authorization), when the debug interface is exposed, chip internals are accessible to an attacker.