The ESP32 system on a chip (SoC) that powers the Meatmeet Pro was found to have JTAG enabled. By leaving JTAG enabled on an ESP32 in a commercial product an attacker with physical access to the device can connect over this port and reflash the devices firmware with malicious code which will be executed upon running. As a result, the victim will lose access to the functionality of their device and the attack may gain unauthorized access to the victims Wi-Fi network by re-connecting to the SSID defined in the NVS partition of the device.
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.