[lulagain]

Update 3/9/25: After receiving concerns about the use of the term 'backdoor' to refer to these undocumented commands, we have updated our title and story. Our original story can be found here.

The ubiquitous ESP32 microchip made by Chinese manufacturer Espressif and used by over 1 billion units as of 2023 contains undocumented commands that could be leveraged for attacks.

The undocumented commands allow spoofing of trusted devices, unauthorized data access, pivoting to other devices on the network, and potentially establishing long-term persistence.

This was discovered by Spanish researchers Miguel Tarascó Acuña and Antonio Vázquez Blanco of Tarlogic Security, who presented their findings yesterday at RootedCON in Madrid.

"Tarlogic Security has detected a backdoor in the ESP32, a microcontroller that enables WiFi and Bluetooth connection and is present in millions of mass-market IoT devices," reads a Tarlogic announcement shared with BleepingComputer.

"Exploitation of this backdoor would allow hostile actors to conduct impersonation attacks and permanently infect sensitive devices such as mobile phones, computers, smart locks or medical equipment by bypassing code audit controls."

The researchers warned that ESP32 is one of the world's most widely used chips for Wi-Fi + Bluetooth connectivity in IoT (Internet of Things) devices, so the risk is significant.

Discovering undocumented commands in ESP32

In their RootedCON presentation, the Tarlogic researchers explained that interest in Bluetooth security research has waned but not because the protocol or its implementation has become more secure.

Instead, most attacks presented last year didn't have working tools, didn't work with generic hardware, and used outdated/unmaintained tools largely incompatible with modern systems.

Tarlogic developed a new C-based USB Bluetooth driver that is hardware-independent and cross-platform, allowing direct access to the hardware without relying on OS-specific APIs.

Armed with this new tool, which enables raw access to Bluetooth traffic, Tarlogic discovered hidden vendor-specific commands (Opcode 0x3F) in the ESP32 Bluetooth firmware that allow low-level control over Bluetooth functions.
Read full 
here :-https://www.bleepingcomputer.com/news/security/undocumented-commands-found-in-bluetooth-chip-used-by-a-billion-devices/