Hidden Bluetooth Commands in ESP32 Chips Pose Serious Security Risks
A major vulnerability that affects over a billion devices worldwide
Why It’s Important
The ESP32 microchip, a widely used component in Internet of Things (IoT) devices, has been found to contain undocumented Bluetooth commands that could be exploited for malicious purposes. Manufactured by the Chinese company Espressif, these chips are used in over a billion devices globally. These vulnerabilities could allow attackers to impersonate trusted devices, access sensitive data, and even maintain persistent control over targeted systems. Given the massive adoption of ESP32 chips in smart locks, medical equipment, computers, and mobile devices, the security implications are far-reaching.
What It Is / How It Works
Spanish cybersecurity researchers from Tarlogic Security recently uncovered 29 undocumented commands in the ESP32 Bluetooth firmware. These hidden vendor-specific commands, tracked under CVE-2025-27840, provide low-level control over Bluetooth functions, including:
Device Impersonation: Spoofing trusted MAC addresses to deceive connected devices.
Memory Manipulation: Reading and writing to RAM and Flash memory without authorization.
LMP/LLCP Packet Injection: Executing advanced Bluetooth attacks that bypass standard security measures.
The researchers developed a custom C-based USB Bluetooth driver that enables direct access to Bluetooth traffic without relying on OS-specific APIs. This tool helped uncover these commands, which had not been publicly documented by the chip manufacturer, Espressif.
How to Mitigate It
While Espressif has yet to release an official statement, device manufacturers and developers can take several steps to mitigate the risks:
Firmware Updates: Monitor Espressif's official channels for security patches and apply updates as soon as they are available.
Bluetooth Security Best Practices: Implement stronger Bluetooth pairing and authentication mechanisms to reduce the risk of spoofing and unauthorized connections.
Network Segmentation: Isolate ESP32-powered IoT devices on separate network segments to prevent lateral movement by attackers.
Physical Security Measures: Restrict physical access to USB or UART interfaces, which could be used to exploit the undocumented commands.
Enhanced Code Audits: Developers using ESP32 chips should perform in-depth security assessments of Bluetooth implementations to detect and mitigate hidden risks.
How to Configure and Use Securely
Developers working with ESP32 chips should:
Disable unused Bluetooth features to minimize the attack surface.
Use secure boot and flash encryption to prevent unauthorized firmware modifications.
Monitor device logs for unusual Bluetooth activity, which could indicate exploitation attempts.
Notable Strengths of ESP32
One of the standout features of ESP32 chips is their flexibility in wireless connectivity, offering both Wi-Fi and Bluetooth in a cost-effective package. This dual capability makes them a popular choice for IoT developers, but security enhancements are needed to ensure they remain a safe option.
Stay Ahead of Emerging Threats
As IoT adoption grows, security vulnerabilities in commonly used hardware like the ESP32 can have widespread consequences. If you’re using devices with this chip, stay updated on security developments and apply mitigations to reduce your risk.
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