IoT Bluetooth Security: A Practical Guide

TL;DR

This guide shows you how to find and fix common security problems in Internet of Things (IoT) devices that use Bluetooth. We’ll cover pairing issues, weak encryption, and ways to stop attackers from listening in.

1. Understanding the Risks

Bluetooth is convenient, but it can be a target for hackers. Common vulnerabilities include:

• Weak Pairing: Devices might use PINs that are easy to guess (like ‘0000’).
• Man-in-the-Middle Attacks: An attacker intercepts communication between your device and another Bluetooth gadget.
• Bluejacking/Bluesnarfing: Sending unwanted messages or stealing data.
• Eavesdropping: Attackers listening to your conversations or data transfer.

2. Scanning for Devices

First, you need to see what Bluetooth devices are around. Use a tool like bluetoothctl (Linux) or a mobile app like ‘Bluetooth Scanner’ (Android/iOS).

bluetoothctl scan on

This will list nearby devices with their MAC addresses and names. Note the MAC address of your IoT device.

3. Pairing Security Checks

1. PIN Code: Check if your device uses a simple PIN (0000, 1234). If it does, change it in the device’s settings.
2. Secure Simple Pairing (SSP): SSP is better than older methods. Look for confirmation numbers on both devices during pairing.
3. Out-of-Band (OOB) Authentication: This uses another channel to verify pairing, like NFC or a QR code. It’s the most secure method.

4. Encryption Strength

Bluetooth uses encryption to protect your data. There are different levels:

• WEP: Very old and weak – avoid if possible.
• WPA/WPA2: Better, but still has weaknesses.
• AES-CCM: The strongest encryption currently available for Bluetooth.

Unfortunately, you often can’t directly check the encryption level used by an IoT device without specialized tools and firmware access. However, look for devices that advertise support for AES-CCM.

5. Firmware Updates

1. Check Regularly: Manufacturers release updates to fix security flaws. Check your device’s app or website for new versions.
2. Automatic Updates: If possible, enable automatic firmware updates.

6. Reducing Attack Surface

• Disable Discovery Mode: When not pairing, turn off Bluetooth discovery to prevent others from finding your device.
• Limit Pairing Time: Only keep Bluetooth on when you need it.
• Remove Unused Devices: Delete paired devices you no longer use.

7. Monitoring for Suspicious Activity

Keep an eye out for unusual behaviour:

• Unexpected Pairing Requests: Be cautious of requests from unknown devices.
• Data Usage Spikes: If your device suddenly uses a lot more data, it could be compromised.

8. Using Bluetooth Low Energy (BLE) securely

If your IoT device uses BLE:

• Advertising Packets: Minimize the information broadcast in advertising packets. Avoid including sensitive data.
• Service Discovery: Securely implement service discovery to prevent unauthorized access.
• GATT Security: Use GATT security features like authentication and encryption.