Bluetooth Security: LE 4.0 Risks & Fixes

G5 Cyber Security

2 weeks ago

TL;DR

Bluetooth Low Energy (LE) 4.0 is widely used, but has security weaknesses. This guide explains common risks – eavesdropping, man-in-the-middle attacks, and device spoofing – and how to protect yourself through pairing modes, connection management, and firmware updates.

Understanding the Risks

Bluetooth LE 4.0 was designed for low power consumption, which sometimes meant compromises in security compared to older Bluetooth versions. Here’s a breakdown of common threats:

Eavesdropping: Attackers can listen in on unencrypted communication between your device and another Bluetooth device.
Man-in-the-Middle (MITM) Attacks: An attacker intercepts the communication, potentially reading or altering data.
Device Spoofing: An attacker pretends to be a trusted device to gain access.

Improving Bluetooth Security – Step by Step

Pairing Mode Awareness
- Be cautious when pairing: Only pair with devices you trust and recognise. Avoid pairing in public places if possible.
- Understand Pairing Methods: Bluetooth LE uses different pairing methods, each with varying security levels:
  - Just Works: Simplest, least secure – no authentication. Avoid this when sensitive data is involved.
  - Numeric Comparison: Displays a code on both devices for verification. Good if you can visually confirm the codes match.
  - Passkey Entry: Requires entering a PIN on both devices. Most secure, but requires user interaction.
Connection Management
- Disable Bluetooth when not in use: Reduces the attack surface. On Android:
```
Settings > Connections > Bluetooth > Toggle off
```
  On iOS:
```
Settings > Bluetooth > Toggle off
```
- Limit device visibility: Some devices allow you to control how long they remain discoverable. Shorten this time if possible.
- Be wary of unsolicited connection requests: Don’t accept connections from unknown devices.
Firmware Updates
- Keep your device’s firmware up to date: Manufacturers often release updates that address security vulnerabilities. Check for updates regularly:
  - Android: Settings > About phone > Software update
  - iOS: Settings > General > Software Update
Device-Specific Security Features
- Check your device’s documentation: Some devices offer additional security features, such as encryption settings or MAC address filtering.
- Consider using a Bluetooth scanner app: These apps can help identify nearby Bluetooth devices and potential threats (though they are not foolproof).
Secure Coding Practices (for Developers)
- Use encryption: Always encrypt sensitive data transmitted over Bluetooth LE.
- Implement proper authentication: Verify the identity of connected devices before exchanging data.
- Regular security audits: Conduct regular security audits to identify and address potential vulnerabilities in your code.

Advanced Considerations

For more technical users:

LE Secure Connections (LES): LES uses Elliptic-Curve Diffie–Hellman Perfect Forward Secrecy (ECDH PFS) for key exchange, providing stronger security than older methods. Ensure your devices support and use LES.
Privacy Features: Bluetooth LE includes privacy features like resolvable private addresses (RPAs). Understand how these features work and configure them appropriately to protect your identity.