CVE-2024-6135
📋 TL;DR
This CVE describes a heap-based buffer overflow vulnerability in Zephyr RTOS Bluetooth Classic stack due to missing buffer length checks. Attackers can exploit this to execute arbitrary code or cause denial of service on affected devices. This affects systems running Zephyr RTOS with Bluetooth Classic functionality enabled.
💻 Affected Systems
- Zephyr RTOS
📦 What is this software?
Zephyr by Zephyrproject
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, data exfiltration, or persistent backdoor installation.
Likely Case
Denial of service through device crashes or reboots, potentially disrupting Bluetooth connectivity and device functionality.
If Mitigated
Limited impact with proper network segmentation and Bluetooth security controls, potentially only causing temporary service disruption.
🎯 Exploit Status
Exploitation requires Bluetooth proximity and knowledge of vulnerable devices. No authentication needed to trigger the vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v3.7.1
Vendor Advisory: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-xcr5-5g98-mchp
Restart Required: Yes
Instructions:
1. Update Zephyr RTOS to version 3.7.1 or later. 2. Rebuild and redeploy firmware to affected devices. 3. Verify Bluetooth Classic functionality is properly configured with security controls.
🔧 Temporary Workarounds
Disable Bluetooth Classic
allDisable BR/EDR (Bluetooth Classic) functionality if not required, using BLE-only mode.
CONFIG_BT_CLASSIC=n in prj.conf or Kconfig
Enable Bluetooth Security
allEnforce Bluetooth pairing and encryption to limit attack surface.
CONFIG_BT_SMP=y
CONFIG_BT_BONDING=y in prj.conf
🧯 If You Can't Patch
- Segment Bluetooth network - isolate vulnerable devices from critical systems
- Implement physical security controls to limit Bluetooth proximity access
🔍 How to Verify
Check if Vulnerable:
Check Zephyr version and Bluetooth Classic configuration: grep -r 'CONFIG_BT_CLASSIC' in build directory and check Zephyr version.Check Version:
Check Zephyr version in project configuration or build output: cat VERSION or check west manifestVerify Fix Applied:
Verify Zephyr version is 3.7.1 or later and review Bluetooth stack configuration for proper buffer handling.📡 Detection & Monitoring
Log Indicators:
- Bluetooth stack crashes
- Unexpected device reboots
- Memory corruption errors in system logs
Network Indicators:
- Unusual Bluetooth connection attempts
- Malformed Bluetooth packets
- Excessive Bluetooth traffic
SIEM Query:
Device logs: (event_category="bluetooth" AND (event_type="crash" OR event_type="error")) OR (process="zephyr" AND exit_code!=0)