CVE-2020-24336
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code or cause denial of service via buffer overflow in Contiki and Contiki-NG operating systems when NAT64 is enabled. The bug occurs when parsing DNS responses without proper length validation, affecting devices running these IoT/embedded operating systems.
💻 Affected Systems
- Contiki
- Contiki-NG
📦 What is this software?
Contiki by Contiki Os
Contiki Ng by Contiki Ng
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, device takeover, and potential lateral movement in IoT networks.
Likely Case
Denial of service causing device crashes and network disruption in IoT environments.
If Mitigated
Limited impact if NAT64 is disabled or network segmentation isolates vulnerable devices.
🎯 Exploit Status
Exploitation requires sending malicious DNS responses to vulnerable devices with NAT64 enabled.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Contiki-NG 4.6 and later, Contiki patches available in security updates
Vendor Advisory: https://us-cert.cisa.gov/ics/advisories/icsa-20-343-01
Restart Required: Yes
Instructions:
1. Update to Contiki-NG 4.6 or later. 2. Apply security patches for Contiki 3.0. 3. Recompile and redeploy firmware. 4. Restart affected devices.
🔧 Temporary Workarounds
Disable NAT64
allDisable NAT64 functionality in Contiki/Contiki-NG configuration
Modify project-conf.h: #define UIP_CONF_IPV6 0
Or disable NAT64 in build configuration
Network Segmentation
allIsolate devices with NAT64 enabled from untrusted networks
🧯 If You Can't Patch
- Disable NAT64 functionality in all device configurations
- Implement strict network filtering to block malicious DNS responses to affected devices
🔍 How to Verify
Check if Vulnerable:
Check if NAT64 is enabled and version is Contiki ≤3.0 or Contiki-NG ≤4.5Check Version:
Check firmware version in device logs or via administrative interfaceVerify Fix Applied:
Verify version is Contiki-NG ≥4.6 or patched Contiki version, and check that address length validation exists in ip64-dns64.c📡 Detection & Monitoring
Log Indicators:
- Device crashes
- Memory corruption errors
- DNS parsing failures
Network Indicators:
- Malformed DNS responses targeting NAT64 devices
- Unusual traffic to/from IoT devices on port 53
SIEM Query:
source="iot-device" AND (event="crash" OR event="buffer_overflow")