CVE-2021-21280
📋 TL;DR
This vulnerability allows attackers to cause an out-of-bounds write in Contiki-NG IoT operating system when processing 6LoWPAN packets with extension header chains. This could lead to memory corruption, potential remote code execution, or denial of service. It affects all Contiki-NG versions prior to 4.6 running on IoT devices.
💻 Affected Systems
- Contiki-NG
📦 What is this software?
Contiki Ng by Contiki Ng
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, data exfiltration, or device becoming part of a botnet.
Likely Case
Denial of service causing device crashes or instability, potentially disrupting IoT network operations.
If Mitigated
Limited impact with proper network segmentation and monitoring, potentially only causing isolated device failures.
🎯 Exploit Status
Exploitation requires sending specially crafted 6LoWPAN packets to vulnerable devices.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.6
Vendor Advisory: https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-r768-hrhf-v592
Restart Required: Yes
Instructions:
1. Update Contiki-NG to version 4.6 or later. 2. Recompile and redeploy firmware to affected IoT devices. 3. Restart devices to apply the updated firmware.
🔧 Temporary Workarounds
Apply GitHub patch manually
allApply the specific patch from GitHub pull request #1409 to older Contiki-NG versions
git apply https://github.com/contiki-ng/contiki-ng/pull/1409.patch
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable IoT devices from untrusted networks
- Deploy network monitoring to detect and block malicious 6LoWPAN packets with unusual extension header chains
🔍 How to Verify
Check if Vulnerable:
Check Contiki-NG version on device - if version is less than 4.6 and uses 6LoWPAN, it is vulnerable.Check Version:
Check firmware version or compile-time version constants in Contiki-NG source codeVerify Fix Applied:
Verify Contiki-NG version is 4.6 or higher after update and test with 6LoWPAN packet fuzzing tools.📡 Detection & Monitoring
Log Indicators:
- Device crashes or reboots
- Memory corruption errors in system logs
- Unusual 6LoWPAN packet processing failures
Network Indicators:
- Unusually long 6LoWPAN extension header chains
- Malformed 6LoWPAN packets targeting IoT devices
SIEM Query:
source="iot-device" AND (event="crash" OR event="reboot") AND version<"4.6"