CVE-2021-21410
📋 TL;DR
CVE-2021-21410 is an out-of-bounds read vulnerability in Contiki-NG's 6LoWPAN packet processing that allows attackers to read beyond allocated memory boundaries. This affects IoT devices running Contiki-NG 4.6 and earlier when processing specially crafted compressed IPv6 packets. The vulnerability could lead to information disclosure or potentially enable further exploitation.
💻 Affected Systems
- Contiki-NG
📦 What is this software?
Contiki Ng by Contiki Ng
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution or device compromise through memory corruption leading to complete system takeover.
Likely Case
Information disclosure through memory reads, potential denial of service through crashes, or enabling further exploitation chains.
If Mitigated
Limited impact with proper network segmentation and monitoring, potentially just crashes or performance issues.
🎯 Exploit Status
Exploitation requires crafting specific 6LoWPAN packets but no authentication needed. No public exploit code known at time of advisory.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patch available via GitHub PR #1482, no official release with fix at time of advisory
Vendor Advisory: https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-hhwj-2p59-v8p9
Restart Required: Yes
Instructions:
1. Apply patch from GitHub PR #1482 manually. 2. Recompile Contiki-NG from source. 3. Deploy updated firmware to affected devices. 4. Restart devices to apply changes.
🔧 Temporary Workarounds
Apply GitHub patch manually
allManually apply the fix from GitHub pull request #1482 to your Contiki-NG source code
git clone https://github.com/contiki-ng/contiki-ng
cd contiki-ng
git fetch origin pull/1482/head:patch-1482
git checkout patch-1482
🧯 If You Can't Patch
- Segment IoT devices on isolated networks with strict firewall rules blocking unnecessary 6LoWPAN traffic
- Implement network monitoring for anomalous 6LoWPAN packet patterns and deploy IDS/IPS systems
🔍 How to Verify
Check if Vulnerable:
Check Contiki-NG version and verify if uncompress_hdr_iphc function lacks proper boundary checks in os/net/ipv6/uip6.cCheck Version:
Check Contiki-NG version in build configuration or device firmware versionVerify Fix Applied:
Verify patch from PR #1482 is applied by checking the uncompress_hdr_iphc function has proper buffer length validation📡 Detection & Monitoring
Log Indicators:
- Device crashes or restarts
- Memory access violation logs
- Abnormal 6LoWPAN packet processing errors
Network Indicators:
- Malformed 6LoWPAN packets with unusual compression patterns
- Traffic spikes to IoT devices on 6LoWPAN ports
SIEM Query:
source="iot-device" AND (event_type="crash" OR event_type="memory_error") OR dest_port IN (61616, 61617) AND packet_size < expected_min