CVE-2021-21282
📋 TL;DR
CVE-2021-21282 is a buffer overflow vulnerability in Contiki-NG's RPL implementations when operating in source-routing mode. Attackers can exploit this by sending specially crafted input packets to potentially execute arbitrary code or cause denial of service. This affects IoT devices running Contiki-NG versions before 4.5.
💻 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, allowing attackers to take control of IoT devices, steal data, or pivot to other network resources.
Likely Case
Denial of service causing device crashes or instability, potentially disrupting IoT network operations and functionality.
If Mitigated
Limited impact with proper network segmentation and input validation controls in place, potentially preventing exploitation or containing damage.
🎯 Exploit Status
Exploitation requires sending specially crafted packets to vulnerable devices, but no public proof-of-concept has been released.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.5
Vendor Advisory: https://github.com/contiki-ng/contiki-ng/security/advisories/GHSA-6xf2-77gf-fgjx
Restart Required: Yes
Instructions:
1. Update Contiki-NG to version 4.5 or later. 2. Recompile and redeploy firmware to affected IoT devices. 3. Restart devices to apply the update.
🔧 Temporary Workarounds
Apply out-of-band patch
allApply the specific patch for this vulnerability without upgrading to version 4.5
git apply CVE-2021-21282.patch
Disable source-routing mode
allConfigure RPL implementations to not use source-routing mode if not required
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable IoT devices from critical networks
- Deploy network intrusion detection/prevention systems to monitor for and block malicious RPL packets
🔍 How to Verify
Check if Vulnerable:
Check Contiki-NG version and verify if RPL source-routing mode is enabled in configurationCheck Version:
Check firmware version or compile-time version constants in Contiki-NG source codeVerify Fix Applied:
Verify Contiki-NG version is 4.5 or later and test with packet fuzzing tools📡 Detection & Monitoring
Log Indicators:
- Device crashes, abnormal restarts, memory corruption errors in system logs
Network Indicators:
- Unusual RPL packet patterns, malformed source-routing packets, traffic spikes to IoT devices
SIEM Query:
source="iot-device-logs" AND (event_type="crash" OR event_type="memory_error")