CVE-2021-42141
📋 TL;DR
This vulnerability in Contiki-NG's tinyDTLS implementation allows an attacker to cause denial of service by exploiting inconsistent epoch numbers during DTLS handshakes. It affects systems using Contiki-NG with tinyDTLS for secure IoT communications. The high CVSS score indicates critical impact potential.
💻 Affected Systems
- Contiki-NG with tinyDTLS
📦 What is this software?
Tinydtls by Contiki Ng
⚠️ Risk & Real-World Impact
Worst Case
Complete service disruption of IoT devices using DTLS for secure communication, potentially affecting critical infrastructure or industrial control systems.
Likely Case
Targeted DoS attacks against vulnerable IoT devices, causing service interruptions and potential data loss in constrained environments.
If Mitigated
Limited impact with proper network segmentation and monitoring, though vulnerable devices remain at risk of disruption.
🎯 Exploit Status
Public exploit details available in security advisories, making exploitation straightforward for attackers
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 2018-08-30
Vendor Advisory: https://github.com/contiki-ng/tinydtls/issues/27
Restart Required: Yes
Instructions:
1. Update Contiki-NG to latest version
2. Rebuild and redeploy affected firmware
3. Verify tinyDTLS version is post-2018-08-30
🔧 Temporary Workarounds
Network Segmentation
allIsolate vulnerable IoT devices from untrusted networks
DTLS Session Monitoring
allMonitor for abnormal DTLS handshake patterns
🧯 If You Can't Patch
- Implement strict network access controls to limit exposure
- Deploy intrusion detection systems to monitor for DTLS handshake anomalies
🔍 How to Verify
Check if Vulnerable:
Check Contiki-NG version and tinyDTLS commit date; if using tinyDTLS from 2018-08-30 or earlier, vulnerableCheck Version:
Check Contiki-NG build configuration and tinyDTLS source commit historyVerify Fix Applied:
Verify Contiki-NG version is updated and tinyDTLS commit is post-2018-08-30📡 Detection & Monitoring
Log Indicators:
- Multiple failed DTLS handshakes
- Abnormal session termination
Network Indicators:
- Unusual DTLS packet sequences
- Repeated handshake attempts with inconsistent epoch numbers
SIEM Query:
dtls.handshake.failure OR dtls.session.abnormal🔗 References
- http://packetstormsecurity.com/files/176625/Contiki-NG-tinyDTLS-Denial-Of-Service.html
- https://github.com/contiki-ng/tinydtls/issues/27
- https://seclists.org/fulldisclosure/2024/Jan/14
- http://packetstormsecurity.com/files/176625/Contiki-NG-tinyDTLS-Denial-Of-Service.html
- http://seclists.org/fulldisclosure/2024/Jan/14
- https://github.com/contiki-ng/tinydtls/issues/27
- https://seclists.org/fulldisclosure/2024/Jan/14
