CVE-2021-42142
📋 TL;DR
This vulnerability in Contiki-NG tinyDTLS allows remote attackers to cause denial of service and false-positive packet drops by sending DTLS packets with large epoch numbers early in the connection. It affects DTLS servers using vulnerable versions of tinyDTLS, potentially disrupting secure communication channels.
💻 Affected Systems
- Contiki-NG tinyDTLS
📦 What is this software?
Tinydtls by Contiki Ng
⚠️ Risk & Real-World Impact
Worst Case
Complete denial of service for DTLS services, disrupting secure communications and potentially causing cascading failures in dependent systems.
Likely Case
Service disruption causing packet drops and connection failures for DTLS-protected communications.
If Mitigated
Minimal impact with proper network segmentation and monitoring in place.
🎯 Exploit Status
The vulnerability is well-documented with public references, making exploitation straightforward for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Contiki-NG repository for fixes after commit 53a0d97
Vendor Advisory: https://github.com/contiki-ng/tinydtls/issues/24
Restart Required: Yes
Instructions:
1. Update Contiki-NG tinyDTLS to latest version. 2. Recompile affected applications. 3. Restart DTLS services.
🔧 Temporary Workarounds
Network filtering
allFilter or rate-limit DTLS traffic with large epoch numbers at network perimeter
🧯 If You Can't Patch
- Implement network segmentation to isolate DTLS servers
- Deploy intrusion detection systems to monitor for exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check Contiki-NG tinyDTLS version against commit 53a0d97 or earlierCheck Version:
Check git log or version information in Contiki-NG tinyDTLS sourceVerify Fix Applied:
Verify tinyDTLS is updated beyond commit 53a0d97 and test DTLS functionality📡 Detection & Monitoring
Log Indicators:
- Unusual DTLS connection failures
- Increased packet drop rates in DTLS logs
Network Indicators:
- DTLS packets with abnormally large epoch numbers
- Sudden drops in DTLS traffic
SIEM Query:
Search for DTLS protocol anomalies or connection resets from single sources