CVE-2020-14937
📋 TL;DR
This vulnerability in Contiki-NG's SNMP BER encoder/decoder allows attackers to read or write memory outside allocated buffer boundaries. It affects systems running Contiki-NG 4.4 through 4.5 with SNMP functionality enabled. Successful exploitation could lead to remote code execution or denial of service.
💻 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 system compromise, data exfiltration, or persistent backdoor installation.
Likely Case
Denial of service through application crashes or memory corruption, potentially leading to system instability.
If Mitigated
Limited impact with proper network segmentation and exploit mitigations like ASLR and stack canaries.
🎯 Exploit Status
Proof of concept available in GitHub issue. Exploitation requires SNMP access to vulnerable device.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 4.6 and later
Vendor Advisory: https://github.com/contiki-ng/contiki-ng/issues/1354
Restart Required: Yes
Instructions:
1. Update Contiki-NG to version 4.6 or later. 2. Rebuild and redeploy firmware. 3. Restart affected devices.
🔧 Temporary Workarounds
Disable SNMP
allRemove SNMP functionality from build configuration to eliminate attack surface
# In contiki-ng configuration, set: CONTIKI_WITH_SNMP=0
Network Segmentation
allRestrict SNMP access to trusted management networks only
# Use firewall rules to block SNMP (UDP 161) from untrusted networks
🧯 If You Can't Patch
- Implement strict network access controls to limit SNMP traffic to trusted sources only
- Deploy intrusion detection systems to monitor for SNMP exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check Contiki-NG version and verify SNMP is enabled in build configurationCheck Version:
# In Contiki-NG source directory: grep CONTIKI_VERSION Makefile.includeVerify Fix Applied:
Verify version is 4.6+ and test SNMP functionality for stability📡 Detection & Monitoring
Log Indicators:
- SNMP protocol errors
- Memory access violation logs
- Application crashes
Network Indicators:
- Unusual SNMP traffic patterns
- SNMP requests with malformed BER encoding
SIEM Query:
source="snmp" AND (event_type="error" OR event_type="crash")