CVE-2020-17438
📋 TL;DR
This vulnerability in uIP 1.0 allows attackers to write beyond allocated memory buffers by sending specially crafted fragmented IP packets. This can cause denial of service or potentially execute arbitrary code on affected systems. It impacts products using uIP 1.0, including Contiki 3.0 and various embedded/IoT devices.
💻 Affected Systems
- uIP
- Contiki
- various embedded/IoT devices using uIP
📦 What is this software?
Uip by Uip Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise and attacker persistence on vulnerable devices.
Likely Case
Denial of service causing device crashes or instability, disrupting operations of affected systems.
If Mitigated
Limited impact with proper network segmentation and packet filtering preventing exploitation attempts.
🎯 Exploit Status
Exploitation requires sending specially crafted IP packets; no authentication needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Contiki-NG (successor to Contiki 3.0) and updated uIP versions
Vendor Advisory: https://us-cert.cisa.gov/ics/advisories/icsa-20-343-01
Restart Required: Yes
Instructions:
1. Update to Contiki-NG or patched uIP version. 2. Recompile and redeploy firmware. 3. Restart affected devices.
🔧 Temporary Workarounds
Network filtering of fragmented packets
linuxBlock or drop fragmented IP packets at network perimeter
iptables -A INPUT -f -j DROP
Disable IP packet reassembly
allConfigure devices to drop fragmented packets if functionality not required
🧯 If You Can't Patch
- Segment affected devices on isolated networks with strict access controls
- Implement network monitoring for fragmented packet attacks and anomaly detection
🔍 How to Verify
Check if Vulnerable:
Check if device uses uIP 1.0 or Contiki 3.0; examine firmware version stringsCheck Version:
Check device documentation or firmware version stringsVerify Fix Applied:
Verify updated firmware version and test with fragmented packet handling📡 Detection & Monitoring
Log Indicators:
- Device crashes
- Memory corruption errors
- Unexpected reboots
Network Indicators:
- Unusual fragmented IP packets
- Packets with malformed IP headers
SIEM Query:
source_ip=* AND (ip_fragmented=true AND (ip_header_length>20 OR ip_offset>8191))