CVE-2020-24341
📋 TL;DR
This vulnerability in picoTCP and picoTCP-NG allows attackers to cause denial-of-service or leak sensitive information by sending specially crafted TCP packets. It affects systems using these embedded TCP/IP stacks through version 1.7.0. The vulnerability stems from improper validation of TCP packet lengths leading to out-of-bounds memory reads.
💻 Affected Systems
- picoTCP
- picoTCP-NG
📦 What is this software?
Picotcp by Altran
⚠️ Risk & Real-World Impact
Worst Case
Complete system crash or memory corruption leading to remote code execution, potentially compromising the entire device.
Likely Case
Denial-of-service causing device reboot or service disruption, with possible information disclosure from memory leaks.
If Mitigated
Limited impact with proper network segmentation and monitoring, though service disruption may still occur.
🎯 Exploit Status
Exploitation requires network access to TCP services using vulnerable picoTCP. The vulnerability is in the core TCP processing making it broadly exploitable.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Versions after 1.7.0
Vendor Advisory: https://us-cert.cisa.gov/ics/advisories/icsa-20-343-01
Restart Required: Yes
Instructions:
1. Identify systems using picoTCP/picoTCP-NG. 2. Update to version after 1.7.0. 3. Recompile applications with updated library. 4. Restart affected services or devices.
🔧 Temporary Workarounds
Network Segmentation
allIsolate affected devices from untrusted networks using firewalls or VLANs
TCP Filtering
linuxImplement network filtering to block malformed TCP packets
iptables -A INPUT -p tcp --tcp-flags ALL FIN,URG,PSH -j DROP
iptables -A INPUT -p tcp --tcp-flags ALL ALL -j DROP
🧯 If You Can't Patch
- Implement strict network access controls to limit exposure
- Monitor for abnormal TCP traffic patterns and system crashes
🔍 How to Verify
Check if Vulnerable:
Check application/library version strings for picoTCP/picoTCP-NG ≤1.7.0Check Version:
strings binary_or_library | grep -i picotcpVerify Fix Applied:
Verify picoTCP/picoTCP-NG version >1.7.0 is installed and in use📡 Detection & Monitoring
Log Indicators:
- System crashes/reboots
- Memory access violation logs
- Abnormal TCP connection attempts
Network Indicators:
- Malformed TCP packets with invalid lengths
- TCP packets with unusual flag combinations
SIEM Query:
source="network_traffic" tcp.flags=* AND (tcp.length<20 OR tcp.length>1460)