CVE-2020-20657
📋 TL;DR
A buffer overflow vulnerability in fcovatti libiec_iccp_mod v1.5 allows attackers to cause denial of service by sending unexpected packets during connection attempts. This affects systems using this library for IEC 60870-5-104/TASE.2 protocol implementations in industrial control systems.
💻 Affected Systems
- fcovatti libiec_iccp_mod
📦 What is this software?
Libiec Iccp Mod by Libiec Iccp Mod Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise and potential manipulation of industrial control systems
Likely Case
Denial of service causing disruption to industrial communication and control operations
If Mitigated
Limited impact with proper network segmentation and monitoring in place
🎯 Exploit Status
The vulnerability requires sending malformed packets during connection attempts, which is relatively straightforward for attackers with network access
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: v1.6 or later
Vendor Advisory: https://github.com/fcovatti/libiec_iccp_mod/issues/1
Restart Required: Yes
Instructions:
1. Download latest version from GitHub repository 2. Replace vulnerable library files 3. Recompile applications using the library 4. Restart affected services
🔧 Temporary Workarounds
Network Segmentation
linuxIsolate systems using libiec_iccp_mod from untrusted networks
iptables -A INPUT -p tcp --dport 2404 -j DROP
iptables -A INPUT -s trusted_network -p tcp --dport 2404 -j ACCEPT
Rate Limiting
linuxLimit connection attempts to prevent exploitation
iptables -A INPUT -p tcp --dport 2404 -m state --state NEW -m recent --set
iptables -A INPUT -p tcp --dport 2404 -m state --state NEW -m recent --update --seconds 60 --hitcount 10 -j DROP
🧯 If You Can't Patch
- Implement strict network access controls allowing only trusted sources to communicate on port 2404
- Deploy intrusion detection systems to monitor for abnormal connection patterns and packet anomalies
🔍 How to Verify
Check if Vulnerable:
Check library version: ldd /path/to/application | grep libiec_iccp_mod and verify version is 1.5Check Version:
strings /usr/lib/libiec_iccp_mod.so | grep 'libiec_iccp_mod'Verify Fix Applied:
Verify library version is 1.6 or later and test connection handling with malformed packets📡 Detection & Monitoring
Log Indicators:
- Multiple failed connection attempts
- Application crashes or restarts
- Memory access violation errors
Network Indicators:
- Abnormal packet sizes during connection establishment
- Malformed IEC 60870-5-104 packets
- Rapid connection attempts from single source
SIEM Query:
source="network_logs" dest_port=2404 packet_size>1500 OR source="app_logs" message="*segmentation fault*" OR message="*buffer overflow*"