CVE-2020-3198
📋 TL;DR
This critical vulnerability allows unauthenticated remote attackers or authenticated local attackers to execute arbitrary code or cause denial of service on affected Cisco routers. It affects Cisco 809/829 Industrial ISRs and CGR1000 routers running vulnerable IOS software versions. Successful exploitation could lead to complete system compromise.
💻 Affected Systems
- Cisco 809 Industrial ISR
- Cisco 829 Industrial ISR
- Cisco CGR1000 Connected Grid Router
📦 What is this software?
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⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with persistent remote access, data exfiltration, and use as pivot point for lateral movement within the network.
Likely Case
Remote code execution leading to router compromise, configuration changes, traffic interception, or denial of service through system crashes.
If Mitigated
Limited impact through network segmentation and access controls, though vulnerable systems remain at risk of exploitation.
🎯 Exploit Status
CVSS 9.8 indicates trivial exploitation with high impact. While no public PoC is confirmed, such critical vulnerabilities often see rapid weaponization.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Refer to Cisco Security Advisory for specific fixed releases for each affected platform
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-iot-rce-xYRSeMNH
Restart Required: Yes
Instructions:
1. Review Cisco advisory for exact fixed versions for your hardware. 2. Download appropriate IOS image from Cisco. 3. Backup current configuration. 4. Upload new IOS image via TFTP/SCP. 5. Reload router to apply update. 6. Verify new version is running.
🔧 Temporary Workarounds
Access Control List Restriction
allImplement strict ACLs to limit access to affected routers from untrusted networks
access-list 101 deny ip any any
interface gigabitethernet0/0
ip access-group 101 in
Network Segmentation
allIsolate affected routers in separate VLANs with strict firewall rules
🧯 If You Can't Patch
- Immediately isolate affected routers from internet and untrusted networks using firewall rules
- Implement strict network segmentation and monitor for unusual traffic patterns or configuration changes
🔍 How to Verify
Check if Vulnerable:
Check IOS version with 'show version' command and compare against vulnerable versions in Cisco advisoryCheck Version:
show version | include Cisco IOSVerify Fix Applied:
After patching, run 'show version' to confirm running fixed IOS release📡 Detection & Monitoring
Log Indicators:
- Unexpected router reloads
- Configuration changes not initiated by administrators
- Memory allocation failures in logs
Network Indicators:
- Unusual traffic patterns to/from routers
- Unexpected connections to router management interfaces
- Traffic indicating exploit attempts
SIEM Query:
source="router_logs" AND (event_type="reload" OR event_type="memory_error" OR event_type="config_change")