CVE-2020-3465
📋 TL;DR
This vulnerability in Cisco IOS XE Software allows an unauthenticated attacker on the same network segment to cause a denial of service by sending specially crafted Ethernet frames that trigger a device reload. It affects Cisco devices running vulnerable IOS XE versions, potentially disrupting network operations.
💻 Affected Systems
- Cisco IOS XE Software
📦 What is this software?
Ios Xe by Cisco
Cisco IOS XE is Cisco's modern network operating system running on enterprise routers, switches, and wireless controllers deployed across corporate networks, data centers, branch offices, and service provider infrastructure worldwide. As the evolution of Cisco IOS, IOS XE provides a Linux-based modu...
Learn more about Ios Xe →Ios Xe by Cisco
Cisco IOS XE is Cisco's modern network operating system running on enterprise routers, switches, and wireless controllers deployed across corporate networks, data centers, branch offices, and service provider infrastructure worldwide. As the evolution of Cisco IOS, IOS XE provides a Linux-based modu...
Learn more about Ios Xe →⚠️ Risk & Real-World Impact
Worst Case
Complete network outage as multiple devices reload simultaneously, causing extended downtime and service disruption.
Likely Case
Individual device reloads causing temporary network interruptions and potential service degradation.
If Mitigated
Minimal impact with proper network segmentation and monitoring to detect and block malicious frames.
🎯 Exploit Status
Exploitation requires sending crafted Ethernet frames to vulnerable interface; no authentication needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Refer to Cisco advisory for specific fixed releases
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-le-drTOB625
Restart Required: Yes
Instructions:
1. Check current IOS XE version. 2. Review Cisco advisory for fixed releases. 3. Download and install appropriate fixed software version. 4. Reload device to apply update.
🔧 Temporary Workarounds
Network Segmentation
allIsolate vulnerable devices to trusted network segments to limit attack surface
Access Control Lists
allImplement ACLs to restrict traffic to vulnerable interfaces from untrusted sources
access-list 100 deny ip any any
interface gigabitethernet0/0
ip access-group 100 in
🧯 If You Can't Patch
- Implement strict network segmentation to isolate vulnerable devices
- Deploy network monitoring to detect and alert on unusual Ethernet frame patterns
🔍 How to Verify
Check if Vulnerable:
Check IOS XE version against affected versions in Cisco advisoryCheck Version:
show version | include IOS XEVerify Fix Applied:
Verify installed version matches or exceeds fixed releases listed in advisory📡 Detection & Monitoring
Log Indicators:
- Unexpected device reloads
- System crash logs
- Ethernet interface errors
Network Indicators:
- Unusual Ethernet frame patterns
- Bursts of malformed frames to device interfaces
SIEM Query:
source="network_device" AND (event_type="crash" OR event_type="reload")