CVE-2020-3331
📋 TL;DR
This critical vulnerability allows unauthenticated remote attackers to execute arbitrary code with root privileges on affected Cisco RV110W and RV215W VPN firewall/routers. Attackers can exploit it by sending specially crafted requests to the web management interface. Organizations using these devices with internet-facing management interfaces are at highest risk.
💻 Affected Systems
- Cisco RV110W Wireless-N VPN Firewall
- Cisco RV215W Wireless-N VPN Router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attacker to install persistent backdoors, intercept all network traffic, pivot to internal networks, and use device as botnet member.
Likely Case
Device takeover leading to credential theft, network surveillance, and lateral movement into connected systems.
If Mitigated
Limited impact if management interface is not internet-facing and network segmentation prevents access from compromised zones.
🎯 Exploit Status
Exploit code is publicly available and requires no authentication. Attackers can automate exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: RV110W: 1.2.2.8, RV215W: 1.5.2.1
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-code-exec-wH3BNFb
Restart Required: Yes
Instructions:
1. Download firmware from Cisco support portal. 2. Log into device web interface. 3. Navigate to Administration > Firmware Upgrade. 4. Upload new firmware file. 5. Wait for automatic reboot and verify new version.
🔧 Temporary Workarounds
Disable Internet-Facing Management
allRestrict web management interface access to internal networks only
Network Segmentation
allPlace affected devices in isolated network segments with strict firewall rules
🧯 If You Can't Patch
- Immediately disable web management interface or restrict to specific trusted IP addresses
- Implement network monitoring for exploit attempts and unusual traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface: Login > Status > Router > Firmware VersionCheck Version:
No CLI command - check via web interface or SNMP if configuredVerify Fix Applied:
Confirm firmware version is RV110W 1.2.2.8 or later, or RV215W 1.5.2.1 or later📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts followed by successful access
- Unusual POST requests to web management endpoints
- Configuration changes from unknown IPs
Network Indicators:
- HTTP requests with unusual payloads to management interface
- Outbound connections from device to suspicious IPs
- Sudden traffic pattern changes
SIEM Query:
source="cisco-router" AND (url="*/login.cgi*" OR url="*/apply.cgi*") AND (status=200 OR bytes>10000)