CVE-2021-1602
📋 TL;DR
This vulnerability allows unauthenticated remote attackers to execute arbitrary commands with root privileges on affected Cisco Small Business VPN routers. The flaw exists in the web management interface due to insufficient input validation. Organizations using Cisco RV160, RV160W, RV260, RV260P, or RV260W routers are affected.
💻 Affected Systems
- Cisco RV160
- Cisco RV160W
- Cisco RV260
- Cisco RV260P
- Cisco RV260W
📦 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, or render the device inoperable.
Likely Case
Attacker gains full control of the router to monitor/modify traffic, steal credentials, or use as foothold for lateral movement within the network.
If Mitigated
Limited impact if device is patched, isolated from internet, or has web interface disabled.
🎯 Exploit Status
Exploit requires sending crafted HTTP request to web interface. Only commands without parameters can be executed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.01.02 and later
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-rv-code-execution-9UVJr7k4
Restart Required: Yes
Instructions:
1. Log into router web interface. 2. Navigate to Administration > Firmware Upgrade. 3. Download firmware version 1.0.01.02 or later from Cisco website. 4. Upload and install firmware. 5. Router will reboot automatically.
🔧 Temporary Workarounds
Disable Web Management Interface
allDisable the vulnerable web interface to prevent exploitation
Configure via CLI: no ip http server
Configure via CLI: no ip http secure-server
Restrict Web Interface Access
allLimit access to web interface to trusted IP addresses only
Configure via web interface: Firewall > ACL > Add rule to restrict port 80/443 access
🧯 If You Can't Patch
- Disable web management interface entirely and use CLI for management
- Place router behind firewall with strict inbound rules blocking all external access to management ports
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface: Status > Router > Firmware Version. If version is below 1.0.01.02, device is vulnerable.Check Version:
show version (CLI) or check Status > Router in web interfaceVerify Fix Applied:
Verify firmware version is 1.0.01.02 or higher after patching. Test by attempting to access web interface from unauthorized IPs (should be blocked if workaround applied).📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP requests to web interface
- Multiple failed login attempts followed by successful command execution
- System logs showing unexpected command execution
Network Indicators:
- HTTP POST requests with command injection patterns to router management interface
- Unusual outbound connections from router to external IPs
SIEM Query:
source="router_logs" AND (http_uri="*;*" OR http_uri="*|*" OR http_uri="*`*" OR http_uri="*$(*")