CVE-2021-1165
📋 TL;DR
This vulnerability allows authenticated attackers to execute arbitrary code as root or cause denial of service on affected Cisco Small Business routers. Attackers need valid administrator credentials to exploit these input validation flaws in the web management interface. Organizations using Cisco RV110W, RV130, RV130W, or RV215W routers are affected.
💻 Affected Systems
- Cisco RV110W
- Cisco RV130
- Cisco RV130W
- Cisco RV215W
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise with root-level arbitrary code execution, allowing attackers to install persistent malware, intercept all network traffic, or use the device as a pivot point into the network.
Likely Case
Device reboot causing temporary denial of service, or limited code execution if attackers have admin credentials but lack sophisticated exploitation skills.
If Mitigated
No impact if proper access controls prevent unauthorized administrative access to the web interface.
🎯 Exploit Status
Exploitation requires valid administrator credentials but involves simple HTTP request crafting once authenticated.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: None available
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-rv-overflow-WUnUgv4U
Restart Required: No
Instructions:
No official patch available. Follow workarounds and mitigation steps instead.
🔧 Temporary Workarounds
Disable Web Management Interface
allDisable the web-based management interface and use alternative management methods
Access router CLI via SSH/Telnet and disable HTTP/HTTPS services
Restrict Management Access
allLimit web interface access to specific trusted IP addresses only
Configure firewall rules to allow management access only from specific IP ranges
🧯 If You Can't Patch
- Replace affected devices with supported models that receive security updates
- Segment affected routers in isolated network zones to limit potential damage
🔍 How to Verify
Check if Vulnerable:
Check if device model is RV110W, RV130, RV130W, or RV215W and has web management interface enabledCheck Version:
show version (via CLI) or check web interface System Information pageVerify Fix Applied:
Verify web interface is disabled or access is restricted to trusted IPs only📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts followed by successful login and unusual HTTP requests
- Device reboot logs without scheduled maintenance
Network Indicators:
- Unusual outbound connections from router to external IPs
- HTTP requests with malformed parameters to management interface
SIEM Query:
source="router_logs" (event="authentication success" AND user="admin") AND (http_uri CONTAINS "/admin/" OR http_method="POST" with unusual parameters)