CVE-2021-1297
📋 TL;DR
This vulnerability allows unauthenticated remote attackers to conduct directory traversal attacks and overwrite restricted files on affected Cisco Small Business VPN routers. Attackers can exploit insufficient input validation in the web-based management interface to upload files to unauthorized locations. Organizations using Cisco RV160, RV160W, RV260, RV260P, or RV260W VPN routers are affected.
💻 Affected Systems
- Cisco RV160 VPN Router
- Cisco RV160W VPN Router
- Cisco RV260 VPN Router
- Cisco RV260P VPN Router
- Cisco RV260W VPN Router
📦 What is this software?
Rv160w Wireless Ac Vpn Router Firmware by Cisco
View all CVEs affecting Rv160w Wireless Ac Vpn Router Firmware →
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to overwrite critical system files, install persistent backdoors, or brick the device.
Likely Case
Attackers overwrite configuration files to gain administrative access, redirect traffic, or disable security features.
If Mitigated
Limited impact if web management interface is disabled or restricted to internal networks only.
🎯 Exploit Status
Exploitation requires sending specially crafted HTTP requests to the web interface. No authentication required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.01.02 or later
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-rv160-260-filewrite-7x9mnKjn
Restart Required: Yes
Instructions:
1. Log into Cisco Software Center. 2. Download firmware version 1.0.01.02 or later for your specific model. 3. Access router web interface. 4. Navigate to Administration > Firmware Upgrade. 5. Upload and install the new firmware. 6. Reboot the router.
🔧 Temporary Workarounds
Disable Web Management Interface
allDisable the web-based management interface to prevent exploitation.
Access router CLI via SSH/Telnet
configure terminal
no ip http server
no ip http secure-server
end
write memory
Restrict Web Interface Access
allLimit web interface access to specific trusted IP addresses only.
Access router CLI via SSH/Telnet
configure terminal
ip http access-class [ACL-NAME]
ip http secure-server access-class [ACL-NAME]
end
write memory
🧯 If You Can't Patch
- Disable the web-based management interface entirely and use CLI for management.
- Implement strict network segmentation to isolate affected routers from untrusted networks.
🔍 How to Verify
Check if Vulnerable:
Check current firmware version via web interface (System Summary) or CLI (show version). If version is earlier than 1.0.01.02, device is vulnerable.Check Version:
show version | include SoftwareVerify Fix Applied:
After patching, verify firmware version is 1.0.01.02 or later. Test file upload functionality to ensure proper input validation.📡 Detection & Monitoring
Log Indicators:
- Multiple failed file upload attempts
- Unusual file modification events in system logs
- HTTP requests with directory traversal patterns (../)
Network Indicators:
- HTTP POST requests to file upload endpoints with unusual parameters
- Traffic to router web interface from unexpected sources
SIEM Query:
source="router_logs" AND (event="file_upload" OR event="file_modify") AND (path="*../*" OR user="unauthenticated")