CVE-2021-1318
📋 TL;DR
This vulnerability allows authenticated remote attackers with administrator credentials to execute arbitrary commands with root privileges on affected Cisco Small Business routers. It affects multiple RV series routers due to improper input validation in the web management interface. Attackers can exploit this by sending crafted HTTP requests to gain full control of the device.
💻 Affected Systems
- Cisco Small Business RV016
- RV042
- RV042G
- RV082
- RV320
- RV325
📦 What is this software?
Rv016 Multi Wan Vpn Router Firmware by Cisco
View all CVEs affecting Rv016 Multi Wan Vpn Router Firmware →
Rv042 Dual Wan Vpn Router Firmware by Cisco
View all CVEs affecting Rv042 Dual Wan Vpn Router Firmware →
Rv042g Dual Gigabit Wan Vpn Router Firmware by Cisco
View all CVEs affecting Rv042g Dual Gigabit Wan Vpn Router Firmware →
Rv082 Dual Wan Vpn Router Firmware by Cisco
View all CVEs affecting Rv082 Dual Wan Vpn Router Firmware →
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of router with root access, allowing attackers to intercept/modify all network traffic, install persistent backdoors, pivot to internal networks, or render the device inoperable.
Likely Case
Attackers with stolen or default admin credentials gain full control of the router to monitor network traffic, steal credentials, or use as a foothold for further attacks.
If Mitigated
With strong unique admin credentials and network segmentation, impact is limited to the router itself without lateral movement.
🎯 Exploit Status
Exploitation requires admin credentials but is straightforward once credentials are obtained. Multiple proof-of-concept exploits are publicly available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: RV016: 4.2.3.14, RV042/RV042G: 4.2.3.14, RV082: 4.2.3.14, RV320/RV325: 1.5.1.11
Vendor Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-rv-command-inject-BY4c5zd
Restart Required: Yes
Instructions:
1. Log into router web interface as admin. 2. Navigate to Administration > Firmware Upgrade. 3. Download appropriate firmware from Cisco website. 4. Upload and install firmware. 5. Router will reboot automatically.
🔧 Temporary Workarounds
Disable web management interface
allDisable remote web-based management to prevent exploitation
Navigate to Administration > Management > Remote Management > Disable
Restrict management access
allLimit web management interface access to specific IP addresses
Navigate to Firewall > Access Rules > Add rule to restrict management port access
🧯 If You Can't Patch
- Change all admin passwords to strong, unique credentials
- Disable remote management and only allow local console access
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface: Status > Router > Firmware VersionCheck Version:
No CLI command - check via web interface at Status > RouterVerify Fix Applied:
Verify firmware version matches or exceeds patched versions listed in advisory📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to management interface
- Multiple failed login attempts followed by successful login
- Commands executed via web interface with unusual parameters
Network Indicators:
- HTTP traffic to router management port with unusual payloads
- Outbound connections from router to unexpected destinations
SIEM Query:
source="router_logs" AND (url="*/apply.cgi" OR url="*/userRpm/*") AND (method="POST") AND (status=200) AND (size>1000)