CVE-2023-49433
📋 TL;DR
Tenda AX9 routers running firmware V22.03.01.46 contain a stack overflow vulnerability in the SetVirtualServerCfg function. Attackers can exploit this by sending specially crafted requests to the '/goform/SetVirtualServerCfg' endpoint, potentially leading to remote code execution. This affects all users of vulnerable Tenda AX9 routers with this specific firmware version.
💻 Affected Systems
- Tenda AX9
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote unauthenticated attacker gains full control of the router, enabling traffic interception, network pivoting, and persistent backdoor installation.
Likely Case
Remote code execution leading to router compromise, allowing attackers to modify network settings, intercept traffic, or use the device for further attacks.
If Mitigated
If properly segmented and firewalled, impact limited to the router itself without lateral movement to other network devices.
🎯 Exploit Status
Public proof-of-concept available on GitHub. Exploitation requires sending crafted HTTP POST request to vulnerable endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not available
Restart Required: No
Instructions:
1. Check Tenda website for firmware updates
2. If update available, download and install via router web interface
3. Reboot router after update
4. Verify firmware version is no longer V22.03.01.46
🔧 Temporary Workarounds
Disable remote administration
allPrevent external access to router web interface
Access router settings > System > Remote Management > Disable
Block vulnerable endpoint
linuxUse firewall rules to block access to /goform/SetVirtualServerCfg
iptables -A INPUT -p tcp --dport 80 -m string --string "/goform/SetVirtualServerCfg" --algo bm -j DROP
🧯 If You Can't Patch
- Segment router on isolated network VLAN
- Implement strict firewall rules limiting router management interface access
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface: Login > System > Firmware UpgradeCheck Version:
curl -s http://router-ip/goform/getStatus | grep versionVerify Fix Applied:
Verify firmware version is no longer V22.03.01.46📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to /goform/SetVirtualServerCfg with abnormal parameter length
- Router crash/restart logs
Network Indicators:
- Unusual traffic patterns from router
- Outbound connections from router to suspicious IPs
SIEM Query:
source="router_logs" AND uri_path="/goform/SetVirtualServerCfg" AND http_method="POST"