CVE-2023-38823
📋 TL;DR
A buffer overflow vulnerability in Tenda router firmware allows remote attackers to execute arbitrary code via the formSetCfm function in the httpd service. This affects multiple Tenda router models including AC19, AC18, AC9, and AC6. Attackers can potentially gain full control of affected devices.
💻 Affected Systems
- Tenda AC19
- Tenda AC18
- Tenda AC9
- Tenda AC6
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attacker to install persistent malware, pivot to internal networks, intercept all network traffic, and use device as botnet node.
Likely Case
Remote code execution leading to device takeover, credential theft, and network surveillance.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
Public proof-of-concept code exists in GitHub repositories. Exploitation appears straightforward based on available information.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not found in provided references
Restart Required: Yes
Instructions:
1. Check Tenda official website for firmware updates. 2. Download latest firmware for your model. 3. Access router admin interface. 4. Navigate to firmware upgrade section. 5. Upload and apply new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Disable remote administration
allPrevent external access to router admin interface
Access router admin panel -> Advanced Settings -> Remote Management -> Disable
Network segmentation
allIsolate routers from critical internal networks
🧯 If You Can't Patch
- Place affected routers behind a firewall with strict inbound filtering
- Implement network monitoring for suspicious traffic to/from router management interface
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface and compare with affected versions listCheck Version:
Access router admin interface at 192.168.0.1 or 192.168.1.1 and check System Status or About pageVerify Fix Applied:
Verify firmware version has been updated to a version not listed in affected versions📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP requests to router management interface
- Multiple failed login attempts followed by successful access
- Unexpected process execution in router logs
Network Indicators:
- Unusual outbound connections from router
- Traffic to known malicious IPs from router
- Port scanning originating from router
SIEM Query:
source_ip=router_ip AND (http_uri CONTAINS "/goform/formSetCfm" OR http_status=200 AND user_agent="malicious")