CVE-2023-27021
📋 TL;DR
This vulnerability in Tenda AC10 routers allows attackers to cause denial of service or execute arbitrary code by exploiting a stack overflow in the firewall configuration function. It affects Tenda AC10 routers running specific vulnerable firmware versions. Attackers can exploit this remotely without authentication.
💻 Affected Systems
- Tenda AC10 router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with remote code execution, allowing attackers to take full control of the router, intercept network traffic, pivot to internal networks, or install persistent malware.
Likely Case
Denial of service causing router crashes and network disruption, potentially followed by remote code execution if attackers craft sophisticated payloads.
If Mitigated
Limited impact with proper network segmentation, firewall rules blocking external access to router management interfaces, and intrusion detection systems monitoring for exploitation attempts.
🎯 Exploit Status
Public proof-of-concept code exists in GitHub repositories. The vulnerability requires sending crafted HTTP requests to the router's web interface.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: No official vendor advisory found
Restart Required: No
Instructions:
1. Check Tenda's official website for firmware updates. 2. If available, download the latest firmware. 3. Log into router web interface. 4. Navigate to firmware upgrade section. 5. Upload and apply the new firmware. 6. Verify the version has been updated.
🔧 Temporary Workarounds
Disable remote management
allPrevent external access to the router's web management interface
Restrict management interface access
allConfigure firewall rules to only allow management access from trusted internal IP addresses
🧯 If You Can't Patch
- Segment the network to isolate the vulnerable router from critical systems
- Implement network monitoring and intrusion detection to alert on exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface: Login > System Status > Firmware Version. If version is US_AC10V4.0si_V16.03.10.13_cn, the device is vulnerable.Check Version:
No CLI command available. Must check via web interface at http://router_ip or via router's admin panel.Verify Fix Applied:
After updating firmware, verify the version has changed from the vulnerable version. Test by attempting to access the firewall configuration page with normal usage patterns.📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to /goform/SetFirewallCfg endpoint
- Multiple failed firewall configuration attempts
- Router crash/reboot logs
Network Indicators:
- Unusual traffic patterns to router management interface from external IPs
- HTTP requests with oversized or malformed parameters to firewall configuration endpoint
SIEM Query:
source="router_logs" AND (uri="/goform/SetFirewallCfg" OR message="firewall config" OR message="router crash")