CVE-2021-47802
📋 TL;DR
This vulnerability allows remote attackers to download router configuration files without authentication on Tenda D151 and D301 routers. Attackers can retrieve admin credentials and other sensitive data by sending a request to the /goform/getimage endpoint. Users of these specific router models are affected.
💻 Affected Systems
- Tenda D151
- Tenda D301
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain full administrative access to the router, enabling them to reconfigure settings, intercept network traffic, or launch further attacks on connected devices.
Likely Case
Attackers steal admin credentials and compromise the router's security, potentially leading to unauthorized network access or data theft.
If Mitigated
If routers are not internet-facing and have strong network segmentation, impact is limited to internal attackers, reducing overall risk.
🎯 Exploit Status
Exploit code is publicly available on Exploit-DB, making it easy for attackers to use with minimal technical skill.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown specific version; check Tenda vendor updates
Vendor Advisory: https://www.tendacn.com/us/
Restart Required: Yes
Instructions:
1. Visit the Tenda support website. 2. Download the latest firmware for your router model. 3. Log into the router admin panel. 4. Navigate to firmware upgrade section. 5. Upload and apply the new firmware. 6. Reboot the router after update.
🔧 Temporary Workarounds
Block External Access
linuxPrevent internet access to the router's admin interface by disabling remote management or using firewall rules.
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
Change Admin Credentials
allImmediately change router admin passwords to reduce risk if credentials are exposed, though this does not fix the underlying vulnerability.
🧯 If You Can't Patch
- Isolate the router on a segmented network to limit exposure to internal threats.
- Monitor network traffic for unauthorized access attempts to the /goform/getimage endpoint.
🔍 How to Verify
Check if Vulnerable:
Send a GET request to http://[router-ip]/goform/getimage and check if it returns configuration data without authentication.Check Version:
Log into router admin panel and check firmware version in system settings, or use curl -s http://[router-ip]/ | grep -i versionVerify Fix Applied:
After patching, attempt the same request; it should return an error or require authentication.📡 Detection & Monitoring
Log Indicators:
- Unusual access logs showing requests to /goform/getimage from unauthorized IPs
Network Indicators:
- HTTP traffic to router IP on port 80/443 with GET /goform/getimage
SIEM Query:
source="router_logs" AND url="/goform/getimage" AND user="-"