CVE-2020-15489
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary commands with root privileges on affected Wavlink routers by injecting shell metacharacters into CGI scripts. It affects Wavlink WL-WN530HG4 M30HG4.V5030.191116 devices. Attackers can gain complete control of the device without authentication.
💻 Affected Systems
- Wavlink WL-WN530HG4
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to install persistent backdoors, pivot to internal networks, intercept all traffic, or use device in botnets.
Likely Case
Remote code execution leading to device takeover, credential theft, network surveillance, and lateral movement opportunities.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
Public exploit details available in referenced GitLab repository. Exploitation requires sending crafted HTTP requests to vulnerable CGI endpoints.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not found
Restart Required: No
Instructions:
No official patch available. Check Wavlink website for firmware updates. If unavailable, implement workarounds or replace devices.
🔧 Temporary Workarounds
Disable Web Management Interface
linuxDisable the vulnerable web interface if remote management is not required.
Access router CLI via SSH/Telnet and disable web server: killall httpd or similar
Network Access Control
linuxRestrict access to router management interface using firewall rules.
iptables -A INPUT -p tcp --dport 80 -s TRUSTED_IP -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
🧯 If You Can't Patch
- Isolate affected devices in separate VLAN with strict firewall rules
- Monitor network traffic to/from device for unusual patterns or exploit attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface or CLI. Version M30HG4.V5030.191116 is vulnerable.Check Version:
Check web interface System Status page or use: cat /proc/versionVerify Fix Applied:
Verify firmware has been updated to a version later than M30HG4.V5030.191116.📡 Detection & Monitoring
Log Indicators:
- Unusual CGI script access patterns
- Shell command execution in web logs
- Failed authentication attempts to CGI endpoints
Network Indicators:
- HTTP requests to CGI scripts with shell metacharacters
- Unexpected outbound connections from router
SIEM Query:
source="router_logs" AND (uri="*.cgi" AND (content="|" OR content=";" OR content="`" OR content="$"))