CVE-2009-5156
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary commands on ASMAX AR-804gu devices via command injection in the cgi-bin/script query string. Attackers can gain complete control of affected devices without authentication. Only ASMAX AR-804gu devices running firmware version 66.34.1 are affected.
💻 Affected Systems
- ASMAX AR-804gu
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing attackers to install persistent backdoors, intercept network traffic, pivot to internal networks, or use the device for botnet participation.
Likely Case
Remote code execution leading to device takeover, credential harvesting, and network reconnaissance from the compromised router.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation prevents lateral movement.
🎯 Exploit Status
Exploitation requires sending specially crafted HTTP requests to the vulnerable CGI endpoint. No authentication is required.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: No vendor advisory found
Restart Required: No
Instructions:
No official patch available. Consider replacing affected devices with supported models or implementing strict network controls.
🔧 Temporary Workarounds
Disable web interface access
linuxBlock external access to the router's web management interface
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
Network segmentation
allIsolate affected routers in separate VLANs with strict firewall rules
🧯 If You Can't Patch
- Replace affected devices with supported models that receive security updates
- Implement strict network segmentation and firewall rules to limit device exposure
🔍 How to Verify
Check if Vulnerable:
Check if device is ASMAX AR-804gu running firmware 66.34.1 via web interface or serial consoleCheck Version:
Check web interface status page or use serial console to view firmware versionVerify Fix Applied:
Verify device has been replaced or web interface access is properly restricted📡 Detection & Monitoring
Log Indicators:
- Unusual CGI script access patterns
- Multiple failed login attempts followed by script execution
- Commands like 'cat /etc/passwd' or 'wget' in URL parameters
Network Indicators:
- HTTP requests to /cgi-bin/script with shell metacharacters in parameters
- Outbound connections from router to suspicious IPs
SIEM Query:
source="router_logs" AND (uri="/cgi-bin/script" AND (param="|*" OR param=";*" OR param="&*"))