CVE-2025-5000
📋 TL;DR
A critical command injection vulnerability in Linksys FGW3000 routers allows remote attackers to execute arbitrary commands via manipulated filename parameters in HTTP POST requests to the control panel. This affects Linksys FGW3000-AH and FGW3000-HK routers up to version 1.0.17.000000. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- Linksys FGW3000-AH
- Linksys FGW3000-HK
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise allowing persistent backdoor installation, credential theft, network pivoting, and botnet recruitment.
Likely Case
Remote code execution leading to device takeover, network surveillance, and lateral movement within the network.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation.
🎯 Exploit Status
Exploit details are publicly available on GitHub. The vulnerability requires no authentication and has simple exploitation vectors.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: https://www.linksys.com/
Restart Required: Yes
Instructions:
1. Check Linksys website for firmware updates
2. If update available, download and install via web interface
3. Reboot device after update
4. Verify version is above 1.0.17.000000
🔧 Temporary Workarounds
Network Access Control
allRestrict access to router web interface from untrusted networks
Firewall Rules
linuxBlock external access to port 80/443 on affected devices
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Isolate affected devices in separate VLAN with strict firewall rules
- Implement network monitoring for unusual HTTP POST requests to /cgi-bin/sysconf.cgi
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface at http://[router-ip]/ or via SSH if enabled. Version should be above 1.0.17.000000.Check Version:
curl -s http://[router-ip]/ | grep -i firmware || ssh admin@[router-ip] 'cat /etc/version'Verify Fix Applied:
Verify firmware version is above 1.0.17.000000 and test that HTTP POST requests with malicious filename parameters no longer execute commands.📡 Detection & Monitoring
Log Indicators:
- HTTP POST requests to /cgi-bin/sysconf.cgi with unusual filename parameters
- System logs showing unexpected command execution
Network Indicators:
- HTTP traffic to router on port 80/443 with POST requests containing shell metacharacters in parameters
SIEM Query:
source="router-logs" AND (url="/cgi-bin/sysconf.cgi" AND method="POST" AND (filename="*;*" OR filename="*|*" OR filename="*`*"))