CVE-2024-8408
📋 TL;DR
A critical stack-based buffer overflow vulnerability in Linksys WRT54G routers allows remote attackers to execute arbitrary code by sending specially crafted POST requests to the /apply.cgi endpoint. This affects the validate_services_port function when manipulating the services_array parameter. Anyone using the vulnerable firmware version is at risk of complete device compromise.
💻 Affected Systems
- Linksys WRT54G
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to full router compromise, persistence installation, network traffic interception, and lateral movement to connected devices.
Likely Case
Router takeover enabling DNS hijacking, credential theft from network traffic, and botnet recruitment.
If Mitigated
Limited impact if device is behind firewall with restricted WAN access, though LAN exploitation remains possible.
🎯 Exploit Status
Exploit code is publicly available on GitHub. No authentication is required to trigger the vulnerability via POST request to /apply.cgi.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: None
Vendor Advisory: https://www.linksys.com/
Restart Required: No
Instructions:
No official patch exists. Vendor did not respond to disclosure. Consider replacing device or implementing workarounds.
🔧 Temporary Workarounds
Disable Web Administration Interface
allTurn off the web management interface to prevent remote exploitation
Access router CLI via telnet/SSH
Navigate to administration settings
Disable remote management/web interface
Restrict Access with Firewall Rules
linuxBlock external access to router web interface (port 80/tcp)
iptables -A INPUT -p tcp --dport 80 -j DROP
ufw deny 80/tcp
🧯 If You Can't Patch
- Replace the WRT54G with a supported router model that receives security updates
- Isolate the router on a dedicated VLAN with strict network segmentation to limit potential damage
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface at http://router-ip/ or via command: cat /proc/versionCheck Version:
curl -s http://router-ip/ | grep -i 'firmware version' || telnet router-ip 80Verify Fix Applied:
Verify web interface is disabled or inaccessible, and firmware version is changed if replacement occurs📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /apply.cgi with large services_array parameters
- Multiple failed buffer overflow attempts in web server logs
- Sudden router configuration changes without administrator action
Network Indicators:
- Abnormal outbound connections from router IP
- DNS queries to suspicious domains from router
- Port scanning originating from router
SIEM Query:
source="router.log" AND (url="/apply.cgi" OR method="POST") AND (services_array OR buffer_overflow)