CVE-2024-7335
📋 TL;DR
A critical buffer overflow vulnerability in TOTOLINK EX200 routers allows remote attackers to execute arbitrary code by manipulating the http_host parameter in the getSaveConfig function. This affects TOTOLINK EX200 routers running firmware version 4.0.3c.7646_B20201211. Attackers can exploit this without authentication to potentially take full control of affected devices.
💻 Affected Systems
- TOTOLINK EX200
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete device compromise, creation of persistent backdoors, lateral movement to internal networks, and botnet recruitment.
Likely Case
Remote code execution allowing attackers to modify device configuration, intercept network traffic, or use the device as a pivot point for further attacks.
If Mitigated
Limited impact if devices are behind firewalls with strict inbound filtering and network segmentation prevents lateral movement.
🎯 Exploit Status
Public exploit code is available on GitHub. The vulnerability requires no authentication and has a straightforward exploitation path.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: Yes
Instructions:
No official patch is available. The vendor did not respond to disclosure. Consider replacing affected devices or implementing workarounds.
🔧 Temporary Workarounds
Block Access to Vulnerable Endpoint
linuxUse firewall rules to block access to the vulnerable CGI endpoint
iptables -A INPUT -p tcp --dport 80 -m string --string "/cgi-bin/cstecgi.cgi" --algo bm -j DROP
iptables -A INPUT -p tcp --dport 443 -m string --string "/cgi-bin/cstecgi.cgi" --algo bm -j DROP
Disable Remote Management
allDisable WAN-side access to the router's management interface
🧯 If You Can't Patch
- Isolate affected devices in a dedicated VLAN with strict firewall rules preventing outbound connections
- Implement network monitoring and intrusion detection specifically for buffer overflow attempts targeting the vulnerable endpoint
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface at 192.168.0.1 or using nmap: nmap -sV -p 80,443 <router_ip>Check Version:
curl -s http://192.168.0.1/ | grep -i version or check web interface at System Status > Firmware VersionVerify Fix Applied:
Test if the vulnerable endpoint still responds to buffer overflow attempts or verify firmware version has changed📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /cgi-bin/cstecgi.cgi with long http_host parameters
- Router reboot events or configuration changes not initiated by administrators
Network Indicators:
- Traffic patterns indicating buffer overflow attempts (repeated long strings in HTTP parameters)
- Unexpected outbound connections from router to external IPs
SIEM Query:
source="router_logs" AND uri="/cgi-bin/cstecgi.cgi" AND (http_host.length > 100 OR action="save")