CVE-2024-0998
📋 TL;DR
A critical stack-based buffer overflow vulnerability exists in Totolink N200RE routers running firmware version 9.3.5u.6139_B20201216. Attackers can remotely exploit this by sending specially crafted requests to the setDiagnosisCfg function, potentially allowing arbitrary code execution. This affects all users of the vulnerable router firmware.
💻 Affected Systems
- Totolink N200RE
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote attackers gain full control of the router, enabling them to intercept traffic, pivot to internal networks, install persistent malware, or brick the device.
Likely Case
Remote code execution leading to router compromise, network traffic interception, and potential lateral movement to connected devices.
If Mitigated
If properly segmented and firewalled, impact limited to router compromise without internal network access.
🎯 Exploit Status
Public exploit details available in disclosed references. The vulnerability is in a CGI endpoint with straightforward buffer overflow conditions.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available - vendor did not respond to disclosure
Restart Required: Yes
Instructions:
No official patch available. Consider replacing affected hardware or implementing workarounds.
🔧 Temporary Workarounds
Disable Web Administration Interface
linuxDisable the router's web interface to prevent remote exploitation of the vulnerable CGI endpoint.
Access router CLI via SSH/Telnet and disable web interface (specific commands vary by router configuration)
Network Segmentation and Firewalling
linuxIsolate the router from untrusted networks and restrict access to administration ports.
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
🧯 If You Can't Patch
- Immediately disconnect affected routers from internet-facing interfaces
- Replace Totolink N200RE routers with supported/patched alternatives
🔍 How to Verify
Check if Vulnerable:
Check router firmware version via web interface at http://router-ip/ or via SSH: cat /proc/versionCheck Version:
curl -s http://router-ip/ | grep -i firmware || ssh admin@router-ip 'cat /proc/version'Verify Fix Applied:
No fix available to verify. Verify workarounds by confirming web interface is inaccessible and firewall rules are active.📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to /cgi-bin/cstecgi.cgi with setDiagnosisCfg parameter
- Multiple failed buffer overflow attempts in system logs
Network Indicators:
- HTTP traffic to router port 80/443 with unusually long 'ip' parameter values
- Exploit pattern: POST with Content-Type: application/x-www-form-urlencoded and setDiagnosisCfg
SIEM Query:
source="router_logs" AND (uri_path="/cgi-bin/cstecgi.cgi" AND http_method="POST" AND form_data CONTAINS "setDiagnosisCfg")🔗 References
- https://jylsec.notion.site/TOTOLINK-N200RE-has-stack-buffer-overflow-vulnerability-in-setDiagnosisCfg-b2d36451543e4c6da063646721a24604?pvs=4
- https://vuldb.com/?ctiid.252267
- https://vuldb.com/?id.252267
- https://jylsec.notion.site/TOTOLINK-N200RE-has-stack-buffer-overflow-vulnerability-in-setDiagnosisCfg-b2d36451543e4c6da063646721a24604?pvs=4
- https://vuldb.com/?ctiid.252267
- https://vuldb.com/?id.252267
