CVE-2022-48113
📋 TL;DR
This vulnerability allows unauthenticated attackers to access the telnet service on TOTOLINK N200RE_v5 routers via a crafted POST request, then gain root access using hardcoded credentials. It affects users of specific TOTOLINK router firmware versions. The CVSS 9.8 score indicates critical severity.
💻 Affected Systems
- TOTOLINK N200RE_v5 router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the router with root access, enabling attackers to intercept all network traffic, install persistent malware, pivot to internal networks, or brick the device.
Likely Case
Attackers gain root access to the router, allowing them to monitor network traffic, modify DNS settings, or use the device as a foothold for further attacks.
If Mitigated
If telnet is disabled and proper network segmentation exists, impact is limited to denial of service if the router is accessible.
🎯 Exploit Status
Exploitation requires sending a crafted POST request to trigger telnet access, then using hardcoded credentials. Public blog posts detail the exploit methodology.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: Not found in provided references
Restart Required: No
Instructions:
Check TOTOLINK website for firmware updates. If available, download and flash the updated firmware following vendor instructions.
🔧 Temporary Workarounds
Disable telnet service
allPrevent telnet access by disabling the service through router administration interface
Block telnet port at firewall
linuxConfigure network firewall to block incoming connections to port 23 (telnet)
iptables -A INPUT -p tcp --dport 23 -j DROP
🧯 If You Can't Patch
- Isolate affected routers in a separate VLAN with strict access controls
- Implement network monitoring for telnet connection attempts and unusual POST requests
🔍 How to Verify
Check if Vulnerable:
Attempt to access telnet service on port 23 after sending a crafted POST request to the router's web interface, then try root login with hardcoded credentials.Check Version:
Check router web interface or use 'cat /proc/version' via SSH/telnet if accessibleVerify Fix Applied:
Verify telnet service is not accessible on port 23 and that the POST request no longer triggers telnet access.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to router web interface
- Telnet connection attempts from unexpected sources
- Root login attempts via telnet
Network Indicators:
- Telnet traffic (port 23) to routers
- Crafted HTTP POST requests to router management interfaces
SIEM Query:
source="router_logs" AND (event="POST_request" OR event="telnet_connection")