CVE-2024-7332: Totolink CP450 Auth Bypass Vulnerability

CVE-2024-7332 Overview

A critical hardcoded credentials vulnerability has been identified in TOTOLINK CP450 firmware version 4.1.0cu.747_B20191224. The vulnerability exists within the Telnet Service component, specifically in the file /web_cste/cgi-bin/product.ini. This security flaw allows remote attackers to gain unauthorized access to affected devices by exploiting the use of hard-coded passwords embedded in the firmware.

Critical Impact

Remote attackers can leverage hard-coded credentials to gain complete unauthorized access to TOTOLINK CP450 devices, potentially compromising network infrastructure and enabling further attacks on connected systems.

Affected Products

• TOTOLINK CP450 Firmware version 4.1.0cu.747_B20191224
• TOTOLINK CP450 Hardware devices running affected firmware

Discovery Timeline

• August 1, 2024 - CVE-2024-7332 published to NVD
• August 9, 2024 - Last updated in NVD database

NOTE: The vendor was contacted early about this disclosure but did not respond in any way.

Technical Details for CVE-2024-7332

Vulnerability Analysis

This vulnerability represents a significant firmware security flaw categorized under CWE-259 (Use of Hard-coded Password) and CWE-798 (Use of Hard-coded Credentials). The TOTOLINK CP450 router contains embedded credentials within its firmware that cannot be changed by the device administrator. These hard-coded passwords provide a backdoor that allows any attacker with knowledge of the credentials to remotely access the device's Telnet service.

The vulnerability is particularly severe because it can be exploited remotely over the network without requiring any user interaction or prior authentication. An attacker can connect to the Telnet service and authenticate using the hard-coded credentials to gain elevated access to the device.

Root Cause

The root cause of this vulnerability is insecure firmware development practices where developers embedded static credentials directly into the firmware configuration file located at /web_cste/cgi-bin/product.ini. This approach violates fundamental security principles as hard-coded credentials cannot be rotated or changed by end users, making all devices running the affected firmware permanently vulnerable.

Attack Vector

The attack vector is network-based, targeting the Telnet Service exposed on TOTOLINK CP450 devices. An attacker can exploit this vulnerability by:

1. Scanning for exposed TOTOLINK CP450 devices on the network or internet
2. Connecting to the Telnet service on port 23
3. Authenticating using the hard-coded credentials found in the firmware
4. Gaining administrative access to the device
5. Modifying device configuration, intercepting network traffic, or pivoting to other network resources

The exploit details have been disclosed publicly, and technical information is available in the GitHub IoT Vulnerability Report. Due to the nature of hard-coded credentials, the vulnerability cannot be mitigated through configuration changes alone.

Detection Methods for CVE-2024-7332

Indicators of Compromise

• Unexpected Telnet connection attempts to TOTOLINK CP450 devices from external IP addresses
• Successful Telnet authentication events during unusual hours or from unrecognized sources
• Configuration changes on CP450 devices that were not authorized by administrators
• Evidence of credential extraction attempts targeting the /web_cste/cgi-bin/product.ini file

Detection Strategies

• Monitor network traffic for Telnet connections (TCP port 23) to TOTOLINK CP450 devices
• Implement intrusion detection rules to alert on repeated authentication attempts to embedded device Telnet services
• Review authentication logs on network devices for access patterns indicating compromise
• Deploy network segmentation monitoring to detect lateral movement from IoT devices

Monitoring Recommendations

• Configure SIEM alerts for Telnet service access to IoT/embedded devices on your network
• Establish baseline network behavior for TOTOLINK devices and alert on deviations
• Monitor for outbound connections from CP450 devices that may indicate command and control activity
• Regularly audit firmware versions across deployed TOTOLINK devices

How to Mitigate CVE-2024-7332

Immediate Actions Required

• Disable the Telnet service on affected TOTOLINK CP450 devices if the feature is not required
• Isolate affected devices on a separate network segment with strict access controls
• Implement firewall rules to block external access to Telnet (port 23) on vulnerable devices
• Monitor affected devices closely for signs of unauthorized access
• Consider replacing affected devices with alternatives from vendors with better security practices

Patch Information

At the time of disclosure, the vendor (TOTOLINK) was contacted but did not respond. No official patch is currently available for this vulnerability. Organizations should implement compensating controls and consider device replacement. For the latest information, refer to VulDB #273255 and the GitHub IoT Vulnerability Report.

Workarounds

• Completely disable the Telnet service on affected devices through administrative interface
• Deploy network access control lists (ACLs) to restrict Telnet access to trusted management IPs only
• Place vulnerable devices behind a VPN or jump host requiring authentication before network access
• Replace affected TOTOLINK CP450 devices with hardware from vendors that provide timely security updates

# Example firewall rule to block external Telnet access to TOTOLINK devices
# Replace 192.168.1.100 with your device IP
iptables -A INPUT -p tcp --dport 23 -d 192.168.1.100 -j DROP
iptables -A INPUT -p tcp --dport 23 -s 10.0.0.0/8 -d 192.168.1.100 -j ACCEPT