Stack-Based Buffer Overflow in TOTOLINK X2000R Firmware

Executive Summary

This is a stack-based buffer overflow vulnerability in the TOTOLINK X2000R router firmware. It exists in the formIpv6Setup function specifically in the dhcp_dns handling. An attacker can send a specially crafted HTTP request with malicious input to the dhcp_dns2 parameter to trigger a buffer overflow. This can lead to arbitrary code execution on the device with the privileges of the running process.

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Detection Guidance

Detecting this vulnerability requires checking for vulnerable TOTOLINK X2000R devices with firmware TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327. Inspect HTTP traffic for malformed requests targeting the dhcp_dns2 parameter in authenticated sessions. Use network scanning tools like Nmap to identify affected devices by checking for open ports and firmware versions.

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Impact Analysis

If exploited, this vulnerability allows an attacker to execute arbitrary code on your TOTOLINK X2000R router. This could lead to complete device compromise, allowing the attacker to take control of your network traffic, steal sensitive information, or use your router as a pivot point to attack other devices on your network. The attacker needs authenticated HTTP access, which may be obtained through stolen credentials or other means.

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Compliance Impact

This vulnerability could lead to unauthorized access to personal or sensitive data processed or stored on the network, violating GDPR and HIPAA requirements for data protection and security. Organizations using this vulnerable router may face compliance violations, legal penalties, and reputational damage if exploited.

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Mitigation Strategies

Immediately update the firmware of TOTOLINK X2000R devices to a patched version if available. If no patch exists, restrict access to the device's web interface via network segmentation or firewall rules. Disable unnecessary services and monitor for suspicious HTTP requests targeting the dhcp_dns2 parameter.

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