Incorrect Access Control in TOTOLINK T6 Firmware

Executive Summary

This vulnerability is an incorrect access control issue in the TOTOLINK T6 router firmware version 4.1.5cu.748_B20211015. It exists in the getStaticDhcpRules function, which improperly restricts access to static DHCP reservation rules. An unauthenticated attacker can exploit this by sending a specially crafted POST request to the vulnerable endpoint /cgi-bin/cstecgi.cgi to retrieve these rules.

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Detection Guidance

To detect this vulnerability, monitor network traffic for POST requests to /cgi-bin/cstecgi.cgi with parameters targeting the getStaticDhcpRules function. Check server logs for unauthorized access attempts or unusual POST requests.

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Impact Analysis

This vulnerability allows attackers to obtain static DHCP reservation rules without authentication. This could expose internal network configurations, including IP addresses assigned to specific devices, potentially aiding further attacks such as man-in-the-middle or targeted exploits against connected devices.

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Mitigation Strategies

Immediately update the TOTOLINK T6 firmware to the latest version. Disable remote access to the web interface if not required. Restrict access to /cgi-bin/cstecgi.cgi via firewall rules. Monitor for suspicious activity.

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