Incorrect Access Control in TOTOLINK T6 Router

Executive Summary

This vulnerability is an incorrect access control issue in the setVpnPassCfg function of TOTOLINK T6 firmware version 4.1.5cu.748_B20211015. It allows unauthenticated attackers to bypass security measures by sending a specially crafted POST request to /cgi-bin/cstecgi.cgi, potentially weakening edge filtering protections.

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Detection Guidance

Detecting this vulnerability requires checking for unauthorized POST requests to /cgi-bin/cstecgi.cgi that attempt to modify VPN password configurations. Monitor network traffic for suspicious POST requests targeting this endpoint, especially those without proper authentication. Check server logs for repeated failed access attempts to this path.

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Impact Analysis

This vulnerability could allow attackers to gain unauthorized access to network configurations or bypass security controls. If exploited, it may enable attackers to weaken network defenses, intercept traffic, or gain control over the device without authentication.

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Compliance Impact

This vulnerability allows unauthenticated attackers to weaken edge filtering via crafted POST requests, which could lead to unauthorized access to sensitive data. Such unauthorized access may violate compliance requirements under GDPR (data protection) and HIPAA (health information privacy) by exposing personal or health-related data.

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Mitigation Strategies

Immediately update the TOTOLINK T6 firmware to the latest version if a patch is available. Block external access to the /cgi-bin/cstecgi.cgi endpoint via firewall rules. Disable unnecessary services and restrict access to administrative interfaces. Monitor logs for any signs of exploitation attempts.

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