Authentication Bypass in Lantronix SLC8000 Series Firmware

Executive Summary

This vulnerability is an authentication bypass in Lantronix devices that allows unauthenticated attackers to generate valid session tokens for logged-in users. Tokens are created using the device model and current time, making them predictable. Attackers can bypass IP and User-Agent checks by crafting a specific URI that exploits file extension handling in the web server.

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Detection Guidance

Detecting this vulnerability requires checking for unauthorized access attempts or unusual session activity in the web management portal of affected Lantronix devices. Monitor logs for repeated failed login attempts or unexpected session token usage. Since tokens are derived from device model and time, inspect network traffic for crafted URIs exploiting file extension handling. Use network scanning tools to identify vulnerable devices by checking firmware versions.

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Impact Analysis

An attacker could gain elevated privileges on the device, bypass security controls, and potentially access or control downstream serial-attached devices. This could lead to unauthorized configuration changes, data theft, or disruption of connected systems.

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Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating confidentiality requirements in GDPR and HIPAA. Organizations may fail compliance audits if they cannot demonstrate adequate protection against such attacks.

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Mitigation Strategies

Immediately isolate affected devices from untrusted networks. Disable the web management portal if not essential. Apply firmware updates from Lantronix if available. Implement network-level access controls to restrict access to the management interface. Monitor for suspicious activity and revoke any unauthorized sessions.

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