modbus authentication

Modbus authentication is a critical security concern in industrial control systems, as highlighted by the ICSA-26-099-02 advisory for GPL750 Modbus Missing Authentication. This vulnerability affects GPL Odorizers GPL750 systems, where a low-privileged remote attacker can send Modbus packets to manipulate register values, potentially causing incorrect gas odorization. The advisory covers multiple controller families and firmware lines, with mitigation requiring updates to GPL750 software and the underlying Horner firmware stack, plus hardening access to the control network. This tag covers discussions on missing authentication in Modbus protocols, focusing on industrial cybersecurity and patch management for operational technology.