HMI

What is HMI?

HMI (Human-Machine Interface) is a device or software that serves as the point of contact between an operator and an industrial automation system. The HMI presents process data in graphical form - process diagrams, trend charts, alarms - and allows the operator to control the process by issuing commands.

HMI can take various forms: from a simple touchscreen panel mounted directly on a machine, through a dedicated operator workstation in a control room, to a web application accessible via a browser. Modern HMI systems often offer remote access, which simplifies management but also expands the attack surface.

HMI design is a separate engineering discipline. A well-designed interface helps the operator quickly understand the state of the process and make the right decisions, particularly in emergency situations. A poorly designed HMI can lead to operator errors with serious consequences.

Why does it matter?

HMI is the most common target in attacks on industrial systems, as it provides a convenient entry point - it often runs on a standard Windows operating system and is connected to both the corporate network and the control network. Compromising an HMI gives the attacker the ability to manipulate displayed data or issue false commands.

Securing HMI involves: updating operating systems, disabling unnecessary services, authenticating operators, logging actions and limiting remote access to the essential minimum using encrypted VPN connections.

Related topics

• SCADA
• PLC
• DCS
• OT security