Final answer:
A HMI can be infected by a portable device through an Operating System Exploit (OE), such as a vulnerability in the Windows operating system.
Step-by-step explanation:
A HMI (Human-Machine Interface) can be infected by a portable device through a type of malware called an Operating System Exploit (OE). There are different types of operating systems that can be infected, such as Windows, macOS, or Linux. For example, if a portable device is connected to a HMI running on the Windows operating system, it can transfer malware to the HMI through a vulnerability in the Windows OS.