alt Hacker News> In all fairness, the people who are experts in the field of Siemens PLC programming are usually mechanical-ish engineers and security is not in their skill set or on their mind.
Stuxnet was over a decade ago.
There should be a simple rule that everyone with the ability to understand things like PLCs should be able to grasp: your equipment does not touch the internet or external storage, period.
Those who can't grasp this concept should be shown the door with a recommendation that they find a less mentally-taxing line of work.
The Stuxnet PLCs weren't touching either, though.
The worm was designed to jump across network air gaps via USB flash drives, and spread across isolated networks to other hosts. Finally, it targeted what was likely going to be a service technician laptop, which had to connect to the PLC via a data cable to update and adjust its configuration.
An attack like this can only be avoided if you never transfer any data from the outside to the inside. But that means you won't ever be able to install any form of software update or upload new config files without manually typing them in - or even reinstall the OS on any machine...