That is a real stretch. STUXNET was designed and targetted at a specific environment. It was much the same as if someone broke in the facility and uploaded the virus themselves. It was only transmitted because of a break-down in security procedures. The designers knew about this vulnerability. An unsecured device was used much as a network device to transmit the virus. Most secured environments do not allow that to happen. I've worked on secured development and production environments (in fact, I have one I work on now) and know absolutely that they are unhackable other than by using very sophisticated means that is generally outside the means of most people other than countries. Of course, a country could use people to break into the facilities, have the resources to study the security procedures and assess vulnerabilities, and hack the machines to obtain the information or damage the facility. It just is rare and that is what makes these environments secure - NOT INVULNERABLE.