Relatively harmless to computers not involved in uranium enrichment.
When it infects a computer, it checks to see if that computer is connected to specific models of programmable logic controllers (PLCs) manufactured by Siemens. PLCs are how computers interact with and control industrial machinery like uranium centrifuges. The worm then alters the PLCs' programming, resulting in the centrifuges being spun too quickly and for too long, damaging or destroying the delicate equipment in the process. While this is happening, the PLCs tell the controller computer that everything is working fine, making it difficult to detect or diagnose what's going wrong until it's too late.
good points but i didn’t mean to allude to the actual virus Stuxnet but to it’s assumed method of communication to the not-web-connected Iranian nuclear program. it’s alleged that the virus was put on a usb drive and left in the facility for some unsuspecting employee to insert into a computer out of curiosity.