Wired.com reports: "Imagine if the F-35 Joint Strike Fighter could be effectively shut down by a foreign adversary with the flip of a switch? That's, in part, the the concern behind the Defense Advanced Research Project Agency's Trust in Integrated Circuits program, reports IEEE Spectrum, in a fascinating article that explores the underbelly of national security and globalization"
There were rumors of this technology being used in the first Gulf War. I read a small article in Time magazine that talked about a network virus that was inserted into a printer's firmware that shutdown the network.
Although, I later read that this might be a hoax. If it's true or not that doesn't matter because the concept is realistic. Here is a post that I found that talks about it.