To security company Cylance, which first spotted Cleaver, the warning is a sign that the campaign is larger than first thought -- it emphasizes Iran's "determination and fixation" to breach and spy on crucial infrastructure. The nation's government denies any involvement, but it's hard to imagine the FBI letting the country off the hook quite so easily given accusations that Iran broke into US Navy computers last year. No matter who's responsible, it's evident that the US' most vital companies now have one more thing to worry about.

[Image credit: IIPA via Getty Images]