10The term zero-day in the digital security world refers to vulnerabilities that are unknown to the manufacturer of the software, as opposed to known vulnerabilities that have been on record with the manufacturer for some time. The fact that Stuxnet 1.x employed no less than four zero-day Windows exploits strongly suggests it was developed by an agency with highly sophisticated resources. In other words, Stuxnet 1.x wasn’t made by amateurs. This is literally world-class hacking in action!