Yep, I worked in Windows Servicing at the time it came out, there were at least 4 separate completely unknown-at-the-time exploits in Stuxnet. They most likely

Yep, I worked in Windows Servicing at the time it came out, there were at least 4 separate completely unknown-at-the-time exploits in Stuxnet. They most likely stole the signing certs by dropping USB keys in an office park in Taiwan, all of the stolen certs were from companies which shared a particular parking lot