Chinese spies did a version of this against Lockheed... They would phish lockheed/military folks with emails stating "Hey we met at 'military conference' here

Chinese spies did a version of this against Lockheed... They would phish lockheed/military folks with emails stating "Hey we met at 'military conference' here is my contact file - lets stay in touch" The file had malware which would trickle very slowly data out. it was discovered due to one user complaining about his machine being slow... then it was discovered that it was discovered and the chinese opened the fire-hose and the worms were flooding the 3-egress points to the internet Lockheed had at that time, until they could kill the connects and clean up the system. The other thing the chinese did was to infect 3rd party suppliers who were supposed to be air-gapped, so they infected machines at suppliers to go after any USB sticks that were used to transfer info and get the malware back to Lockheed systems via the USB transfer of info between contractors and lockheed... Which is basically how stuxnet managed to get its foothold.