Why the attackers increased their firing power to reach their target at this point is unclear. Perhaps the two years they’d spent inside Natanz’s computers had merely made them reckless, overconfident. But the most likely explanation is that the earlier versions of Stuxnet had been delivered via an insider or someone with close access to the target machines. If Stuxnet’s creators had subsequently lost this access, they would’ve felt the need to ramp up the spreading power to improve their chances of reaching their target.
