“0x19790509. If it found the string, Stuxnet withdrew from the machine and wouldn’t infect it. Chien had seen “inoculation values” like this before. Hackers would place them in the registry key of their own computers so that after unleashing attack code in a test environment or in the wild, it wouldn’t come back to bite them by infecting their own machine or any other computers they wanted to protect. Inoculation values could be anything a hacker chose. Generally, they were just random strings of numbers.”