According to the Wall Street Journal, using just seven passwords taken from Nortel executives, including that of their CEO, the hackers penetrated Nortel's systems at least as far back as 2000.
The hackers also embedded malicious spyware so deeply on some systems that it took years to realize the extensiveness of the problem, according documents reviewed by The Wall Street Journal. They "had access to everything," an investigator told the Journal. "They had plenty of time. All they had to do was figure out what they wanted."