LAS VEGAS (AP) — The hackers are a tight knit group, 10 or 11. They live in a Russian town, and have real jobs. But in their down time, the cybercriminals have spent the past seven months gathering a hoard of personal data, stealing 1.2 billion user names and passwords in a series of Internet heists affecting 420,000 websites, according to Alex Holden, Chief Information Security Officer for Hold Security, whose firm uncovered the breach.

The Russian hackers had been collecting databases of personal information for years, but Holden told The Associated Press Wednesday that in April the group began deploying a new online attack technique that quickly shot from computer system to computer system as unwitting infected users visited random websites.