How Did "Soupnazi" Allegedly Steal 130 Million Credit Card Numbers?

A 28-year-old hacker has been charged in what federal prosecutors are calling the largest case of identity theft ever seen. The man, Albert Gonzalez, worked with two unnamed Russian conspirators to run wild through the computer networks of a handful of prominent corporations, including 7-Eleven, the supermarket chain Hannaford Brothers, and the payment processor Heartland Payment Center. The size of the heist—130 million credit and debit card numbers, according to prosecutors—have many people wondering: How exactly is such a massive theft carried out? The Justice Department's indictment (pdf) describes how Gonzales (a.k.a. "segvec" and "soupnazi," among other aliases) and his co-conspirators pulled it off. They began the job by scanning lists of Fortune 500 companies for likely targets, and then visited retail outlets to scope out the payment systems used at checkout counters and to look for vulnerabilities.