It seems the problem was not stolen credit card data, but a feature that allowed devkits testing with fake credit card numbers.
Obviously a custom Firmware called REBUG allowed any PS3 to access the dev network and enabeled unlimited downloads with that feature.
source: http://www.thesixthaxis.com/2011/04/26/modders-to-blame-for-psn-downtime/
“It appeared that there had even been demonstrations to thank Big Brother for raising the chocolate ration to twenty grams a week. And only yesterday, he reflected, it had been announced that the ration was to be reduced to twenty grams a week. Was it possible that they could swallow that, after only twenty-four hours? Yes, they swallowed it.”
- George Orwell, ‘1984’







