CHARLESTON, S.C. (AP) — Stolen files like the data from 3.6 million hacked South Carolina tax returns is quickly sold on the Internet black market and chances of finding whoever did it are slim, one of the world’s leading cyber security experts says.

“Credit card numbers themselves end up being sold in batches of 1,000, 10,000, 100,000 in online underground forums and just being passed around the world,” said Michael DuBose, former chief of the U.S. Justice Department’s computer crime section.

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