Target hackers have more data than they can sell

Those who stole the data appear to be keeping a low profile on underground forums

What's the downside to successfully stealing 40 million credit card numbers from Target? Trying to sell the data.

There's a thriving economy among cybercriminals, some of whom specialize in stealing credit card numbers to others who figure out a way to profit. But it's also constrained by supply and demand.

Too many card numbers on the market inevitably drives the price of a set of details down. Card information, referred to in underground forums as "dumps," are often priced according to how recently the details were stolen, its likely spending limit and whether the hackers have captured a PIN for the card.

+ MORE ON NETWORK WORLD The worst data breaches of 2013 +

Prices can range from a few dollars up to US$100. Cybercriminals often advertise the kind of data they've captured from the card's magnetic stripe, which has three so-called "tracks," each containing data.

"Track 1" data contains a card number, the victim's name and the card's expiration data, and Track 2 data contains the card number and expiration data. The third track is rarely used.

"You can imagine that having a lot of stolen credit cards will not net the hackers, say $35 per card for all 40 million," said Alex Holden, who runs a cybercrime consultancy, Hold Security. "Even if the hackers are willing to sell cards for $1 a card, no one will buy the stolen goods in these amounts."

Target said attackers likely intercepted 40 million debit and credit card numbers between Nov. 27 to Dec. 15, 2013, one of the busiest shopping periods in the U.S. Target CEO Gregg Steinhafel said in an interview with CNBC on Sunday that malware was discovered on point-of-sale terminals.

How those terminals were infected is still a mystery. Computer security experts are keeping a close eye on underground forums where the data is traded, looking for clues as to who may be responsible.

So far, they haven't seen much.

"We have seen some comments by other hackers that would suggest that there was no sound exist strategy by the thieves," Holden said. "Right now, they are maybe laying low knowing that everyone is looking for them."

Send news tips and comments to jeremy_kirk@idg.com. Follow me on Twitter: @jeremy_kirk

From CSO: 7 security mistakes people make with their mobile device
Join the discussion
Be the first to comment on this article. Our Commenting Policies