He's been revealing the underground black markets where the Target hackers are allegedly selling the stolen credit cards. (Interestingly, one thing he discovered is that credit cards from non-U.S. banks are priced higher, from $23.62 per card to as high as $135 per card, he says.)
On top of that, he discovered evidence that two different banks - a small, community bank and a large, top-10 bank - have bought back their customers' stolen cards, he says.
Now he believes he's found the real life identity of a Ukraine man that has, Krebs alleges, been involved with various underground markets that sell stolen credit cards. He's even engaged in an online chat with the person, while also admitting that he has no idea if this particular guy "was involved in hacking Target," Krebs writes, adding, "but it's a good bet that he at least knows who was."
This is a somewhat dangerous game for the security blogger.
Earlier this year, a group of hackers planned to frame Krebs for a crime. They intended to buy heroine from the Silk Road black market, pay for it in bitcoin, mail it to Krebs home, and call the police and get Krebs busted.
Krebs, who monitors many hacker underground hangouts, got wind of the plot and contacted the police and FBI and set up a sting operation of their own.
We'll see if how he fairs on tracking down the Target hacker. But it sure makes for some interesting reading. Like a Hollywood crime drama.