Target Corporation (NYSE:TGT)’s massive credit card data breach affected more than 70 million customers over the holiday season. But who is really behind the nefarious act remains a mystery. Recently, cyber intelligence firm IntelCrawler said in a report that a 17-year old Russian teen, Sergey Tarasov, authored the “BlackPOS” malware. BlackPOS is the same malware that’s been used to steal credit card data at Target Corporation (NYSE:TGT), Neiman Marcus and many other U.S. retailers.

Target

Russians behind Target’s data breach?

Tarasov, who goes by the “ree4” username, is well-known in the hacking community and online forums. He reportedly sold the malware to more than 60 cyber criminals in Europe. IntelCrawler added that he has also written many other malicious tools such as “DDoS attacks training”, “Ree4 mail brute” and social network account hacking.

But the St. Petersburg-based kid denied any involvement in the data breach. And security experts such as Brian Krebs said that Tarasov has been misidentified. Then IntelCrawler backed off slightly. The firm released an updated report yesterday, saying that the code was written by another author, but Tarasov played a role in the breach. IntelCrawler said the real person behind the username “ree4” is Rinat Shibaev, who worked closely with Tarasov to develop the malicious code. The firm still believes that Sergey Tarasov is linked to the malware.

A new twist in Target’s case

In another development, South Texas police arrested two Mexican citizens in Target Corporation (NYSE:TGT)’s security breach case. Police say the account information stolen during the holiday season is being divided and sold regionally. McAllen Police Chief Victor Rodriguez has arrested 28-year-old Daniel Guardiola Dominguez and 27-year-old Mary Carmen Garcia, both from Monterrey, Mexico. Police said they used credit cards containing South Texas residents’ account information. Dominguez and Garcia purchased merchandise worth tens of thousands of dollars at retail chains in the area. They were arrested on Sunday, when trying to re-enter the U.S.

Target Corporation (NYSE:TGT) shares closed Friday at $60.24.