David Canton has just posted a link to a very interesting and insightful article on the TJX/Winners breach, which sheds light on how the scammers were able to penetrate the TJX system to take approximately TWO HUNDRED MILLION credit card numbers.
How Credit-Card Data Went Out Wireless Door - WSJ.com
... When wireless data networks exploded in popularity starting around 2000, the data was largely shielded by a flawed encoding system called Wired Equivalent Privacy, or WEP, that was quickly pierced. The danger became evident as soon as 2001, when security experts issued warnings that they were able to crack the encryption systems of several major retailers.
By 2003, the wireless industry was offering a more secure system called Wi-Fi Protected Access or WPA, with more complex encryption. Many merchants beefed up their security, but others including TJX were slower to make the change. An auditor later found the company also failed to install firewalls and data encryption on many of its computers using the wireless network, and didn't properly install another layer of security software it had bought. The company declined to comment on its security measures.
The hackers in Minnesota took advantage starting in July 2005. Though their identities aren't known, their operation has the hallmarks of gangs made up of Romanian hackers and members of Russian organized crime groups that also are suspected in at least two other U.S. cases over the past two years, security experts say. Investigators say these gangs are known for scoping out the least secure targets and being methodical in their intrusions, in contrast with hacker groups known in the trade as "Bonnie and Clydes" who often enter and exit quickly and clumsily, sometimes strewing clues behind them.
The TJX hackers did leave some electronic footprints that show most of their break-ins were done during peak sales periods to capture lots of data, according to investigators. They first tapped into data transmitted by hand-held equipment that stores use to communicate price markdowns and to manage inventory. "It was as easy as breaking into a house through a side window that was wide open," according to one person familiar with TJX's internal probe. The devices communicate with computers in store cash registers as well as routers that transmit certain housekeeping data.
After they used that data to crack the encryption code the hackers digitally eavesdropped on employees logging into TJX's central database in Framingham and stole one or more user names and passwords, investigators believe. With that information, they set up their own accounts in the TJX system and collected transaction data including credit-card numbers into about 100 large files for their own access. They were able to go into the TJX system remotely from any computer on the Internet, probers say....