The center says that more than 79 million records were reported compromised in the United States through Dec. 18. That is a nearly fourfold increase from the nearly 20 million records reported in 2006.
Another group, Attrition.org, estimates that worldwide more than 162 million records were compromised through Dec. 21. Attrition reported 49 million last year.
"It's just the nature of business, that moving forward, more companies are going to have more records, so there will be more records compromised each year," said Attrition's Brian Martin.
But the biggest difference between the groups' record-loss counts is Attrition.org's estimate that 94 million records were exposed in a theft of credit card data at Framingham-based TJX Cos., the owner of discount stores including T.J. Maxx and Marshalls. The TJX breach accounts for more than half the total records reported lost this year on both groups' lists.
The Identity Theft Resource Center counts about 46 million, the number of records TJX acknowledged in March were potentially compromised. Attrition's figure is based on estimates from Visa and MasterCard officials who were deposed in a lawsuit filed against TJX.
The breach is believed to have started when hackers intercepted wireless transfers of customer information at two Marshalls stores in Miami, an entry point that led the hackers to eventually break into TJX's central databases.
TJX has said that before the breach, which was disclosed in January, the company invested "millions of dollars on computer security and believes our security was comparable to many major retailers."
With wireless data transmission more common, hackers are expected to increasingly target what many specialists see as a major vulnerability. Eavesdroppers appear to be learning how to bypass security safeguards faster than ever, said Jay Tumas, the head of Harvard University's network operations, at a recent conference for information security professionals.
