updated - January 26, 2015 Monday EST
The majority of the credit card account numbers involved in a hack Thursday are reportedly being spread around underground markets Krebs On Security reported Friday.
Forty million credit and debit account numbers were taken from Target customers between Nov. 27, and Dec. 15, and are now reportedly being used on new plastics Krebs On Security reported.
"This was obviously a very sophisticated crime," Molly Snyder, a Target spokeswoman told The Wall Street Journal Thursday.
The incident spanned the country in Target stores, and not online, and could have involved thieves fiddling with the machines customers utilize to slide their cards through while purchasing merchandise Bloomberg Businessweek reported.
An update from Target Friday said no pin information is believed to be obtained according to CNN Money. The security code on the cards plastic sticker near the card owner's signature on the underside of the card are also considered to be safe. The same is true for card user's social dates of birth, and social security number.
Target has supplied Visa, MasterCard, Discover, and American Express with the account numbers in question, who are currently watching out for any suspicious activity.
A bank in the U.S. New England states had 6,000 of the forty million account numbers affected according to Krebs On Security.
"Nobody has notified us," a source from a financial institution in New England told Krebs On Security. "Law enforcement hasn't said anything, our statewide banking associations haven't sent anything out, nothing. Our senior legal counsel today was asking me if we have positive confirmation from the card associations about affected cards, but so far we haven't gotten anything."
There are 1,797 Target stores in the United States. The retailer also has 124 in Canada.
"Target's first priority is preserving the trust of our guests and we have moved swiftly to address this issue, so guests can shop with confidence," Gregg Steinhafel, CEO at Target told Bloomberg Businessweek Thursday. "We take this matter very seriously and are working with law enforcement to bring those responsible to justice."
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