The Secret Service is investigating a massive security breach at Target stores nationwide, that might involve millions of credit and debit card transactions and the worst part is that it could take months for shoppers to learn if they are a victim.
Shoppers in San Francisco didn't leave the Target store on Geary with a warm feeling after hearing about the massive security breach, knowing they had used a credit card at Target.
"It's scary. This is the first time I've heard of that and I'm curious to [know] how that even happened in the first place," said San Francisco resident Tala Banatao.
No one is saying for sure, but experts believe hackers broke into Target's computer network, stealing data collected when customers swipe the magnetic strip on the back of their debit and credit cards.
Computer security expert Brian Krebs broke the story and says data was stolen from Black Friday -- a heavy shopping day -- until this past Sunday. It did not affect online sales at Target.
"It lets them take that information and encode it onto a new card and essentially duplicate that card and use it as if it were their credit card at any store," said Krebs.
It's unknown if debit card pin numbers were breached which would allow crooks to drain cash directly from ATMs.
However, it could take months for Target shoppers to learn if they are victims.
"You can as a cardholder are not liable for these charges, but there's a catch. You have to report it. You have to say, 'I didn't make these transactions' and if you're not paying attention to your statements, you may miss that," said Krebs.
Some shoppers are thinking twice about using plastic.
"Probably cash now. I do have cash to pay for what I need tonight," said Banatao.
Target has not responded to our request for a comment.
Target has 1,797 stores in the U.S. and 124 in Canada.
The company has set up a phone number to help customers who think they may be a victim - you can call (866) 852-8680.