The key to your accounts - namely the information on the magnetic stripe - can be copied when you use your bankcard at gas stations, stores, or increasingly even at your own bank's ATM.
Gregory Antonsen of the New York Police says thieves do it by installing a device called a skimmer right over the real card reader.
"When you pass your ATM card in and withdraw it, that little chip in there records the information off your magnetic stripe."
To record your pin number, thieves often install a camera hidden in a panel above the keypad.
"The thieves can download your account information onto the magnetic stripe of a blank card, learn your pin number from the camera recording, and start draining your account of cash," Kim Kleman said.
That's what happened to Rose Flores when she used the ATM at her bank last year before going on vacation. When she got back she discovered thieves were raiding her bank account.
"I felt very violated and very scared. They took out almost 6,000."
Rose discovered the theft by checking her statements online. Chase eventually reimbursed all the money she lost, but she's very careful using atms now.
Important precautions - check the ATM to see if anything looks loose or out of place.
"If anything looks suspicious, don't use the ATM and contact the bank and the police right away," Kleman said.
Consumer Reports says when it comes to gas stations, skimmers on the pumps are nearly impossible to detect, so it advises paying with credit cards versus debit cards.
And even if a card reader looks legitimate, shield the keypad with your hand so no one can record your pin.
To avoid a skimming risk entirely, use cash.