"When these cards are in a common area of the store, what these scammers do very well is they take the cards and tamper with that code on the back ... and return those cards to the shelf," Matthews explained.

"So once somebody comes in and buys those gift cards, they are activated at the point of sale. The scammer has [the information], and they can drain the card of everything that the purchaser thought was going to be on the card as a gift."