nelson says she and her husband have finished the majority of their holiday shopping, object lynn. -- online. >> amazon, ebay, macy's, all of them. >> reporter: one in three major retailers has its own app, but criminals are cashing in, making counterfeit apes, app, with the same names. is. >> for every single retail brand you see the name on the map at the mall. >>> there is a fake app for that company, in fact, there could be dozens. >> reporter: cyber security expert says the hackers' goal is to get your personal data. >> when they type in their user name, password, and put it the credit card information, the counterfeit apps are steel that information. >> reporter: the app are so good, shoppers don't notice. >> they give you a complete shopping cart experience. everything through the congratulations, here's your order number. it's on its way. and you never get the goods. >> reporter: it's not just fake apps, but the cute faces, that can get access to your personal information on some phones, possibly your passwords. best way to avoid bulb tricked by -- being tricked by a fake app,