I'm sure you have loyalty cards for several stores in your wallet or purse. These give you rewards like cheaper purchases, airline miles, points toward online shopping and other bonuses.
Unfortunately, it turns out you're not the only one who can benefit from those bonuses. Many rewards sites aren't as secure as they should be, which leaves them open for hackers with a little time on their hands.
This was proven recently when crooks stole 250,000 rewards points - worth around $1,200 - from Brendan Brothers' Hilton Honors account. The thieves used the points to book rooms up the East Coast. Then when the points ran out, they tapped the corporate credit card linked to the account to buy more.
Brothers can probably get the credit card charges reversed, but getting the points back is up to Hilton.
Of course, thieves don't have to use the points themselves; they can sell them online to other criminals. It's an untraceable way for someone to travel or hide out in a city - it's all in your name. And you probably won't even notice until you want to use your points for something.