Happy friday. Oh, the duality of man. One person's brilliance creates technology, while anothers exploits that same idea in order to rip us off. Case in point, the self-serve gas pump. Earlier this... See More
Happy friday. Oh, the duality of man. One person's brilliance creates technology, while anothers exploits that same idea in order to rip us off. Case in point, the self-serve gas pump. Earlier this summer we caught on to a scam so clever, countless, unwitting folk were driving away with a full tank and much lighter wallet. But we found a man well versed in the skim scam who start tupd listen to his better angels and gave abc's nick watt the tips you need to protect yourself for this "nightline" on the lookout. Reporter: You are watching what police say is a new breed of credit card thief, caught on tape. They say that guy is searching for a so-called skimmer device. Installed this gas pump in arizona. Stealing your credit card info when you think you are just paying for gas. What he doesn't know, according to investigators, is that he is just been caught in a covert sting operation. He put those in there for whatever reason, they're not there anymore. I know why. Because I have them. He is the one who tipped us off. He is the one who switched out that skimming device for a night vision spy camera. We may have the first ever video of organized bad guys actually trying to retrieve their skimmers. That's video gold. Here comes our producer pulling up to buy gas. He swipes his credit card, and for all he knows, for all the gas station owner knows, crooks could be stealing from him right then and there. The skimmer inside the pump, silently harvesting his credit card information. He has no way of knowing. And this its how a multibillion dollar a year problem. That's where I found mine. It was stuck up here. Unless you are looking like this, you can't see it. Look at the little match box, that's it. Stuck on one side to the middle. He recently found a skimming device inside one of his pumps. He has been in the gas business a long time. And played us the greatest hits from the surveillance video collection. They used to come in with a gun. Or used to break the windows at night. That its so last century. The skimmer wouldn't stick a gun in your face. There its nothing hiding his eyes. They will, well they'll rob you blind. The skimming device found inside ahmad's pump sat there for months. He had no idea. Skimming all across this country, got so bad that steve scarince, and the united states secret service yep, the same guys who protect the president they are now on the case. Are you winning the war? It's even, right now. We are doing our best. We certainly could use more help. Getting help from police departments, tipoffs from gas station owners and just wait until you meet one of their secret weapons. Somebody turned my partner in, he turned me in. Dan felipe is a reformed credit card hacker. He switched side. He was caught by the secret service. And then spent two years training agents in the dark art of skimming. It is very easy. It's -- a lot of money. You can make tons of money. Gas station skimming is one of the easiest and best ways of doing it because it is hidden. It only takes second to open it up and put it in there. So this is the reader that will be inside the gas pump. And so you would just swipe it through and it wouldead it right here. So you just add this into the circuit? That's exactly it. What you would do is unplug this. You would take the skimmer and plug it right back in. Knob would k nobody would know the difference. How do they get into the pumps? Believe it or not there is a universal key that opens most gas pump doors. A universal key. Universal key. The same key from mals massachusetts to california. You can buy one on line. Some of the newer devices use the data to transmit. Reporter: A bad guy can nab your numbers without risking a return to the pump. Then his option number one is to just sell your credit card number, sort of e-bay for skimmers. How much is my number worth? Anywhere from $5 to $30. Jeez, not much. Are you nervous yet? Watch this. I would have an exact copy of your card. One swipe. One swipe. That's it. That its option number two. Clone a card. And that's how easy it is to transfer your stolen credit card details on to a fake card. I was printing my own fake credit card. I would go to the store. Purchase, electronics. I would resell them. So how do we stop guys from going on shopping sprees with your credit card info. Well, the arizona department of weights and measures is trying to stop this high-tech heist at its source. Wre are here checking for skimming devices. It was when they found a skimmer in the pump that they had their bright idea to lay a trap. They pulled out the skimmer and -- we inserted one of the little night vision spy-cams in the back of the dispenser. Here is the full video from their operation. 2:00 a.M., A black suv pulls into the gas station. Picked up on the surveillance camera. Police tell us one guy blocks the attendant's view. Two people punch over the pump. Bingo. Here is the view from that camera inside. A skimmer-cam, police say, apparently a man and woman team caught red-handed. What we have here, we have the guy. And I have this. It's awesome. They can't find their skimmer, they start dickering. Almost like a husband and wife team, arguing where is the car keys. The cops are searching for mr. And mrs. Skimmer. For the man and his crime spree ended when he was spotted shop b b -- shopping at a best buy with a fake credit card. Anything I want I'd would go out and get for free with the card. Reporter: Then shopping sprees with counterfeit card left a trail too easy to track. It's old-fashioned. These days, skimmers have a new way of turning stolen credit card into cash. Lookike a normal truck on the road. You open it. Not such an ordinary struck. 300-gallon container. Home made. Steel. Doesn't look safe. After installing huge hidden tanks, skimmer gangs go become to the gas station and fill them up at the pump. Paying for the gas with your stolen credit cards. Look at where this guy has inserted the pump nozzle. Up so high it can access that secret compartment. I would never suspect someone would go to that much trouble. Off awe absolutely. They transfer tight a regular tanker. And make what looks like a legitimate delivery to a gas station owner. Voila, gas for cash. 8 million to $10 million a year. Cops in l.A. County say they're pulling over trucks like this at a rate of one a week. What on earth can you do to protect yourself and credit card digits. There is no point looking at the pump for clues. You would never know. No way of knowing. While gas station owners are looking for locks and alarms, here are some other thing that the you can do. Check your account. Most credit card companies will suck up any loss if you report it. Within 60 days. Choose wisely. Choose a pump near the attendant. Skimmers prefer to target pumps in the shadows. And -- don't forget, you don't actually need to put your card anywhere near that pump. You can always pay inside. Word of wisdom there. Thanks to nick watt for that.
This transcript has been automatically generated and may not be 100% accurate.