Police authorities around the country are warning of a plague of ATM card-skimming.
Skimmers are devices attached to ATMs that can capture and store the data from a customer's card. Thieves generally also install a recording device of some kind - sometimes, an iPod - to peek at the customer's PIN number.
Most recently, a device was found attached to a Barclays cash machine in Station Road, Urmston. Greater Manchester Police tweeted: "Skimming device found on ATM at Barclays Bank #Urmston tonight. If you have used that machine this evening please contact your bank."
In Cambridge, meanwhile, a similar card-skimmer has been discovered attached to an HSBC cashpoint in Chesterton Road.
"It sounded as though the machine was trying to spit the card out and then the machine said 'Your card has been held – please contact your bank," victim Sarah Upjohn told the Cambridge News.
When she did, she was told that she'd been scammed.
"There was nothing for the untrained eye to look for on the cash point to tell you it had been interfered with," she says.
"When I walked back to the machine to have a look it was so obviously gouged there was glue running down the side of it. They had stuck a camera looking at the keypad and must have waited for me to leave because as soon as I had gone they took it out."
So how can you spot one?
First, be particularly careful at weekends. Thieves tend to attach the devices on a Friday night, removing them on Sunday to retrieve the data - it makes it harder for people to report suspicious ATMs to their bank.
Make it a habit to check for any obvious signs of tampering. Thieves often use a fake PIN pad on top of the real one, for example, so check whether it feels any thicker than usual.
Similarly, get into the habit of hiding your PIN number - not just from anyone that might be behind you, but also from any camera that might be attached to the machine. It should be possible to use one hand to screen what the other is typing.
Experts also suggest wiggling your card a little as you insert it. This is because data readers need it to go in in one smooth movement. The bank's genuine reader is on the inside, so won't be affected by a wiggle; but a card-skimmer attached to the front won't work.
And if you do fall victim, don't panic: as long as you report the incident to your bank or credit card issuer as soon as possible, you won't be held liable and your money will be returned.
Read more on AOL Money:
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