Something I learnt today: why ATMs eject cards unevenly

skimming deviceHave you ever wondered why your card does not slide quickly and smoothly out of an ATM? It turns out this is a deliberate design feature from the manufacturers to make it harder to skim information from your card.

One of the essential elements of a card-skimming scheme is reading the information from the magnetic stripe on the card. Most skimmers do this as the card is coming out of the machine as that’s more predictable than when someone is inserting the card into the machine. So the ATM manufacturers deliberately build a jitter into the mechanism to make it harder for the card to be read. That’s what I learnt today.

This was a bit top-of-mind for me at the moment as my own bank introduced a shiny green new feature on their ATMs to help defeat skimmers. Unfortunately my first reaction was that it was itself a skimming device – and in fact it looks remarkably like the skimming device in this photo from earlier this year. It sort of amazes me that banks don’t post up a little photo of how their ATM is supposed to look beside the ATM itself.

Photo: George Slefo

One thought on “Something I learnt today: why ATMs eject cards unevenly

  • May 15, 2013 at 9:16 pm

    Hi Evan,

    Working on a very large ATM project at the moment.

    My advice to people, let that card jitter.

    Amazingly those devices aren’t as effective as you would think. Many people simply push their card into the machine then yank it out when they are done negating any good the jittering mechanism would do if there is a skimming device attached.

    So the moral of the story is – be a bit more patient. 😉


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