This video proves why it pays to be vigilant when money is involved. Security engineer Ben Tedesco was touring Vienna in Austria when he came across a suspicious-looking cashpoint, and decided to hit the record button when his instincts told him something wasn't quite right.

As it turns out, the cashpoint had been equipped with an ATM skimmer, a fraudulent card reader used by thieves to capture information from bank cards. The device had been placed over the machine's real card reader and had been designed to look exactly the same as the genuine article, making it hard to spot. They can be built from scratch – made easier in recent years, thanks to the rise of 3D printing – or purchased on the dark web.

The skimmer had been installed on an ATM in Vienna's main square, close to a metro station and a number of hotels which made this a prime spot for tourists. There's no way of knowing how many fell foul of the ploy before Tedesco arrived, however thanks to him it was removed before any more damage could be done.

Tedesco, who works for a security company called Carbon Black, plans to reverse-engineer the ATM skimmer to see how it was made.

ATM skimmers can come in various shapes and sizes, and are usually installed alongside hidden cameras used for capturing your PIN. The general advice for spotting them is to look out for anything that isn't flush with the machine – in this instance, Tedesco spotted the glue around the rim of the card reader where it had been attached to the ATM. Sometimes, skimming keypads are also installed to capture you PIN, so it's always worth giving dubious ATM parts a tug if you're ever in doubt. If you're still unsure, just move on – the risk isn't worth it.