Performing transactions at ATMs is quite familiar to many people, but there is certainly an interesting detail that almost everyone overlooks. That is, most bank ATMs use metal keypads instead of other materials.
With today’s technology, there are many alternative materials that could be used, such as plastic and rubber. They could even combine different materials to create a keypad with an attractive LED backlight, similar to the mechanical keyboards you use for gaming at home. Why do they always have to be cold, unfeeling, and unattractive buttons?
It turns out there is a common reason for this issue. Most bank ATMs use metal keypads because they have an important advantage: they prevent the leakage of customers’ confidential passwords.
According to research and monitoring by a group of security researchers at UC San Diego, the PIN you enter on the ATM keypad leaves a thermal trace.
By using a digital infrared camera, an attacker can identify which keys have been pressed.
If someone is watching you while you use the ATM, your PIN can be stolen immediately. Why? Because just by using a digital infrared camera, an attacker can accurately determine which keys have been pressed with up to 80% accuracy. Their research shows that even one minute after you enter your PIN, the infrared camera can still display the correct numbers for a short period.
While it is easy to identify the numbers in a PIN with an infrared camera, determining the order of those numbers is not as straightforward. Therefore, attackers seem to specifically target ATMs with plastic keypads – a material that can retain heat for infrared cameras, which certainly helps them distinguish which keys were pressed.
An attacker can observe the depth of the colors to infer the order of the numbers you pressed.
Looking at the image above, you can see that this plastic phone button can be detected after being photographed by a thermal sensor camera. The intensity of the color can determine the order of the buttons, with the lightest being button number 1 and the darkest being button number 5.
Attackers can observe the depth of the colors to infer the order of the numbers you pressed. Therefore, it is clear that if you use a keypad made of this material, you can easily become a victim of password theft.
Metal keypads have high electrical conductivity.
In contrast, when using a metal keypad with high electrical conductivity, the temperature changes relatively quickly, making it difficult to detect the order of the buttons through thermal touch. This way, your bank account is kept safe.
To prevent situations where ATMs only use plastic keypads, you should place your hand over the entire keypad to transfer heat to each key after you enter your PIN and complete your transactions.
Nevertheless, being cautious in all situations is essential to avoid unfortunate consequences.
