Unlocking Shopping Carts with Phone Speaker Sounds: A DEFCON 29 Hack
2025-08-22
A hacker, @stoppingcart, demonstrated at DEFCON 29 a method to unlock electronic shopping carts using a phone speaker. Most electronic shopping cart wheels listen for a 7.8 kHz signal from an underground wire to lock and unlock. The hacker created a 7.8 kHz audio file and used the parasitic EMF from a phone's speaker to 'transmit' a similar signal, unlocking the cart. This exploits a vulnerability in the cart's security system, highlighting a security flaw.