Like, they record how the ATM communicates the authentication portion of the transaction, and replay that same communication with the ATM until its stored cash has all been dispensed and it's now empty?
Had this fantasy in the 1980s when I noticed the student union ATM had what looked like an exposed Cat-3 phone cable sticking out of it. I naively thought "what if it's a modem, and you tapped the line, reverse engineered a withdrawal transaction, and then replayed the withdrawal ACK endlessly until you sucked all the money out."
As it happened, 20-odd years later, I ended up at dinner with the guy that ran that ATM network at the time. One, he said that was most likely a leased line, not a dialup, making the interception of the more complicated than an analog modem. Two, he said there was anti-replay and encryption built into the system even then.
His advice was to just steal the entire ATM.