Is the software for these ATM machines open source and in github somewhere?
ATM's often do use some embedded windows as operating system
Anything that runs on top is (most probably) not disclosed to the public.
I wouldn't be surprised if there were a ton of vulnerabilities which could be exploited with full access to the device.
I wouldn't trust these machines at all, they are probably keeping a log of all the movements and handling them to authorities to get your ass in trouble.
They definitely keep logs, such as timestamps, duration, withdrawal/deposit, camera, etc..