ATM security is often discussed as if it were a single feature. In practice it is a set of layers: the box, the device, the communication path, the network, the monitoring, the detection, and the people who operate it.
No single layer is enough
A strong enclosure with weak communications is a vault that talks in the open. Strong encryption with no physical sensors is a secure conversation about a machine being cut open. The layers exist because the threats are mixed.
What this site will not do
A public explanation of ATM security should stay at the level of architecture and intent. Implementation details that would help an attacker do not belong in a corporate article.
Security is not a feature we add. It is what we start from.