Look at everything
If you're willing to pay for it, Microsoft provides patches and fixes for Windows XP Pro until 2020.
It isn't cheap, but in cases where you don't have much choice... you know how it is.
ATMs are more/less PoS devices. Many applications haven't been updated to run on more modern OSs. If they have, the ATM owners (not necessarily the banks who lease them), won't spend the money on upgrading OS and applications until they are made to do so. Why should they? You'd save the money and pocket it yourself, right?
The number of increasing integrity attacks are starting to change minds, not to mention the cost of insuring old software/OSs. As is how much courts are starting to make examples of corporations who aren't being attentive to proper due diligence, and especially those who aren't attentive to proper due care. In-which using and old OS will likely hit the hardest in courts.
If you look hard enough, you can still find Windows XP in the US and western Europe. Mostly with companies who lease out older ATMs. For banks who own their own ATMs, these are likely updated with newer operating systems, and a wealth of physical security add-ons.