These are public facing bank services - so at some point have to be connected to the internet, quite a few banks use AWS for this [1]. I don’t know about Treezo

These are public facing bank services - so at some point have to be connected to the internet, quite a few banks use AWS for this [1]. I don’t know about Treezor but most of them will still have their own data centres for some or all of their ‘secure’ systems (if only because it’s running on some legacy hardware) [1] https://aws.amazon.com/financial-services/banking/ https://aws.amazon.com/financial-services/banking/