You can certainly let the banks that received the wires know that your customers system was breached and that they will be filing charges and looking to come after the recipients; I have done this in the past and it sometimes worked, sometimes didn't. Contact each bank that received wires directly and ask to speak to their security officer. Let them know what happened, and most will work with you. Ultimately, as Randy said, iot is down to you and your customer, strength of contract, and what multi-factor device they were using and how old their PC security software is...
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