Some idiot put some other idiot, kid, or incompetent bullshitter in charge of designing the network for a Financial company and they did what idiots, inexperienced kids and incompetent bullshiters do and put the Production machines in the same network and easily accessible by machines were users can install any random shit from the Internet.

Sooner or later something like what happened now would've happened.

The fault is entirely with the decision maker who chose to have somebody else other than a senior expert design the systems architecture of a business that is supposed to safekeep billions of dollars.