I find it pretty hard to believe that saving a sensitive information file in a hidden location was an accident. Programmers, lead by a specification which was designed by their team (or managers) developed the application to save the file in this manner.
Today’s computer viruses are largely financially driven. They target sensitive information such as identities, credit card or bank account numbers and other data that can be used or sold for profit. Many variants exist and they will attack using different strategies.