Consider the history of any recent corporate scandal, and it is quite possible to guess what the story began with: a poorly secured file. No complex hacker intrusion, no state-sponsored attacks, just a document that had been sent to the wrong address, left in an unprotected storage space or forwarded to a person who could hardly be trusted with confidential information.
As for modern businesses, they almost certainly store some sort of confidential data and exchange it in a manner that is far f