Mitnick had so many stories that entranced the people around him. I heard one second hand of Mitnick dealing with a bank who had early voice verification software. Upon meeting the CEO he gave the executive his card and departed for the evening. Arriving back at his hotel, he called the CEO and asked him to read his phone number to him. The phone number contained all ten digits which Mitnick had neatly tape recorded so as to make the CEO’s voice reproducible. He then proceeded to use the bank’s vocal banking system to transfer $1 from the CEO’s account to his as the authentication mechanism was reading out your own account number in your voice.
When Mitnick arrived back in the board room the architect of the voice verification system was crestfallen and the bank CEO delivered a check on a silver platter.
Now how much of that tale is embellished I will never know as it was second hand, but that was the kind of whimsy Mitnick brought to our world.
Rest in Power.
The phone number contains all the digits needed to recreate the bank account number?
He somehow has the bank account number?
He meets the CEO (despite just being a security consultant) and gives his report to the board of directors?! That is not how companies usually work, especially the board part.
Check on a silver platter? architect of the voice system is brought into the room with the board to be humiliated? This reads like something a 13 year old would dream up (nothing against OP maybe someone even Mitnik really did claim this happened).
The tale is absolutely embellished if it has any truth at all.
It's incredibly easy (still) to do certain kinds of "social engineering". Terms like "psychological sleight-of-hand" can sometimes make it a little clearer how humans just have blind spots - ways our perception works and doesn't. And, people who are used to being VERY "in control", intelligent / experienced (compared to others in room), etc., can sometimes be the easiest to manipulate in certain ways.
But, really, it boils down, sometimes, to something as simple as "how long can you keep a person talking?" Mitnick was probably in a good position to do these sorts of things - assuming the story is from after he "turned White Hat". And, in this case, the even simpler deal with the numbers is something like "oh, shoot, I had a misprint on old cards, did I give you the right one? What's the phone number on it?" Drop something abruptly like that, at some random point in a conversation, most people wouldn't think twice... Even if their current context involves a heavy dose of thinking about voices and numbers. They might easily enough realize in the morning, but, too late, by then. Further, getting bank account numbers is not necessarily hard either. Could even be as simple as "dumpster diving", back then. Did the CEO always shred every single document, with a "secure shredder" (as much as that's possible) when home? Or maybe burn everything, always?
And, in any case, you're even mixing up aspects of the story. The phone number isn't the bank account digits, it's just all the numbers from 0 through 9 (you can even get one twice, for a 10-digit [w/ area code] number).
I propose that your sureness in dismissing this story, misapprehensions about it, etc., make you an unwittingly "good mark."