Well, the point isn't that my bank wouldn't "leak" my details - I certainly don't trust them that far. So it's absolutely possible for a random person to get my phone number from the bank. But if a random person were to phone me and tell me that my bank gave them my phone number to be helpful, I'd be calling that out as a lie.
If someone spoofs the banks number on caller ID (trivial), knows all your security question answers, the bank you bank with, and your number - very few people are NOT going to fall for some kind of attack there correct?
How could they figure out the internal account number without hacking into the bank in the first place? I’m fairly certain there’s no way to derive the account number from a debit card number or any of the info you mentioned.
Additionally, bank account ‘internal’ account numbers are pasted on every check that goes out and any ACH transfers also include that information, so it’s not like they are hard to cross reference with any of the other major breaches.
SSN, dob, which banks people use (and other financial institutions), which loans they have with whom, etc. also got leaked for pretty much every US adult with the equifax hack.
