Tale as old as time: Woman tries to withdraw $5. ATM spits out $100. She goes back multiple times to exploit this flaw. Gets sued by the bank, who wants all of that money back PLUS interest.
Y'know. That old chestnut.
Is she MORALLY in the wrong? Sure.
But in my opinion, it's up to the bank to make sure their machinery is functioning properly.
Get all the dirty deets here.