So Telstra had a good one...
You know how all Telstra passwords used to be Bigpond1?
Well I changed back to Telstra a few years ago, and had a third party ring me trying to get me to switch over to some service. Anyway I had way too much time on my hands so I talked to her for ages, and asked them where they were and the weather and stuff but whenever they asked for some Id stuff I'd say that I don't give that over the phone to people who have called me, they have to give me some proof they're from the company.
Anyway she knew my address and my last months spend. So they had been spamming bigpond account logins with bigpond1 to get access to all the account verification details... then if you fell for it they wound switch your number over, they had some basic billing information so xould find your bank account, and then the endgame is drain your account.
Tried telling Telstra and the customer support guy couldn't have cared less; but I think the default is slightly more random now so might have closed it.
Imagine that. It affected a lot of people; I don't think there are all that many that cracked the problem. Telstra could be up for a lot of money if a few people who lost got together