ATM Machines tutorial tips & tricks

JACKPOTTING was done rather successfully a while back in (you guessed it)
New York. What the culprits did was:
Sever (actually cross over) the line between the ATM and the
host. insert a microcomputer between the ATM and the host. insert
a fradulent card into the ATM. (card=cash card, not hardware)
What the ATM did was: send a signal to the host, saying "Hey! Can I
give this guy money, or is he broke, or is his card invalid?"
What the microcomputer did was: intercept the signal from the host,
discard it, send "there's no one using the ATM" signal.
What the host did was: get the "no one using" signal, send back "okay,
then for God's sake don't spit out any money!" signal to ATM.
What the microcomputer did was:
intercept signal (again), throw it away (again), send "Wow! That
guy is like TOO rich! Give him as much money as he wants. In
fact, he's so loaded, give him ALL the cash we have! He is
really a valued customer." signal.
What the ATM did:
what else? Obediently dispense cash till the cows came home (or
very nearly so).
What the crooks got:
well in excess of $120,000 (for one weekend's work), and several
years when they were caught.
This story was used at a CRYPTOGRAPHY conference I attended a while
ago to demonstrate the need for better information security. The
lines between ATM's & their hosts are usually 'weak' in the sense that
the information transmitted on them is generally not encrypted in any
way. One of the ways that JACKPOTTING can be defeated is to encrypt
the information passing between the ATM and the host. As long as the
key cannot be determined from the ciphertext, the transmission (and
hence the transaction) is secure.
A more believable, technically accurate story might concern a person
who uses a computer between the ATM and the host to determine the key
before actually fooling the host. As everyone knows, people find
cryptanalysis a very exciting and engrossing subject...don't they?