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How Bank Hacking Works

A certain number of financial institutions that reside within the
packet-switched confines of the various X.25 networks use their connections to
transfer funds from one account to another, one mutual fund to another, one
stock to another, one bank to another, etc... It is conceivable that if one
could intercept these transactions and divert them into another account, they
would be transferred (and could be withdrawn) before the computer error was
noticed. Thus, with greed in our hearts, an associate and I set forth to test
this theory and conquer the international banking world.

We chose CitiCorp as our victim. This multinational had two address
prefixes of its own on Telenet (223 & 224). Starting with those two prefixes,
my associate and I began to sequentially try every possible address. We
continued through 1000 in increments of one, then A-Z, then 1000-10000 by 10's,
and finally 10000-99999 by 100's. Needless to say, many addresses were
probably skipped over in our haste to find valid ones, but many we passed over
were most likely duplicate terminals that we had already encountered.

For the next few days my associate and I went over the addresses we had
found, comparing and exchanging information, and going back to the addresses
that had shown 'NOT OPERATING,' 'REMOTE PROCEDURE ERROR,' and 'REJECTING.' We
had discovered many of the same types of systems, mostly VAX/VMS's and Primes.
We managed to get into eight of the VAXen and then went forth on the CitiCorp
DECNET, discovering many more. We entered several GS1 gateways and Decservers
and found that there were also links leading to systems belonging to other
financial institutions such as Dai-Ichi Kangyo Bank New York and Chase
Manhattan. We also found hundreds of addresses to TWX machines and many
in-house bank terminals (most of which were 'BUSY' during banking hours, and
'NOT OPERATING' during off hours). In fact, the only way we knew that these
were bank...