Capt,
It's quite possible to hack the internet-facing web server and monitor the transactions that take place there, without ever getting inside their corp network to the central ledger/accounting system. The web server is outside a firewall, the corp network is inside.
For you folks with a cable modem or DSL connection, a $60 Linksys router will act a as simple firewall. It's plug and play with pre-configured basic protection. Without a router, your PC is facing the internet with a public (touchable-seeable-hackable) address. With a router, your PC's address is private, and the router has the public address.
