There really isn't a direct answer to the question in your headline. There are several mechanisms and networks via which you can make an "international wire transfer" and, essentially speaking, there isn't one single all-powerful org balancing everyone's books all at once for all possible transfer mechanisms. But that's OK, because the systems are built to not need one, and the fundamental way that money works makes it unnecessary anyways.
Your proposed scenario hinges on two specific activities that would either be hard to implement or would be easy to discover after the fact, to the point that you'd be easily stopped trying to carry this plan out, or caught after the fact, probably quicker than you could spend your fake money.
- Suppose bank A creates a new account, and adds 1000 euro's to it, by just changing the relevant field in the database from 0 to 1000: Most banking systems have internal mechanisms to prevent this from happening - i.e. you can't simply change a value in the database without repercussions. Sometimes these mechanisms are fairly passive (an exception report would be generated showing that the books don't balance) but other times they are more robust (balance and transactional amount data is encrypted and not directly editable in the database, you'd need to defeat an app-level mechanism in order to change it. Or, tables storing this info have triggers implemented that balance transactions and accounts automatically). Banking systems are also built with databases that include lots of auditing, so generally speaking, even if you managed to change the database value, you'd be leaving a permanent record (often in a different system with separate access controls) of what you did. Even if people didn't notice this activity immediately, it would certainly turn up during an audit.
- Your proposal for hiding the fake money (presumably, as a way of explaining where the 1000 euro came from) was It then makes up an incoming transaction to cover the 1000 - by this, I'm assuming you're indicating that the fraudster would edit an incoming file for wire transfers to create a new transfer for the fake money. The problem with this, is that wire transfers aren't single-ended transactions - there's essentially always a "from" and "to" entity and account. Networks implement feedback mechanisms to ensure that transactions process successfully - essentially, once banks process incoming transfer files, they produce a summary back to the network that explains the net changes in balance between themselves and other institutions. Then the network shuffles these amounts among the bank's funding accounts. If your bank got 1,000 transactions which resulted in a net of $1M in transactions from bank A and $2M from bank B, you'd report that back to the network. Your reports would match bank A's and bank B's and the network would move the money. Getting back to your plan - if you try to stick your fraudulent transaction into an incoming file, you'd need to include it in the feedback too, in order to not tip off the automatic checks in the system or the auditors (who will balance your incoming files against your return summaries), which would instantly be spotted by the network.
Basically, what it boils down to is, banks do not fundamentally create money. They simply hold it, or move it. By definition, this means that there isn't a way for your fraud scheme to work, because any transaction a bank can perform includes another party (who isn't "in" on your scheme) and some mechanism for validating the transaction. This applies to all mechanisms via which money can be moved, not just electronic transfers:
- Paper checks are processed through networks with similar feedback mechanisms to electronic transfers. If a bank employee tried to make fake checks from some random other bank to deposit, the other bank would know about it (and stop it) when they received the checks to complete the transaction. If an employee tried to make fake checks from a fake bank, the clearinghouse bank would find it and stop it.
- As cash turns over in a bank, it (eventually) changes hands to third parties. It's either issued to customers making withdrawals, or it's sold to another bank or a cash management vendor. A bank employee who tried to fund a fake account by either making counterfeit cash or just faking a cash deposit (without actually depositing anything at all), and who was smart enough to defeat automatic cash machines and cash drawer accounting within the bank's systems, would still get discovered when the bank sold that cash or tried to issue it to fund withdrawals.
So to make this all crystal clear, when you said,
and adds 1000 euro's to it
that's simply not possible, without including a third party, who - not being "in" on the fraud, would discover the scheme and turn you in.
