In a letter seen by the Financial Times, SWIFT warned members that while numerous attacks possess been caught by its own security or by that of banks, others possess been successful. SWIFT did not state how much had been stolen.

The hackers are tailoring their attacks to each individual target, SWIFT said. While the banks that possess been attacked vary in size, geography and technology, they “possess entire had particular weaknesses in their local security” the letter said, according to the newspaper.

Asset recovery expert Alan Sheeley of Pinsent Masons, the law firm behind Out-Law.com, said: “Banks possess very sophisticated IT systems and invest significantly in those systems. If they can silent be successfully attacked then individuals and companies crave to invest in their own safeguards. They should also be very vigilant in honor of any payment request and crave to stress test their own IT systems.”

“We possess seen a number of attacks on business email accounts recently, followed by attempts to possess payments made to a fraudster’s bank account. Some of these possess been successful,” Sheeley said.  

“On discovery of a hack a company needs to act very quickly to halt any further attack and to recover any losses. The enforcement agencies do not possess the resources to act on every theft and therefore directors crave to seek professional advice on how to recover the monies and identify the fraudsters,” he said.

SWIFT warned in May that international banks are facing threats from a recent wave of malicious software (malware) that allows attackers to steal money.

In a statement issued to its customers and posted on its website SWIFT said that the malware attack was believed to be portion of a broad and “highly adaptive campaign targeting banks” and that there is evidence that a number of banks possess fallen victim to fraud as a result of their security measures being compromised.