Swift, the interbank messaging system embroiled in one of thelargest cyber heists in history, warned customers that hackers havestruck again, attacking a commercial bank client that it didn'tname.

The details of a second hack follow a cyber theft in February,when more than $80 million was stolen from Bangladesh's account atthe Federal Reserve Bank of New York. Swift last month warned userslast month that it was aware of several similar attacks.

This time, the hackers used malware to target a PDF reader usedby the customer to check its statement messages, Swift said onFriday. A Swift spokesman declined to reveal the name of the bank,but a U.K.-based security firm, BAE Systems Plc, said in a blog post that it believes the second victim is acommercial bank in Vietnam. BAE isn't directly involved in theinvestigation, but analyzed malware samples uploaded to publicrepositories from locations in both Bangladesh and Vietnam andfound a match.