Fraudsters are using bank mergers as an opportunity to craft customized phishing scams timed to transitions between the banks' online systems, hoping that customer awareness of mergers will bring more bites on "bait" emails.

Wachovia Bank issued a warning about phishing emails "designed to capitalize on our merger activities. We will not send any conversion communications by email during the merger," said Wachovia, which is currently integrating the operations of SouthTrust. The bank said all information about the online migration of SouthTrust customers will either be sent by U.S. mail or through internal messages to customers using the online banking system.

The wide adoption of online banking means that most industry mergers will include a consolidation of IT systems and customer accounts, offering phishing crews a steady supply of migration scenarios to target. There were about 1,500 bank mergers per year in the U.S. between 1996 and 2002, according to the Federal Reserve.

Wachovia, the fourth-largest U.S. bank with more than $500 billion in assets, acquired SouthTrust last November. SouthTrust has been a persistent target of phishing scams, having been targeted in more than 100 separate attacks this year.

While headlines have focused on megamergers between industry giants, much of the acquisition activity involves growing regional and local banks. These smaller banks and credit unions have been increasingly targeted by phishing attacks in the last several months, as phishers adapt their strategies to seek easier prey. While consumer education about phishing has been a priority for the entire U.S. banking industry, small banks have been less active in this regard than the huge banks that were the primary targets in early phishing scams.

The flip side of the equation is that most U.S. banking customers have experienced at least one merger in which their accounts have been migrated (and often three or four) and are thus familiar with receiving transition information by mail.

Customized versions of the Netcraft toolbar can provide banks and credit card companies a powerful tool to protect their customers and networks from Internet phishing scams, a capability which could prove especially useful during customer migrations.