There has been a vast increase in the number of phishing e-mails in circulation over the past six months, according to online security services firm MessageLabs.
Swiss bank Basler Kantonalbank is the latest to warn its customers of the scam e-mails, which claim to be from legitimate banks but direct recipients to a replica Web site where they are asked to enter personal security data that is used to make fraudulent online transactions.
MessageLabs says it recorded 279 scam e-mails in September 2003 but by March 2004 this figure had risen to 215,643. The number of phishing e-mails peaked at 337,050 in January 2004.
In the UK, customers of Barclays, NatWest, Lloyds TSB and Halifax have been targeted, while in North America, customers of TD Canada Trust, Citibank, Ebay's PayPal and Visa have fallen for the scam. Customers of the four main banks in Australia - ANZ, Westpac, National and Commonwealth - have also been targeted.
Mark Sunner, chief technology officer, MessageLabs, claims the increase in the number of phishing e-mails is evidence that the number of individual scams has also risen dramatically.
"For targeted organisations the impact can be high - including lost productivity, customer confusion and complaints, damage to the brand and legal implications. For individual users, the financial losses can be excessive. If allowed to continue unchecked, online phishing scams threaten to undermine confidence in e-commerce as a whole," says Sunner.