Phishing scams have overtaken the number of emails containing viruses and Trojan horse programs for the first time, new research shows.

The latest MessageLabs report found that one in 93 (1.07 per cent) emails sent last month comprised some form of phishing attack. The number of messages containing viruses or Trojan horses was lower at one in 120 (0.83 per cent).

This change is partly due to virus attacks becoming more targeted and no longer occurring as one large outbreak, including the recent StormWorm and Warezov, according to the report.

Security experts also attribute the shift to phishing attacks becoming more sophisticated as hackers try to circumvent two-factor authentication, employed by growing numbers of online stores and banks, which has given rise to “man-in-the-middle” phishing sites.

Increasing numbers of phishing websites are now using Flash content rather than HTML in an attempt to thwart anti-phishing technology installed in web browsers, the research added.

“We are seeing malicious virus and phishing attacks increase in sophistication and ability to evade many preventative technologies,” said Mark Sunner, chief security analyst at MessageLabs. “Certainly consumers are the most vulnerable to phishing attacks and Trojans, but these problems also represent rising costs for many businesses.”