Trojan attacks double in June

Trojans are mainly spread by spam but are increasingly being embedded in web pages

Security firms are reporting a worrying surge in the amount of new Trojan software circulating on the internet.

For the past few years mass mailing worms have been fashionable among virus writers, particularly those looking to create widespread outbreaks.

But the growth in Trojan detection demonstrates the increasing use of malware to steal personal information.

"It looks like Trojans are a real growth area," said Graham Cluley, senior technology consultant at Sophos.

"They don't tend to show up in virus charts because they don't self-replicate. It's a sign of the times; in the old days virus writers just wanted to make a splash, but now a new group is going after profit."

The trend is confirmed by a report into the prevalence of malware in June from firewall vendor Fortinet, which suggested that the incidence of new Trojans was up 100 per cent on the previous month.

"Trojans and backdoors accounted for five per cent of global virus activity in June," said Guillaume Lovet, team leader at Fortinet's European Threat Response Team.

"Although this seems very little compared to mass-mailer worms, which accounted for 68 per cent of total global activity, it marks a more than 100 per cent increase on May's Trojan activity, due to a new trend in virus propagation strategies."

Trojans are predominantly spread by spam but are increasingly being embedded in web pages and downloaded by poorly patched browsers.

The infected PC is then typically used as part of a network of slave PCs or to harvest financial information for identity theft.