Kaspersky warns of major Trojan hike

The number of compromised computers at large on the internet has increased considerably over the past year with Trojan activity more than doubling, according to Kaspersky Labs.

The Russian antivirus company revealed a 124 per cent increase in Trojans intercepted between the first and the last month of 2005. Backdoor Trojans were the most common, accounting for 29 per cent of Trojan infections.

These forms of malicious code are typically used to create networks of compromised machines – or botnets. It is almost impossible to know the scale of the problem or get a handle on how many compromised machines are currently lying idle ahead of possible malicious use in the future, while their owners are oblivious to the threat.

According to MessageLabs, botnets now account for around 80 per cent of the world's spam.

Kaspersky also noted a dramatic rise in the amount of spyware in the wild, saying increases in both figures are further evidence of the financial motivation driving the production of malicious code.

Yury Mashevsky, virus analyst at Kaspersky, wrote in his report Malware Evolution 2005: "There was a sharp increase in the number of nearly all types of Trojan programs. The computer underground is becoming increasingly criminalised, focusing on accessing and using confidential information to gain access to profitable data, whether that be system resources, bank accounts, proprietary information or online games.

"Trojan programs can be used to gain access to such data."