Malicious software such as Trojan worms is the new trend in online threats in the first half of 2006, as the virus number diminishes. A study released by the online security company Sophos PLC indicates that, compared to the last year, e-mails infected with viruses are considerably less frequent. In this regard, if in 2005 one out of 35 e-mails was infected, nowadays this percentage has dropped to only one in 91 e-mails.

"E-mail, as far as viruses are concerned, is actually safer than it was last year," said Graham Cluley, senior technology consultant at Sophos. But things are not as simple as they appear. Statistics show that the number of online threats has no less than tripled last year and that it continues to grow, spyware and Trojan worms being on the rise.

This is equivalent with non-stochastic attacks and premeditated threats. Sophos has reveled that 81% out of the Internet malware traffic analyzed was comprised of Trojan worms. Keyloggers, malware that harvest data from an infected computer, from passwords to credit card numbers used in online transactions, and sends them to a remote server controlled by the hacker, represent a large part of this percentage.

No. 1 in Sophos malware ranking is Sober-Z, a worm that has infected 22.4% of all viral e-mail although it has been active only for six days in 2006. Coming in second and third are two mass-mail worms that have been active for a couple of years: Netsky-P and Zafi-B.