Kaspersky Lab has published its list of the most prevalent viruses for the end of 2007, and although an email worm retains the top spot the more interesting stuff is happening immediately below it in the rankings of shame.
Specifically, the second, fourth and seventh places which are all occupied by variants of the Trojan-Downloader.Win32.Diehard. The .dc modification of this Trojan dropper only appeared for the very first time on 21st December, yet on some days in December it proved virulent enough to account for some 80% of all the malicious traffic seen in email by Kaspersky users. Droppers are particularly worrying, because these deploy the Trojan components that are required to control computers in order to send spam. Think the Warezov family of worms that were so successful during the course of 2007 and you are not far off the mark. In fact you are bang on it, as the Diehard Trojan does pretty much exactly the same thing.
Of the entire top ten viruses on the list, eight are new entrants. The first time this many newcomers have dominated the list for the longest time. A Kaspersky spokesperson said "these trends threaten to provoke significant changes in mail traffic in the near future. Contrary to predictions, Trojan programs and phishing attacks are ending up near the top of the table more and more frequently. Classic email worms re-enter the rankings, then disappear again, creating a backdrop for the real battle which is taking place. And although these events are not on the same scale or as long lived as epidemics of previous years, they are no less dangerous."