Top Ten viruses detected by Panda ActiveScan in October

Bugbear’s explosive entry on the scene has knocked Klez.I off the top of the virus ranking for the first time in six months

Panda Software, leading antivirus software developer, has released October’s Top Ten list of viruses most frequently detected by Panda ActiveScan, the company’s free, online virus scanner.

During this period, a number of new and dangerous viruses have emerged, and one of these, Bugbear, has rapidly replaced Klez.I as the most active malicious code in existence.

The reason behind the dominance of Bugbear, recorded as the culprit in more than 20 percent of infections, is in part, due to the use of ‘social engineering’ techniques and also the difficulty users have in identifying it, as the e-mail and attachment carrying it have numerous guises. This worm also exploits a vulnerability in Microsoft Internet Explorer to run automatically simply when the e-mail is viewed in the Preview Pane.

Second in the list, not far behind Bugbear, comes Klez.I, one of the most persistent malicious codes to date and one which like Bugbear, exploits a vulnerability in Microsoft Internet Explorer to run automatically.

Other viruses detected in October include Trj/PSW.Bugbear, a Trojan that records user keystrokes. Trj/PSW. Bugbear hides in .dll. files created by Bugbear in infected computers.

The rest of the viruses that make up the Top-Ten were all recorded in less than five percent of cases. In fourth place comes Elkern.C, a malicious code installed on infected computers by Klez.I, while fifth and sixth place are occupied by two of the many variants of Opaserv, which through their unusual means of propagation across the Internet, have become some of the year’s most notorious viruses.

Finally, at the tail end of this month’s list come the old enemies Nimda, Magistr.B, Sircam and Klez.C.

Virus % frequency
W32/Bugbear 20.10%
W32/Klez.I 15.67%
Trj/PSW.Bugbear 9.51%
W32/Elkern.C 4.77%
W32/Opaserv 3.81%
W32/Opaserv.E 3.62%
W32/Nimda 3.13%
W32/Magistr.B 3.03%
W32/Sircam 2.75%
W32/Klez.C 2.54%

To help users keep viruses from spreading, Panda Software offers Panda ActiveScan, to Internet users free of charge, at ( ActiveScan is also available to webmasters that want to include it on their websites. Administrators can request the HTML code from, indicating the web page on which they want to include it.

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