In-Depth

Top Twenty Virus List for October 2003

A newcomer dominates this month's list

• By Kaspersky Labs
• 11/05/2003

First, the Klez and Lentin Internet worms, mainstays on the Virus Top Twenty list (since November 2001 and March 2002 respectively), dropped off the list. Additionally, the Sobig Internet worm that has occupied the top spot over the past several months fell to the eighth position.

Currently, a newcomer—the worm Swen, appearing in mid September—occupies the top spot. In fact, Swen dominates the list by claiming over 70 percent of all registered incidences, while its closest rivals, the Tanatos and Mimail worms, accounted for just over 1 percent each.

Another unexpected occurrence in October is the significant growth in the number and variety of Trojan programs appearing. An impressive total of nine malicious programs belonging to the Trojan family made the list. In aggregate, Trojan programs well over doubled the total turned in by computer viruses—6.46 percent to 2.77 percent.

Here is list of the top twenty most widely spread viruses for the month of October.

Name and Percentage by Occurrence

• I-Worm.Swen 70.94%
  
• I-Worm.Tanatos 1.13%
  
• I-Worm.Mimail 1.07%
  
• Worm.Win32.Lovesan 0.89%
  
• Backdoor.SdBot 0.70%
  
• I-Worm.Sober 0.63%
  
• Worm.P2P.SpyBot 0.59%
  
• I-Worm.Sobig 0.52%
  
• Backdoor.Ciadoor 0.47%
  
• VBS.Redlof 0.39%

• TrojanDropper.Win32.Small 0.38%
  
• Backdoor.Agobot 0.30%
  
• Win95.CIH 0.29%
  
• Backdoor.Optix.Pro 0.28%
  
• TrojanProxy.Win32.Hino 0.23%
  
• Backdoor.IRCBot 0.23%
  
• Win32.Parite 0.22%
  
• Keylogger.Win32.PerfectKeyLogger 0.21%
  
• Macro.Word97.Flop 0.18%
  
• Trojan.Win32.StartPage 0.18%

Other malicious programs 20.17%