Virus Top Twenty for February 2007

02 Mar 2007
Virus News

PositionChange in positionNameProactive Detection FlagÄîëÿ, ïðîöåíòû
1.Up +3Email-Worm.Win32.NetSky.tTrojan.generic15.82
2.Down -1Email-Worm.Win32.Bagle.gtTrojan.generic11.85
3.New! NewEmail-Worm.Win32.Zhelatin.damDamaged*8.19
4.Down -2Email-Worm.Win32.NetSky.qTrojan.generic7.92
5.New! NewEmail-Worm.Win32.Zhelatin.oHidden Install +
Registry access
6.New! NewEmail-Worm.Win32.Warezov.lsHidden Install (x2)5.03
7.Up +2Net-Worm.Win32.Mytob.cTrojan.generic3.72
8.New! NewEmail-Worm.Win32.Zhelatin.uTrojan.generic +
9.New! NewEmail-Worm.Win32.Zhelatin.mHidden Install +
Registry access
10.Down -7Email-Worm.Win32.NetSky.aaTrojan.generic3.27
11.New! NewEmail-Worm.Win32.Zhelatin.rTrojan.generic2.87
12.New! NewTrojan-Downloader.Win32.Tibs.jrTrojan.generic2.43
13.New! NewEmail-Worm.Win32.Zhelatin.tHidden Install +
Registry access
14.Return ReturnEmail-Worm.Win32.Scano.genTrojan.generic1.83
15.Return ReturnEmail-Worm.Win32.Nyxem.eTrojan.generic1.66
16.Return ReturnEmail-Worm.Win32.NetSky.bTrojan.generic1.59
17.New! NewPacked.Win32.PePatch.grDamaged1.52
18.Return ReturnNet-Worm.Win32.Mytob.tWorm.P2P.generic1.39
19.Down -14Email-Worm.Win32.Bagle.genTrojan.generic +
Registry access
20.No ChangeExploit.Win32.IMG-WMF.yData Execution +
Registry access
Other malicious programs12.86
* — Non functional sample

In last month’s Top Twenty, we noted that Warezov worms had been almost totally beaten back by Bagle. Only a single Warezov variant remained in January's Top Twenty, and led the rankings. However, the world of computer viruses takes after nature, in that it abhors a vacuum, and as usually, new and more dangerous malicious programs have come to fill the void. This was the case in February, when we witnessed several epidemics caused by a new family of worms: Zhelatin.

Zhelatin is the ‘storm worm’ that got such wide coverage in the mass media at the beginning of the year. The worm spreads as emails with a range of topics designed to pique the recipient's curiosity - the terrible hurricane in Western Europe, the death of President Putin, and the resurrection of Saddam Hussein. Although Zhelatin was initially thought to be a new Warezov variant, closer analysis revealed a new family of malicious programs which probably originated in Asia.

During February we issued three virus alerts with a 'medium' threat rating. All these alerts were due to the rapid spread of new Zhelatin variants in mail traffic. Naturally, these outbreaks have had an effect on the February Top Twenty: out of the nine new malicious programs, six of them are Zhelatin variants. The struggle between Zhelatin and resulted in a veteran worm, Netsky.t, taking first place, while dropped back to second position. Zhelatin, meanwhile, managed by weight of numbers to occupy four of the top ten places.

When a new leader heads the rankings, there's usually a general shake-up, with new programs making their first appearance, and old viruses making a comeback. As noted above, there are nine new malicious programs in the February Top Twenty, and four re-entries, including some old friends such as Nyxem.e, Scano.gen and Netsky.b. This demonstrates once again that today's email worms have a long lifespan, and may be found in traffic years after their first appearance.

Other malicious programs made up a significant percentage (12.86%) of all malicious code found in mail traffic, indicating that a considerable number of other worms and Trojans are currently actively circulating.


  • New: Email-Worm.Win32.Zhelatin.dam, Email-Worm.Win32.Zhelatin.o,, Email-Worm.Win32.Zhelatin.u, Email-Worm.Win32.Zhelatin.m, Email-Worm.Win32.Zhelatin.r, Trojan-Downloader.Win32.Tibs.jr, Email-Worm.Win32.Zhelatin.t,
  • Moved up: Email-Worm.Win32.NetSky.t, Net-Worm.Win32.Mytob.c
  • Moved down:, Email-Worm.Win32.NetSky.q, Email-Worm.Win32.NetSky.aa, Email-Worm.Win32.Bagle.gen
  • Re-entry: Email-Worm.Win32.Scano.gen, Email-Worm.Win32.Nyxem.e, Email-Worm.Win32.NetSky.b, Net-Worm.Win32.Mytob.t