Virus Top Twenty for November 2005

Position	Change in position	Name	Percentage
1.	0	Net-Worm.Win32.Mytob.c	18.25
2.	0	Email-Worm.Win32.Doombot.b	8.11
3.	0	Email-Worm.Win32.Zafi.d	7.61
4.	0	Net-Worm.Win32.Mytob.bi	6.03
5.	0	Email-Worm.Win32.LovGate.w	6.02
6.	0	Email-Worm.Win32.NetSky.q	4.15
7.	+1	Email-Worm.Win32.NetSky.b	3.73
8.	+2	Net-Worm.Win32.Mytob.t	3.17
9.	0	Net-Worm.Win32.Mytob.bk	2.50
10.	+4	Net-Worm.Win32.Mytob.u	2.36
11.	Return	Net-Worm.Win32.Mytob.h	2.16
12.	+1	Net-Worm.Win32.Mytob.q	2.15
13.	New	Email-Worm.Win32.Sober.y	1.99
14.	Return	Net-Worm.Win32.Mytob.bt	1.79
15.	-4	Net-Worm.Win32.Mytob.y	1.69
16.	New	Email-Worm.Win32.Doombot.g	1.52
17.	0	Email-Worm.Win32.Bagle.dx	1.50
18.	-3	Email-Worm.Win32.Zafi.b	1.40
19.	Return	Email-Worm.Win32.NetSky.y	1.12
20.	-13	Email-Worm.Win32.Doombot.d	1.09
Other malicious programs			21.66

The penultimate month of the year is always important for our end of year statistics. As a rule, if there isn’t a new Top Twenty leader in November, the picture of the outgoing year is almost complete – no matter what happens in December, it won’t have an effect on the distribution of malicious programs as a whole.

November 2005 was unique for its stability. The six worms which lead the ratings in October retained their places. The stability is all the stranger given November’s virus epidemic, which should have caused changes in the distribution at the top of the table. However, this didn’t happen – I’ll explain why below.

Mytob.c is still leading the ratings and has increased its lead, adding almost another four percent. We can already say with certainty that one of the Mytobs will be ‘worm of the year’ – this is thanks to the number of times that a member of the Mytob family has taken first place. Due to its prevalence, Mytob can viewed as the biggest epidemic of 2005 and it can be ranked with viruses such as Sobig (2003) and NetSky (2004).

Overall, however, worms from the Mytob family are relinquishing their hold. In November, there were ‘only’ 9 variants in our Top Twenty. Of course, no other virus families have even come close to such ratings, but remember it’s not so long ago that that Mytob occupied 13 places out of 20. This indicates that Mytob’s dominance is weakening.

In October two malicious programs appeared in the ratings – Doombot.b. and Doombot.d. It seemed that they might have been able to compete with Mytob and to squeeze out other worms. Doombot.b climbed quickly into second place during the first two weeks of October, and Doombot.d made it into 7th place in only a week. Doombot is functionally almost identical to Mytob, and consequently were fighting for the same turf, but Doombot spread more quickly. In October, I predicted that Doombot.b might lead the ratings in November.

But it seems I was wrong. Doombot.b is still in 2nd place, and has lost 2%, while Doombot.d is on the verge of leaving the ratings, having sunk 13 places, leaving it bringing up the rear.

And in spite of the fact that we have a new Doombot representative in the ratings (Doombot.g at 16th place) it seems that this family is not going to have a significant influence overall.

As can be seen, there are only two newcomers to our table. We’ve already mentioned Doombot.g, so let’s turn our attention to 13th place, which is occupied by a new variant of our old favourite, Sober. This worm’s history started two years ago, in October 2003, and since then almost every new variant has had a significant influence on the epidemiological condition of the Internet. The epidemics caused by Sober.e and Sober.c have been among the most notable during recent years.

As a rule, Sober targets Internet users in Western Europe. The worm’s author uses his/ her creation to publicize political views, and uses some very effective social engineering tricks. And it’s due to the skilful use of social engineering that new Sober variants pose such a threat.

Sober.y used an old approach – the message it sent appeared to come from the FBI, informing the user that s/he had violated copyright by downloading music from filesharing networks. The message tells the user to open the attachment, which allegedly contains data relating to the offence. An interesting point is that the message included a direct line telephone number for the FBI. Many users who received the messages sent by Sober.y rang the FBI, resulting in what one could call a DoS attack on the FBI’s phones.

Another interesting Sober fact is that the Bavarian police issued a warning about the new variant before it was actually detected. This makes us think that law enforcement bodies are currently actively tracing the author, and it may be that there will be news of an arrest in the very near future.

Sober.y was detected on 16th November and caused one of the most major epidemics in 2005 in Western Europe. The fact that Sober.y only reached 13th place in our ranking can be explained by the fact that our statistics are composed using data mainly from Russian mail servers; although infected messages were sent in Russia, the number was relatively small.

A significant percentage (21.66%) of other malicious programs were detected in mail traffic, highlighting the fact that a large number of worms and Trojans which are not listed in our rankings are still circulating.

Summary: