Virus Top 20 November 2005

1 – Net-Worm.Win32.Mytob.c 18.25%
2 – Email-Worm.Win32.Doombot.b 8.11%
3 – Email-Worm.Win32.Zafi.d 7.61%
4 – 6.03%
5 – Email-Worm.Win32.LovGate.w 6.02%
6 – 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 – Net-Worm.Win32.Mytob.bk 2.50%
10 +4 Net-Worm.Win32.Mytob.u 2.36%
11 Re-entryNet-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 1.79%
15 -4 Net-Worm.Win32.Mytob.y 1.69%
16 New Email-Worm.Win32.Doombot.g 1.52%
17 – Email-Worm.Win32.Bagle.dx 1.50%
18 -3 Email-Worm.Win32.Zafi.b 1.40%
19 Re-entryEmail-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 20 leader in
November, the picture for 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 1st place. Due to
its prevalence, Mytob can be 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
position. In November, there were ‘only’ 9 variants in our Top 20. Of
course, no other virus families have even come close to such ratings,
but remember it’s not so long ago 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 was 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 that I was mistaken. 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 to bring 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 favorite, 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 skillful
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 via file-sharing 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 November 16th and caused one of the most
widespread 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 was
detected in mail traffic, highlighting the fact that a large number of
worms and Trojans not listed in our rankings are still circulating.

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