Sober worm tops May viral charts

The new Sober-N worm, which poses as offers for free tickets for the 2006 World Cup, toppled Zafi-D as the most popular, sorry, prevalent virus on the internet last month.

Zafi-D, showing the sort of chart topping success that record industry execs would give their right nostril for, spent five straight months in the top spot before it was finally knocked off its perch in a chart compiled by anti-virus firm Sophos.

The bilingual Sober-N worm was detected at the beginning of the month and rapidly spread across 40 countries. Windows PCs infected with the worm were later used as a launch pad for a spamming campaign. The spam subject lines included 'Dresden Bombing Is To Be Regretted Enormously', 'Armenian Genocide Plagues Ankara 90 Years On', 'Dresden 1945' and 'Turkish Tabloid Enrages Germany with Nazi Comparisons'.

A mass mailing worm accompanied by a backdoor Trojan, MyTob-AZ, was the other new entry of Sophos's May charts, coming in at number six. Sophos identified and protected against 1,515 new viruses in May. The total number of viruses Sophos now protects against is 104,784. Its research shows that 2.62 per cent of emails circulating in May 2005 were viral, slightly up on April 2005.

By contrast security appliance firm Fortinet reports a 20 per cent decrease in virus prevalence last month compared to April. Of the new malicious codes detected by Fortinet in May 2005, approximately 33 per cent were Trojans (including backdoors), 33 per cent were network worms (worms which propagate through the network via exploits, networks shares and Instant Messengers), and 2 per cent were mass-mailing worms.

Incidents of new Trojans dropped 3 per cent over the course of last month, following a 20 per cent decrease from March-April). This brings the overall percentage of Trojans detected in May to pre-February levels, according to Fortinet. Most virus writing activity focused on the creating of bots, malicious code capable of commandeering infected PCs. ®

Top 10 computer viruses, according to Sophos

1. Sober-N
2. Zafi-D
3. NetSky-P
4. NetSky-D
5. Zafi-B
6. MyTob-AZ
7. MyTob-Z
8. NetSky-Z
9. MyTob-E
10. NetSky-N

Related stories

Sober worm shakes Windows security
Sober infected PCs spew right-wing 'hate spam'
The strange decline of computer worms
Undead worms infest Windows PCs (again)