Sophos: Top 10 Viruses and Hoaxes in August 2003

Sobig-F wins the ‘war of the worms’

This is the latest in a series of monthly charts counting down the ten most frequently reported viruses and hoaxes as compiled by Sophos, a global leader in anti-virus protection for businesses.

For August 2003, the chart is as follows, with the most frequently occurring virus at number one:

1. W32/Sobig-F (Sobig variant) 37.6% New Entry
2. W32/Blaster-A (Blaster worm) 18.8% New Entry
3. W32/Nachi-A (Nachi worm) 5.5% New Entry
4. W32/Mimail-A (Mimail worm) 5.3% New Entry
5. W32/Yaha-P (Yaha variant) 2.1%
6. W32/Klez-H (Klez variant) 1.3% 19 months in chart
7. W32/Bugbear-B (Bugbear variant) 1.1%
8. W32/Yaha-E (Yaha variant) 0.8%
9. W32/Dumaru-A (Dumaru virus) 0.6% New Entry
10. W32/Sobig-A (Sobig worm) 0.3%

Others: 26.6%

“August 2003 will be remembered as one of the worst months in the history of computer security. A series of different viruses have bombarded computer systems around the globe, culminating in the newest member of the Sobig family which swamped internet email traffic and took the pole position in the chart. The top four viruses are all new entries – any of which would have been number one in a normal month,” said Graham Cluley, senior technology consultant at Sophos Anti-Virus. “The Sobig-F worm clogged up inboxes and crippled networks with the sheer volume of email traffic it produced. Users and companies should remain on guard and put systems in place to protect against future attacks.”

Sophos analysed and protected against 778 new viruses in August. The total number it now protects against is 84,277.

The top ten hoaxes reported to Sophos during August 2003 are as follows:

1. Hotmail Hoax 16.3%
2. JDBGMGR 12.2%
3. Bill Gates Fortune 10.8%
4. WTC Survivor 7.9%
5. Meninas da Playboy 7.4%
6. Bonsai Kitten 4.7%
7. Budweiser frogs screensaver 3.8%
8. A virtual card for you 3.2%
9. Frog in a blender/Fish in a bowl 3.1%
10. Bill Gates 1.3%

Others: 29.3%

“Bill Gates seems to be a target for hoax writers and virus writers alike. While the Blaster worm capitalised on a flaw in Microsoft’s software and attempted to knock one of their websites off the internet, two hoaxes about Bill Gates are still circulating.” continued Cluley.

Sophos has made available a free, constantly updated information feed for intranets and websites which means users can always find out about the latest viruses and hoaxes:

Graphics of the above Top Ten virus chart are available at

For more information about safe computing, including anti-hoax policies, please visit:>

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