Two thirds of spam originates from computers infected by viruses such as Sobig-F, according to MessageLabs.

The email filtering firm blames Sobig-F, the world’s fastest spreading virus for a rise in both spam and viruses in 2003.

At its peak, one in every 17 emails stopped by MessageLabs contained a copy of Sobig-F. By December 1, more than 32 million emails containing the virus had been stopped by MessageLabs, making Sobig-F the biggest viral nuisance this year.

The ratio of spam to email this year is one in 2.5, compared with one in 11 a year ago, according to MessageLabs. Meanwhile, the ratio of viruses to email in 2003 is one in 33, compared with one in 212 a year ago. This is a record high for both viruses and spam.

According to MessageLabs, spam and viruses techniques are converging to “steal identities, defraud consumers and create hidden networks of infected consumers to send spam”.

Sobig-F is a classic example of a convergence between spam and virus writing techniques, says Mark Sunner, CTO, MessageLabs: “The convergence of virus and spam techniques has led to a much more sophisticated threat – the impact of which many firms have yet to grasp.

“Sobig sought not only to infect a machine and propagate further through mass mailing techniques, but also to compromise systems by exploiting open proxies. This backdoor route means that an infected PC can be turned into a spam engine."

MessageLabs’ End of Year Report, also notes a huge increase in phishing scams. Customers of NatWest, Citibank, Barclays, Lloyds TSB and eBay have all been targeted in scam emails in the last two months alone.

The Mimail-J virus was used to try to dupe PayPal users into handing over confidential financial information. ®

Top 10 Viruses of 2003, according to MessageLabs

• Sobig-F (32,432,730)
  
• Swen-A (4,184,129)
  
• Klez-H (4,006,766)
  
• Yaha-E (1,920,424)
  
• Dumaru-A (1,129,061)
  
• Mimail-A (1,052,481)
  
• Yaha-M (862,682)
  
• Sobig-A (842,729)
  
• BugBear-B (814,865)
  
• SirCam.A (511,578)