Cousins said Sophos is in a "unique" position to offer this kind of service because it operates integrated spam and anti-virus labs that are rivaled by Symantec. Sophos has detected spam masquerading as viruses and vice-versa, he added.

Sophos has done trials in some universities in Asia Pacific and the results reveal high incidence of hijacked PCs. "What we found out in some of our trials in some universities is there are PCs within their network hijacked by U.S. spammers sending out spam," Cousins said.

A recent study by Symantec revealed that the number of bot-infected computers in the first half of this year increased by more than 14 percent from the same period last year. Seoul, Beijing, and Taipei are ranked among the top 10 cities worldwide with the most number of zombie computers.