But the number of trojans and worms – more sophisticated and largely geared for financial gain -- remained high, according to a company statement. The number of known viruses, meanwhile, has dropped as lawmakers crack down on computer crime, the company said.
"Viruses...have reached rock bottom this year," Luis Corrons, director of PandaLabs, said. "The aim of creators of this type of threat is usually fame...Now, almost nobody runs the risk if does not lead to financial gain."
Of the new threats detected last year by PandaLabs, 42 percent were trojans, 26 percent were bots, 11 percent were backdoor trojans, 8 percent were dialers, 6 percent were worms and 3 percent were versions of adware and spyware.
The number of new malware threats rose by 48 percent last year, anti-virus giant Sophos has said.
The Sophos Security Threat Management Report 2005 revealed in December that on average, one in every 44 emails was viral during 2005. That statistic rose to one in 12 during major outbreaks, while 15,907 new malware threats were identified.
According to an analysis from security firm F-Secure, this steep increase in overall number of viruses was accompanied by a fall in the severity of mass assaults using network worms. The study noted that there were only two major outbreaks during the last six months of 2005: one in September, with the Zotob worm, and the second, Sober-Y, in late November.
The F-Secure report observed that 2005 was also characterized by a spate of criminal phishing attempts, either directly to online banking customers yielding high profits to the malware authors, or by exploiting man-made and natural disasters.