There has been a "troubling" rise in virus activity across Europe, the Middle East and Africa, according to the latest findings from Trend Micro, the anti-virus firm.
There were some 1,485 new malwares in September compared with only 250 new malicious codes for the same period last year.
Trojan programmes accounted for 61 per cent of the malware detected (including backdoors, which are basically remote Trojans) and worms accounted for 29 per cent.
More strikingly, 79 per cent of the worms in September are bot programmes, reflecting the expansion of remotely controlled zombie networks.
"There is evidence of a clear motivational shift in the creation of viruses. Whereas previously virus writers were looking for their 15 minutes of fame, it would now seem that their inspiration is based on earning profits and monetary reward," the report said.
"This is illustrated by the growing number of malicious codes designed to create zombie networks, which can be leased at any time to the highest bidder, as well as the successive releases of information-stealing Trojans, like variants of TROJ_BANKER and TROJ_BANCOS, which attempt to steal sensitive information (such as bank account details) from infected users.
"The increased availability of malware source codes on the Internet is another significant factor, allowing hackers to create new variants by modifying the code, which are then released into the wild.
"This is particularly the case with worms like Mydoom, Bagle and Lovgate."
The data also found that four months after its release into the wild, SASSER.B is still one of the Top 10 viruses listed by prevalence by TrendLabs.
Last month, Sasser accounted for 31 per cent of the total number of infections in this list with most sightings of the worm coming from India.
"This would indicate that there is still a large number of systems that still remain un-patched against the vulnerability in question despite repeated campaigns from all sectors of the security industry."