Last month Trend Micro, the anti-virus firm, recorded a six-fold increase in malware compared to September 2003. It detected 1,485 new items of malware last month, compared to 250 new types of malicious code in the same period last year.

TrendLabs attributes the increase in malware to a change of motives among virus writers. Previously VXers were looking for their 15 minutes of fame; but now they are more interested in making money. Trend points to the increased prevalence of malicious code designed to create 'zombie' networks, also called botnets. These can be auctioned off to the highest bidder to execute denial of service attacks or to use as spam relays. TrendLabs has seen successive releases of information-stealing trojans which try to obtain personal information, such as bank details, from infected users.

TrendLabs reports that 'Trojans' now account for 61 per cent of all malware detected; 79 per cent of worms in September were 'bots'. This is a significant jump from last year - when only 17 bots were detected, compared to more than 400 between 25 August and 25 September 2004.

Trend also records the emergence of the first JPEG virus in September, and notes that the most damaging variant of the Sasser worm - Sasser-B - is still prevalent four months after its first appearance in the wild. ®

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