Hacking tools head up the list of malware detected on computers around the world, according to figures released by Microsoft at Infosecurity Europe 2007.

"Backdoors, key-loggers, downloads and droppers continue to be the main malware menaces we're seeing in the marketplace," said Nicholas McGrath, head of platform strategies Microsoft.

Data collected from Microsoft's security software between July and December 2006 showed that attacks were much more likely to target individual machines.

"The exploits are very much targeted at the individual, either by taking their identity to gain from something like their credit card, or taking control of the PC to build their own botnets to be used in organised criminal activities," said McGrath.

The figures were collected from Microsoft's Malicious Software Removal Tool (MSRT) released in January 2005.

"MSRT is now running on 310 million computers, and over 18 million computers are also running Windows Defender," said McGrath.

McGrath claimed that the latest figures show that improvements in Windows XP had led to a reduction in the amount of malware affecting PCs.

"With XP Gold there were many more instances where the software tool had to run, in comparison to Windows XP with Service Pack 1, and the same with Windows XP Service Pack 2," he said.

"It is a great testimony to the engineering work we have been doing to change some of the fundamental architectural aspects of the operating system to make it more difficult for malware to infect the machine unless through things like social engineering."

McGrath was also encouraged to see that 94 per cent of machines are running Windows XP with Service Pack 2, showing that users are taking security seriously.

Microsoft hopes to reduce the spread of malware even further by targeting it internationally, using localised versions of the security software.

"In the US and the UK, where we have already had Windows Update and Automatic Update and Windows Defender and technologies such as Windows OneCare, the number of incidences where we have detected malware has actually dropped dramatically in those countries," said McGrath.

"When we release and bring new versions of our products online in local languages, as in Germany and Japan, the numbers are quite high on the chart. We are anticipating that over time the number of infections will actually decrease. "