More Than 97% of all e-mails sent are un-solicted and unwanted according to Microsoft

The e-mails are dominated by spam adverts for drugs, and general product pitches and often have malicious attachments.

The report found that the global ratio of infected machines was 8.6 for every 1,000 uninfected machines.

Paul Wood, senior analyst at e-mail security firm Message Labs, said he was surprised the Microsoft figure for unwanted e-mail was so high. “Our own analysis shows that around 81% of e-mail traffic we were processing was identified as spam and unwanted,” he said.  MessageLabs said spam rates had fallen at the end of 2008 as an ISP which had been hijacked to send out spam mails to users had been taken offline. “As a result of that, a number of developers in botnet technology at the end of last year were trying to regain botnet control and increase capacity and return to previous spam levels.

“It won’t be far off before we see return to those levels. “The report, which looked at online activity during the second half of 2008, also pinpoints the countries that are suffering from the most infections of malicious software, or malware. Russia and Brazil top the global chart of infections, followed by Turkey and Serbia and Montenegro.

It said that the type of malware varied from country to country. “As the malware ecosystem becomes more reliant on social engineering, threats worldwide have become more dependent on language and cultural factors,” it reported.

In China, several malicious web browser modifiers are common, while in Brazil, malware that targets users of online banks is more widespread. In Korea, viruses such as Win32/Virut and Win32/Parite are common.

Global average

The global average for infected machines is 8.6 for every 1,000 uninfected PCs. The UK’s infection rate is 5.7, according to the Microsoft report. The report highlighted the need to keep operating systems, web browsers and applications up to date with the latest versions.Increasingly, hackers are using common file formats, such as Microsoft Office documents and Adobe’s PDF format as the carrier of malicious exploits or programs. More than 91% of attacks exploiting vulnerabilities in Microsoft Office were using security holes that had been plugged by updates that had been available for more than two years. Attacks using PDF files rose sharply in the second half of 2008, the report noted. The vulnerabilities all of the attacks exploited had already been fixed by Adobe, and were not present in the most recent versions of the software. Mr Gibson told BBC News people had to be aware that if they did not update their applications, such as Office and Adobe, they were not just putting themselves at risk, but others on the internet also. “If you don’t update your software you are not just a hazard to yourself, you are hazard to others because you can be part of a botnet [if your computer is hijacked].” Mr Evans said Microsoft was very happy with the approach consumers were taking to updating applications via automatic updates. “For consumers it is happening but for business less so. We have encourage businesses to make more use of automatic updates.”