The first half of 2007 saw a huge rise in the number of Web-based security threats, overtaking the number of attacks by e-mail.

A report by security experts Sophos identified a sharp rise in the number of web threats in the first half of 2007, which have now overtaken e-mail as the preferred method for cybercriminals.

In June alone around 29,700 infected web pages were identified each day. At the start of 2007, the number was just 5,000 per day.

Sophos also found that four in five of these dangerous web sites were actually legitimate sites that had been hacked or infected with malicious code.

Most malware-infected web pages are hosted in China, which has now overtaken the US. In the first six months of 2007 China was responsible for hosting over half of all web threats reported to Sophos.

Cybercriminals have also been finding ways to avoid spam detection programs by using PDF file attachments and graphics to spread their messages rather than normal text.

Infected removable flash drives have also been increasingly used to spread viruses.

PC users are advised to keep their security software and Windows updated, and not to click on links in unsolicited e-mails.

Sophos Security Report July 2007

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