Total malware volumes grew "dramatically" during the first three months of 2007 as the majority of malicious code writers began targeting the web, new research warned today.

Sophos identified 23,864 new threats in the first quarter of 2007, more than double the 9,450 found in the same period last year.

At the same time, the percentage of infected email dropped from 1.3 per cent, or one in 77 emails, in the first three months of 2006, to one in 256, or just 0.4 per cent, in 2007.

Sophos identified an average of 5,000 new infected web pages every day from January to the end of March, indicating that this route to infection is becoming more popular with cyber-criminals.

As computer users become increasingly aware of how to protect against email-aware viruses and malware, hackers have turned to the web as their preferred vector of attack.

The top 10 malware families hosted on websites in the first quarter of 2007 were as follows:

1. Troj/Fujif 50.8%
2. Troj/Ifradv 12.1%
3. Troj/Decdec 10.4%
4. Mal/Packer 6.3%
5. JS/EncIFra 5.5%
6. Mal/FunDF 2.3%
7. Mal/Psyme 2.2%
8. Troj/Zlob 2.0%
9. Mal/Behav 1.2%
10. Mal/DelpBanc 0.4%
Others 6.8%

Sophos reported that not all of the infected websites were created by the hackers themselves.

Some 70 per cent were bona fide websites that were vulnerable to attack because they were unpatched, poorly coded or had not been maintained by their owners.

A further 12.8 per cent were hosting malicious scripts, while Windows malware was responsible for infecting 10.7 per cent. Adware was found on 4.8 per cent of these pages and porn diallers on 1.1 per cent.

The most high profile website infection of the quarter happened in February when hackers placed malicious script, identified as Mal/Packer, on the official Miami Dolphins website.

The American football team was due to host the Super Bowl the weekend after this happened, so its site was an extremely popular destination for web surfers at the time.