Figures compiled by Sophos's global network of monitoring stations show that infected web pages continue to pose the biggest threat.
On average last month, Sophos uncovered 9,500 new infected web pages daily - an increase of more than 1,000 every day when compared to April. In total, 304,000 web pages hosting malicious code were identified in May.
The top 10 list of web-based malware threats in May 2007 reads as follows:
- Mal/Iframe 65.5%
- JS/EncIFra 6.9%
- Troj/Decdec 6.5%
- Troj/Fujif 3.7%
- Troj/Ifradv 3.0%
- VBS/Redlof 2.2%
- Mal/ObfJS 1.8%
- Troj/Psyme 1.2%
- VBS/Roor 1.0%
- VBS/Soraci 0.9%
Iframe, which works by injecting malicious code onto legitimate web pages, continues to dominate the chart, accounting for almost two thirds of all web-based threats in May.
The three newcomers, Redlof, Roor and Soraci, are all appending viruses, infecting, amongst others, HTM, HTML and HTT files.