Analysis shows that during April, the Storm botnet has dramatically decreased to just five percent of its original size, while web-based malware has increased by 23.3 percent. The introduction of new malicious software removal tools, which are aimed at targeting and removing Storm infections, are deemed responsible for the sudden reduction in Storm-infected machines, now estimated at approximately 100,000 compromised computers.
Previously estimated at two million, the decline in Storm’s botnet size is evident by the 57 percent decrease in malware-laden emails distributed by the Storm botnet during April.
While the Storm botnet decreased in size, analysis of web-based malware identified that 36.1 percent of interceptions in April were new, an increase of 23.3 percent since March. MessageLabs also identified an average of 1,214 new websites per day harboring malware and other potentially unwanted programs such as spyware and adware, an increase of 619 per day compared with the previous month.
Source: MessageLabs Intelligence Report for April 2008.