On Thursday, MessageLabs reported in its April Intelligence Report a marked decrease in the number of malware links connected to the Storm botnet. "It's not too often that a security company says that things are getting better," said Mark Sunner, Chief Security Analyst.
At its peak, Sunner said, the Storm botnet resided upon one million computers worldwide. That number has since come down to between 85,000 IP addresses at the end of April. He said that over the last eighteen months Storm has been constant, and never decreased according to MessageLabs research. "Other security companies have reported decreases in the past," he said because of different methods of studying the botnet, "but this is first decrease we've seen."
He credited the most recent patches from Microsoft with the decline. He said that in the weeks following the most recent Patch Tuesday there was a sharp drop off.
Given that the creators of Storm managed and maintained a constant flood of variations for more than one year, it's a little odd that they would just take their money and walk away. Sunner said that they are seeing an increase in Srizbi, named for the one of the Web sites from which is downloaded. A Trojan, Srizbi uses rootkit technology to hide on an infected machine but, like Storm, it is also known to relay spam.