The most newsworthy event related to viruses and worms last month was the emergence of the Slammer worm, which infected tens of thousands of Windows systems throughout the Internet on January 24 and 25. This worm exploited vulnerabilities in the Resolution Service of Microsoft SQL Server 2000, sometimes causing unauthorized code to run on victim systems and also making infected machines unresponsive. Turning off the MSSQLServer service is the best preventative measure, but if you need to run this service, installing a Microsoft patch will prevent your system from being infected by this nasty worm. Read more about the Slammer worm.

Last month, a total of 6,222 viruses and worms tried unsuccessfully to make their way through the LBNL virus wall. The most prevalent type of virus/worm was the Klez.H worm, with 4,731 instances detected and eradicated, followed by the Yaha.G worm with 635 instances. The Sobig.A worm came in third with 187 instances. Each of these Windows-based worms is by no means new and you can read more about each of them.