Not really a "new" threat: a "rootkit" is a set of tools that allow access to a computer using "root" privileges. "Root" is the account on all Unix boxen that has total control over a computer. Anyone that has "root access" can change anything anywhere on that computer. Recently, Sony has been using a "digital rights management" (DRM) technique that installs what is essentially a rootkit on any windows-based PC that plays some of their CDs. Needless to say, the outcry over this has been quite loud. This morning, while reading a post over at Slashdot, about another threat to instant messaging clients, I thought it might be good to bring rootkits to your attention thinking that "forewarned is fore armed". In the above linked story, there is a link to an article entittled Santa IM worm hits AOL, MSN and Yahoo published on ZDNet. This article links to another article at the same site entitled What makes a rootkit? Quoting from this article: F-Secure's site has more information about rootkits and the Sysinternals site has a rootkit resource list at the bottom of the page.