According to Symantec a new variant of the beagle mass mailing worm was released. The new worm (B) spreads via email as an EXE file named at random. Once executed the worm listens on port 8866 for uploads of code to be executed on your system.
See Symantec's report for more information
Topsight.net
http://www.topsight.net/article.php/20040217184753458