Win32/Conficker.A, an internet worm, is now in the wild and infecting PCs across the globe. The worm exploits a critical vulnerability in Microsoft Windows systems, although Microsoft released a patch for the security hole in October.
The way the worm works is that it opens a random port between 1024 and 10000 and operates as a web server. It then spreads itself to other computers using the exploited Windows security hole.
Although most of the infected systems have been in the U.S., computers in several other countries continue to be infected and spread the worm in both corporate and home environments. There are a number of other bots that use the same exploit.