The malicious software, also known as Downadup or Kido, is a self-replicating program that takes advantage of networks that haven't kept up to date with security patches for Windows RPC Server Service. Microsoft issued a patch update, but if the patch has not been installed or if an infected USB memory stick is used, only anti-virus software can keep a computer safe. Once in a computer, the worm digs deep and sets up defenses that make it difficult to extract. Malware could be triggered to steal data or turn control of infected computers over to hackers seeking to create a "botnet."
The bottom line: Make sure your anti-virus software is up to date and that you have installed Microsoft's MS08-067 patch, which is known as KB958644.