The word on the street is that there is a rise of Windows computer systems infected due to the Win32/Conficker.B (a.k.a. “Downadup”) worm. Microsoft addressed this issue (MS08-067) in October 2008, as did other anti-virus vendors, but there are quite a number of unpatched, vulnerable systems in the wild.

This vulnerability affects Windows 2000, XP, and Vista; and Windows Server 2003 and 2008. Attacked systems may lock out users, disable update services, and block access to security related websites. That’s a serious matter. Don’t become a victim!

What you should do.

Earlier this month, Microsoft updated their Malicious Software Removal Tool (MSRT) to help remove variants of Win32/Conficker. Download and run this tool.

If you regularly update your Windows system, either with Automatic Updates or manually applying Windows Updates, chances are you are fine. Run the most recent MSRT anyway, for your own peace of mind.

If you run Windows operating systems, turn on the Automatic Updates. You can control if updates are applied automatically or prompt to be run. If you are inside an IT-savvy organization, they may push these updates out to your machine already. If you absolutely can’t live with automatic download of updates, then add a recurring task to your calendar to check for and apply updates manually. I’d suggest doing it once a week.

Run a commercial-grade anti-virus product, and keep its malware definitions up to date.

If you want more information about this specific threat, including manual steps to remove it from your system, read this Microsoft Knowledge Base article: Virus alert about the Win32/Conficker.B worm.