A computer worm or virus, called Conficker or Downadup; the most severe outbreak in years, continues to spread after infecting millions of corporate computers and server machines.

According to preliminary estimates these signs that first appeared in middle October or first week of November has recently become more prevalent.

The worm, which can block users from accessing their accounts, also spreads through portable storage devices; it's spreading through memory sticks, unsecure networks and PCs that haven't been updated with the newest security updates.

Many antivirus software company are still wandering why the worm hasn't yet activated since it's already spread to almost 6% of computers around the world. The clock is running, many virus researchers are looking at some point that the Downadup maker already had in mind to trigger the switch anytime.

They've obviously put a lot of thought into the worm. They've been very methodical, Alfred Huger vice president of development at Symantec Corp.'s security response group said in a statement This is a very well-engineered piece of software

Ryan Sherstobitoff, chief corporate evangelist for Panda Security says, We think this is a wide-scale distraction to hide data breaches, it does not appear in the variants of Conficker that they are building a botnet, but that wouldn't surprise us, either. This is an attack we have not seen in some time and is certainly a warning sign for something more to come

Researchers remained worried about the next step in the attack and remained worried about the next step in the attack.

To those who are using Windows OS, Microsoft released a patch for the security flaw exploited by Downadup in October. Customers who think they have the worm can also download the free Malicious Software Removal Tool at http://www.microsoft.com/security/ malwareremove/default.mspx, according to a Microsoft statement.