The virulent MyDoom.b worm's attack on is beginning to gather strength, reports mi2g.

The worm was programmed to begin attacking the software giant's site February 3. Though that date passed with no discernible Distributed Denial of Service (DDoS) attack, the assault has gathered strength over the weekend, the security consultants revealed this morning.

"Microsoft's site has been intermittently inaccessible on a few occasions from major North American, European and Asian cities on Saturday and Sunday as MyDoom continued to spread relentlessly and MyDoom.b upgraded MyDoom.a infected machines," mi2g warns.

The consultants explained: "As of 10:30 GMT, the Microsoft Web site's time to download the home page has been dilating very fast from less than half of one second to well over 2.5 seconds as an average, as measured from London and other world cities. Provincial cities are reporting worse dilations."

mi2g executive chairman DK Matai warned: "MyDoom is still out there and spreading.  It has picked up momentum in the last 48 hours once again.  This is a dangerous global epidemic.  There are over a million computers still infected that have their backdoors open and they are being upgraded to MyDoom.b which targets Microsoft."

The MyDoom.b attack is designed to last up until the 1st of March. Matai warned: "This is not yet over."