“Microsoft Corp. appeared to outfox the creators of a computer worm that last week infected hundreds of thousands of computers, limiting additional damage,” wrties Robert Guth in today’s Wall Street Journal.

“The spread of the so-called Blaster worm appeared to slow over the weekend. Blaster failed to harm a Microsoft Web site it was programmed to attack after the company redirected computer traffic away from the vulnerable site.”

“A computer worm is a short computer program that spreads on its own over the Internet, causing computers to break down. The Blaster worm, also known as ‘LoveSAN’ and ‘MSBlast,’ had been designed to send a flood of messages beginning Saturday to the Web site where Microsoft typically posts fixes, or patches, for software flaws. The attack was apparently an attempt to cripple the site and make it more difficult for users to protect their computers against the Blaster worm.”

“But Microsoft on Friday changed the way it routes computers to the site, averting the attack. The patch for the Blaster worm is now available at http://windowsupdate.microsoft.com.”

“The Blaster worm, which surfaced early last week, exploited a flaw in Microsoft’s Windows 2000 and Windows XP operating systems that allows the worm to enter a PC over the Internet and then spread by searching the Internet for other PCs with the same flaw. Computer users reported that the worm caused their machines to shut down repeatedly.”

“Microsoft issued a software patch for the flaw July 16, but many computer users hadn’t installed it. Since last week, makers of computer antivirus software have been distributing software that can guard against the worm and rid infected PCs of it. Despite the worm’s slowed pace, security experts said Blaster could still wreak havoc on unprotected computers.”

“Estimates vary as to how many computers world-wide were infected by Blaster, from 350,000 to more than one million. Security experts say they expect the total number of infected computers to continue rising, as computer users return to work in places such as Japan, where many businesses last week were shut for a summer holiday.”