A new vulnerability in Microsoftis Internet Explorer Web browser has been found, and itis technically being described as a "doozy." C|Net is reporting that Foundstone, a security company, found a flaw that could affect millions of PCs running pre-XP versions of Microsoftis Windows OS, including Windows 2000. From the C|Net article titled Millions vulnerable to Microsoft Web flaw:

The vulnerability, found by security company Foundstone and confirmed by Microsoft, could allow an Internet attacker to take over a Web server, spread an e-mail virus or create a fast-spreading network worm.

"There are millions of systems and clients that will be affected by this," said George Kurtz, chief executive of Foundstone. "This is huge." Foundstone originally discovered the flaw and worked with Microsoft to develop a patch.

The flaw, in a component of Windows that allows Web servers and browsers to communicate with online databases, could be as widespread as the flaws that allowed the Code Red and Nimda worms to spread, said Kurtz. It likely affects the majority of the more than 4.1 million sites hosted on Microsoftis Internet Information Service (IIS) software. In addition, millions of Windows 95, 98, Me and 2000 PCs could also be vulnerable to the software bug.

Microsoft rated the flaw as critical under its new vulnerability evaluation system that is intended to lessen the number of flaws that receive a "critical" rating to help administrators identify the most important vulnerabilities to patch.

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Windows computers, except those running Windows XP, are also vulnerable if Internet Explorer 5.01, 5.5 and 6 are present, as they also use the data access component. However, attacks on such systems are harder to accomplish, Terwoerds said. Outlook Express 6 and Outlook 2000 are immune to attack in their default configurations, and other versions of the mail client can be made safe by using the Outlook E-mail Security Update, she said.

The article goes to say that Microsoft has posted a security warming along with instruction on how to secure servers that could be affected. More information is available in the full article and, if you own or manage Windows based PCs, we suggest that you take a read.