'Critical' Windows security flaws eyed

SAN FRANCISCO-- Microsoft Corp. warned users of its Windows operating system on Tuesday of three newly found "critical" security flaws in its software that could allow attackers to take complete control of a computer.

The world's largest software maker issued patches to fix the problems as part of its monthly security bulletin. The problems mainly affect the Windows operating system and Microsoft's (down $0.05 to $24.41, Research) Internet Explorer Web browser.

Computer security experts urged users to download and install the patches, which are available at www.microsoft.com/security .

"Symantec recommends that users apply the updates as quickly as possible and refrain from opening unknown attachments or clicking on suspicious links that arrive via e-mail or instant messages," said Oliver Friedrichs, senior manager at security software company Symantec Corp. (down $0.09 to $22.06, Research)

Microsoft said one vulnerability exists in its Internet Explorer Web browser, which an attacker could exploit to take over a PC by running software code after luring users to malicious Web pages.

Other possible attacks taking advantage of "critical" security flaws in the Windows operating system could come through opened mail attachments.

Microsoft also issued four security warnings it rated at its second-highest level of "important" and two other bulletins it classified as "moderate."

For more than three years, Microsoft has been working to improve the security and reliability of its software as more and more malicious software targets weaknesses in Windows and other Microsoft software.

[inline:1]More than 90 percent of the world's personal computers run on the Windows operating system.