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Robert Vamosi
Senior editor

CNET Security Center: Your complete source of antivirus and Internet security information.

Internet Explorer JavaScript Windows () flaw prevention and cure
Only a workaround exists to keep this JavaScript flaw from crashing your PC.
By Robert Vamosi (November 29, 2005)

QUICK FACTS
Name: IE Active Scripting flaw (CAN-2005-1790)

What it does: Allows an attacker to run code remotely on a victim's computer

Means of transmission: Malicious code on a Web site or HTML e-mail

How to recognize: HTML code that uses the Windows () command

Who is at risk: Users of Internet Explorer 5.x and 6.x

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Several security companies have reported the existence of code designed to exploit a known flaw in Microsoft Internet Explorer 5.x and 6.x. Although not a virus or a worm, the malicious code could allow a remote attacker to crash your PC after visiting a compromised Web page. First reported on May 31, 2005, by Benjamin Tobias Franz, the Internet Explorer JavaScript Windows () flaw has not been patched by Microsoft, although a workaround does exist.

How it works
According to the security vendor Secunia, the flaw lies within the JavaScript component of Internet Explorer. Whenever a user attempts to render a Web page coded with a compromised Windows () function, used in conjunction with a body onload event, the user experiences a denial-of-service attack or a system crash.

Prevention
Despite its relative severity, Microsoft has not yet issued a patch for this Internet Explorer flaw. As a workaround, security experts suggest disabling Active Scripting within Internet Explorer. ZDNet's George Ou explains the process in this How-to blog.