The flaw focuses on IE's inline frames, often used for serving ads, which typically come from a different domain than content that appears on the same Web page.

Thomas Claburn, Editor at Large, Enterprise Mobility

June 30, 2008

2 Min Read

Microsoft's Internet Explorer 6, 7, and 8 beta 1 appear to contain a security flaw that could subject users who visit a malicious Web site or open a malicious e-mail message to arbitrary code.

U.S. CERT has published a vulnerability note indicating Internet Explorer doesn't handle document frames securely.

Document frames can be used to subdivide Web pages such that the content associated with each division comes from a different server or domain. These "iframes," or inline frames, often are used for serving ads, which typically come from a different domain than content that appears on the same Web page.

The problem, as U.S. CERT describes it, is that "Microsoft Internet Explorer fails to properly restrict access to a document's frames, which may allow an attacker to modify the contents of frames in a different domain."

IE includes restrictions that limit the information one frame can get from another, but it appears that certain events, such as the "onmousedown" event, are not associated with a specific domain and thus are not sufficiently restricted.

Secunia, a computer security firm, on Thursday published a security advisory warning that Internet Explorer 7.x is vulnerable to a frame location handling vulnerability. It said that other versions of IE may also be affected.

The U.S. CERT vulnerability note says that Internet Explorer 6, 7, and 8 beta 1 are vulnerable and that proof-of-concept code has been published.

The proof-of-concept code was first published in May at a Web site maintained by "sirdarckcat." It can be used to hijack an iframe window and capture keystrokes.

According to Bill Sisk, communications manager for Microsoft security response, Microsoft is investigating reports of a possible vulnerability in Internet Explorer. The company is unaware of any attacks trying to use the claimed vulnerability or of customer impact.

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2008

About the Author(s)

Thomas Claburn

Editor at Large, Enterprise Mobility

Thomas Claburn has been writing about business and technology since 1996, for publications such as New Architect, PC Computing, InformationWeek, Salon, Wired, and Ziff Davis Smart Business. Before that, he worked in film and television, having earned a not particularly useful master's degree in film production. He wrote the original treatment for 3DO's Killing Time, a short story that appeared in On Spec, and the screenplay for an independent film called The Hanged Man, which he would later direct. He's the author of a science fiction novel, Reflecting Fires, and a sadly neglected blog, Lot 49. His iPhone game, Blocfall, is available through the iTunes App Store. His wife is a talented jazz singer; he does not sing, which is for the best.

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