IE scripting flaw uncovered

Full disclosure

Security researchers yesterday released details of a cross domain scripting flaw in Internet Explorer ahead of a fix by Microsoft.

The flaw leaves applications that use WebBrowser control, including Microsoft IE, Outlook and Outlook Express (when run outside restricted zones), vulnerable to a variety of attacks, researchers from security consultancy PivX say.

Possible exploits include elevating privileges, arbitrary command execution, local file reading and stealing arbitrary cookies.

The vulnerability arises because the object property of embedded WebBrowser controls, which is used to embed external objects inside a page, is not subject to the cross domain security checks which embedded HTML documents ordinarily go through. It is explained in greater detail here

The upshot is that it's possible for crackers to construct exploits which escape any sandboxing and security zone restrictions. Such objects can be the WebBrowser control and other ActiveX controls, images or applets.

PivX have put together a series of proof of concept exploits to back up their warning. The vulnerability was notified to Microsoft on June 25 but Redmond has yet to develop a fix

To guard against the vulnerability, PivX suggests that administrators should disable ActiveX scripting until a patch is available.

The release of information about vulnerabilities has been a point of contention between independent security vendors and vendors, most notably Microsoft, recently. Research by the Hurwitz Group, released late last month, suggests users would like to see information disclosed full disclosure of security information.

PivX said it had decided to release information on this vulnerability following our report on this research.

According to PivX, Internet Explorer is subject to 19 unpatched security holes. ®

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