Serious Flaw in Internet Explorer Fixed

Microsoft Security Bulletin MS08-078 - Critical
Security Update for Internet Explorer (960714)
Published: December 17, 2008

Version: 1.0

Executive Summary
This security update resolves a publicly disclosed vulnerability. The vulnerability could allow remote code execution if a user views a specially crafted Web page using Internet Explorer. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.

This security update is rated Critical for Internet Explorer 5.01, Internet Explorer 6, Internet Explorer 6 Service Pack 1, and Internet Explorer 7. For information about Internet Explorer 8 Beta 2, please see the section, Frequently Asked Questions (FAQ) Related to This Security Update. For more information, see the subsection, Affected and Non-Affected Software, in this section.

The security update addresses the vulnerability by modifying the way Internet Explorer validates data binding parameters and handles the error resulting in the exploitable condition. For more information about the vulnerability, see the Frequently Asked Questions (FAQ) subsection under the next section, Vulnerability Information.

This security update also addresses the vulnerability first described in Microsoft Security Advisory 961051.

Recommendation. Microsoft recommends that customers apply the update immediately.

Known Issues. None

SAN FRANCISCO - Users of all current versions of Microsoft Corp.'s Internet Explorer browser might be vulnerable to having their computers hijacked because of a serious security hole in the software that had yet to be fixed Monday.

The flaw lets criminals commandeer victims' machines merely by tricking them into visiting Web sites tainted with malicious programming code. As many as 10,000 sites have been compromised since last week to exploit the browser flaw, according to antivirus software maker Trend Micro Inc.

The sites are mostly Chinese and have been serving up programs that steal passwords for computer games, which can be sold for money on the black market. However, the hole is such that it could be "adopted by more financially motivated criminals for more serious mayhem — that's a big fear right now," Paul Ferguson, a Trend Micro security researcher, said Monday.

"Zero-day" vulnerabilities like this are security holes that haven't been repaired by the software makers. They're a gold mine for criminals because users have few ways to fight off attacks.

The latest vulnerability is noteworthy because Internet Explorer is the default browser for most of the world's computers. Also, while Microsoft says it has detected attacks only against version 7 of Internet Explorer, which is the most widely used edition, the company warned that other versions are also potentially vulnerable.

Microsoft Security Advisory (961051)
Vulnerability in Internet Explorer Could Allow Remote Code Execution
Published: December 10, 2008 | Updated: December 13, 2008

Microsoft is continuing its investigation of public reports of attacks against a new vulnerability in Internet Explorer. Our investigation so far has shown that these attacks are only against Windows Internet Explorer 7 on supported editions of Windows XP Service Pack 2, Windows XP Service Pack 3, Windows Server 2003 Service Pack 1, Windows Server 2003 Service Pack 2, Windows Vista, Windows Vista Service Pack 1, and Windows Server 2008. Microsoft Internet Explorer 5.01 Service Pack 4, Microsoft Internet Explorer 6 Service Pack 1, Microsoft Internet Explorer 6, and Windows Internet Explorer 8 Beta 2 on all supported versions of Microsoft Windows are potentially vulnerable.