Microsoft is investigating public reports of a vulnerability in Internet Explorer 6, Internet Explorer 7, Internet Explorer 8, and Internet Explorer 9. Internet Explorer 10 is not affected. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability. Applying the Microsoft Fix it solution, "Prevent Memory Corruption via ExecCommand in Internet Explorer," prevents the exploitation of this issue. See the Suggested Actions section of this advisory for more information.
A remote code execution vulnerability exists in the way that Internet Explorer accesses an object in memory that has been deleted or has not been properly allocated. The vulnerability may corrupt memory in a way that could allow an attacker to execute arbitrary code in the context of the current user within Internet Explorer. An attacker could host a specially crafted website that is designed to exploit this vulnerability through Internet Explorer and then convince a user to view the website.
On completion of this investigation, Microsoft will take the appropriate action to protect our customers, which may include providing a solution through our monthly security update release process, or an out-of-cycle security update, depending on customer needs.
We are actively working with partners in our Link Removed due to 404 Error (MAPP) to provide information that they can use to provide broader protections to customers. In addition, we are actively working with partners to monitor the threat landscape and take action against malicious sites that attempt to exploit this vulnerability.
Microsoft continues to encourage customers to follow the guidance in the Link Removed - Invalid URL of enabling a firewall, applying all software updates and installing anti-virus and anti-spyware software.