Microsoft Security Alert: Vulnerability in Internet Explorer Could Allow Remote Code Execution

Microsoft is continuing its investigation of public reports of attacks against a new vulnerability in Internet Explorer.

Here is what Microsoft has to say:

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.

The vulnerability exists as an invalid pointer reference in the data binding function of Internet Explorer. When data binding is enabled (which is the default state), it is possible under certain conditions for an object to be released without updating the array length, leaving the potential to access the deleted object's memory space. This can cause Internet Explorer to exit unexpectedly, in a state that is exploitable.

At this time, we are aware only of limited attacks that attempt to use this vulnerability against Windows Internet Explorer 7. Our investigation of these attacks so far has verified that they are not successful against customers who have applied the workarounds listed in this advisory. Additionally, there are mitigations that increase the difficulty of exploiting this vulnerability.

We are actively working with partners in our Microsoft Active Protections Program (MAPP) and our Microsoft Security Response Alliance (MSRA) programs to provide information that they can use to provide broader protections to customers. In addition, we’re actively working with partners to monitor the threat landscape and take action against malicious sites that attempt to exploit this vulnerability.

We are actively investigating the vulnerability these attacks attempt to exploit. We will continue to monitor the threat environment and update this advisory if this situation changes. On completion of this investigation, Microsoft will take the appropriate action to protect our customers, which may include providing a solution through a service pack, our monthly security update release process, or an out-of-cycle security update, depending on customer needs.

Microsoft continues to encourage customers to follow the "Protect Your Computer" guidance of enabling a firewall, applying all software updates and installing anti-virus and anti-spyware software. Additional information can be found at Security at home.

Mitigating Factors:

• Protected Mode in Internet Explorer 7 and Internet Explorer 8 in Windows Vista limits the impact of the vulnerability.

• By default, Internet Explorer on Windows Server 2003 and Windows Server 2008 runs in a restricted mode that is known as Enhanced Security Configuration. This mode sets the security level for the Internet zone to High. This is a mitigating factor for Web sites that you have not added to the Internet Explorer Trusted sites zone.

•An attacker who successfully exploited this vulnerability could gain the same user rights as the local user. Users whose accounts are configured to have fewer user rights on the system could be less affected than users who operate with administrative user rights.

•Currently known attacks cannot exploit this issue automatically through e-mail.

Click Here For The Advisory Statement.