Software Engineering Institute

Microsoft Internet Explorer contains an invalid pointer vulnerability in its data binding code. The vulnerability can be triggered when Internet Explorer or a program that uses Internet Explorer's components renders a document that contains more than one reference to the same data source. This flaw can cause an invalid array size and result in the accessing of memory space of a deleted object. Specially crafted content that performs data binding, such as an XML or HTML document, can cause IE to crash in a way that is exploitable. Limited testing has shown this vulnerability to affect Internet Explorer 6 and later, up to and including Internet Explorer 8 Beta 2. However, all versions of Internet Explorer from 4.0 and on may be at risk. We have confirmed that Outlook Express is also at risk. Exploit code for this vulnerability is publicly available.

By convincing a user to view a specially crafted document that performs data binding (e.g., a web page or email message or attachment), an attacker may be able to execute arbitrary code with the privileges of the user.

Apply an update

This issue is addressed in Microsoft Security Bulletin MS08-078. This update provides new versions of mshtml.dll and wmshtml.dll, depending on the target operating system. More details are available in Microsoft Knowledge Base Article 960714. Consider the following workarounds if you are unable to apply the update:

Disable the Microsoft OLE DB Row Position Library COM object

The most effective way of mitigating this vulnerability appears to be to disable the Microsoft OLE DB Row Position Library COM object. As outlined in the Microsoft Security Advisory, delete the following registry key:
Windows Registry Editor Version 5.00

[HKEY_CLASSES_ROOT\CLSID\{2048EEE6-7FA2-11D0-9E6A-00A0C9138C29}]
Note that once this change is made, all ADO (ActiveX Data Objects) applications that use the RowPosition property and related information and all OLE DB applications that use the OLE DB Row Position Library will not function properly.

Disable Active Scripting

This vulnerability can be mitigated by disabling Active Scripting in the Internet Zone, as specified in the "Securing Your Web Browser" document. Note that this will not block the vulnerability. IE still may crash when parsing specially crafted XML content. Disabling Active Scripting will mitigate a common method used to achieve code execution with this vulnerability.

Enable DEP in Internet Explorer 7

Enabling DEP in Internet Explorer 7 on Windows Vista can help mitigate this vulnerability by making it more difficult to achieve code execution using this vulnerability.