Software Engineering Institute

Microsoft Windows XP provides the Macromedia Flash ActiveX control. Depending on the patch level of the system, it may be provided by either flash.ocx or flash6.ocx. This ActiveX control contains a use-after-free vulnerability, which can result in heap memory corruption. Note that this vulnerability does not affect systems that have Flash 9 or later installed, as newer versions of the Flash installer will replace the Macromedia Flash control that is provided by Windows.

By convincing a user to view a specially crafted HTML document (e.g., a web page or an HTML email message or attachment), an attacker may be able to execute arbitrary code.

We are unaware of a practical solution to this problem. Please see Microsoft Security Advisory (979267) for some workarounds, including:

Disable the Flash ActiveX control in Internet Explorer

The Flash ActiveX control can be disabled in Internet Explorer by setting the kill bit for the following CLSID:

{D27CDB6E-AE6D-11cf-96B8-444553540000}
More information about how to set the kill bit is available in Microsoft Support Document 240797. Alternatively, the following text can be saved as a .REG file and imported to set the kill bit for this control:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\{D27CDB6E-AE6D-11cf-96B8-444553540000}]
"Compatibility Flags"=dword:00000400
[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Internet Explorer\ActiveX Compatibility\{D27CDB6E-AE6D-11cf-96B8-444553540000}]
"Compatibility Flags"=dword:00000400
Remove Flash

Adobe has provided instructions for removing the Flash 6 ActiveX control. Alternatively, a utility has been provided to automatically remove the Flash ActiveX control and plug-in.

Apply an update

This issue can be mitigated by installing the latest version of Adobe Flash. Flash 6 is no longer supported, and installing Adobe Flash 10 will replace the existing Flash ActiveX control(s).

Disable ActiveX

Disabling ActiveX controls in the Internet Zone (or any zone used by an attacker) appears to prevent exploitation of this and other ActiveX vulnerabilities. Instructions for disabling ActiveX in the Internet Zone can be found in the "Securing Your Web Browser" document.