It needs Microsoft Internet Explorer and MSDDS.DLL (a component installed by Visual Studio .net and other apps) present in order to work. As of right now (Thursday) there are no known malwares in the wild that are using the exploit. Yet.
You can find the dll located in Windows at "Program Files\Common Files\MicrosoftShared\MSDesigners7". It may also be installed by the applications .Net Framework 1.1 Microsoft Office (2000, 2002, XP), Microsoft Project Visio, Access 11 (2003) runtime, and the ATI Catalyst driver installed by newer ATI video cards. Interestingly, the version of MSDDS.DLL installed with Office 2003 is not vulnerable.
There are mitigations for the exploit. For instance, Using a registry editor, you can set "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\ActiveX Compatibility\EC444CB6-3E7E-4865-B1C3- 0DE72EF39B3F\Compatibility Flags=0x00000400" to set the kill bit for the component. Whether this will break mission critical apps requires testing, as usual.
You can also use something other than IE, but this may not be a valid option if your organization has settled on IE as default browser. Of course, revisiting that decision might be a good idea considering all the IE vulnerabilities of late.
A Microsoft spokesperson noted that "At this time, Microsoft is aggressively investigating these new public reports. We are not aware of attacks that try to use the reported vulnerability or of customer impact at this time. Upon completion of this investigation, Microsoft will take the appropriate action to help protect our customers. This may include providing a security update through our monthly release process or providing a security advisory." I guess that means that they will do what they want to do when they have to do it.
As the malware writers continually raise the stakes and the quickness of their releases, defenders have to be able to respond. This kind of problem isnt going away. It most likely will get worse in the future. This one should serve as a wake-up call to have policies in place (as well as the enterprise-wide tools) necessary to do dynamic reconfiguration as a situation demands. The problems of changing one machine are trivial, but they are massive for thousands of machines.
My esteemed colleague Steven J. Vaughn-Nichols opined yesterday that the latest problems with malware should make enterprises think about switching to Linux. Well, an unpatched Linux system (or Mac OS X for that matter) can have the same class of serious problems as a Windows network. It also may be that a sweeping OS change is just out of the question because of institutional inertia. It would just be too big of a job.
But what should not be too big of a job regardless of your OS is to have a process in place that allows for rapid changes as they are needed. The aphorism that "security isnt a product, its a process" has never been more true.
Larry Loeb was consulting editor for BYTE magazine and senior editor of WebWeek. He serves as a subject matter expert for the Department of Defenses Information Assurance Technology Analysis Center, and is on the American Dental Associations WG-1 and MD 156 electronic medical records working groups. Larrys latest book is "Hackproofing XML," published by Syngress (Rockland, Mass.). If youve got a tip for Larry, contact him at firstname.lastname@example.org.