A researcher over at the Internet Storm Center has created a powerful GUI that will set the kill-bits on vulnerable ActiveX controls used in Facebook, Myspace, and Yahoo apps. These popular apps came under attack on Monday after researchers Elazar Broad and Krystian Kloskowski disclosed their findings to a online security newsgroup.
On Tuesday, exploits for the Yahoo apps were reported circulating. There is currently no patch from the individual vendors, so the only workaround is to disable the several specific, vulnerable ActiveX controls. (ActiveX controls were developed by Microsoft for use with Internet Explorer and other browsers.)
The kill-bit tool first checks your system to see if any of the vulnerable CLSIDs exist. If so, the tool saves a copy of any values currently set, then updates the display to show that the CLSID--the unique sequence assigned to each ActiveX component that specifies which control you are using--exists. It also shows whether the kill-bit flag is set. To set the kill-bit, just check the box beside any of the affected ActiveX controls then click on the "Set" button. Unchecking any of the boxes will either reset the "Compatibility Flags" to their saved value or remove the CLSID entirely (if you didn't have the control installed in the first place).
SANS suggests setting the kill-bits for all of the affected ActiveX controls, and, even if you don't currently have one or more of these CLSIDs installed on your machine, go ahead set the kill-bit for controls that might be added to your system in the future.