Microsoft released advisory KB972890 yesterday for a zero-day vulnerability found by ISS, warning of an attack on an ActiveX control for Microsoft Video. The main attack vector is for the user to browse a website that has the exploit installed with Internet Explorer- further interaction is not necessary, the attack is of the type called "drive-by". This makes the attack very dangerous as there is very little that Internet Explorer users can do to defend themselves. Security news here and here report that thousands of websites have started serving the exploits already, which is supported by the in-depth information that we are getting from our iDefense feed which has a long list of sites that are serving the exploits.
The described work arounds involve disabling 40+ classids in the registry, which should be scriptable by IT administrators. The Microsoft support website has a FixIt link which individual users can use to apply those changes to the registry.
QualysGuard detects this zero-day vulnerability as QID 90510, but does not raise it if you have the described workaround applied. We will be enhancing the detection as more information about workarounds and patches becomes available.
How do you deal with ActiveX controls, do you disable them in your default builds ? Let me know by sending feedback. We also will discuss this issue on our upcoming panel at the Black Hat security conference in Las Vegas with the present industry experts.