The US-CERT is urging Web surfers to immediately disable ActiveX controls from Internet Explorer to protect against a swath of publicly reported—and unpatched—software vulnerabilities.

The US-CERT (Computer Emergency Response Team) recommendation follows the release of exploit code for multiple zero-day flaws in image uploaders used by Facebook and MySpace and bugs in the ActiveX control that ships with the Yahoo Music Jukebox software.

The exploits, posted to the Milw0rm.com Web site, provides a roadmap for full remote code execution attacks on Windows computers.

ActiveX controls, commonly used in Windows Web applications for animation displays or to enhance UI functions to include items such as spreadsheets and toolbars, but the technology has been plagued by critical vulnerabilities and implementation issues.

According to Will Dormann, a security researcher who has been beating the ActiveX security drum repeatedly over the last few years, the use of ActiveX in a Web browser greatly increases the attack surface, or "attackability," of a system.

Because vulnerabilities ActiveX objects may be exploited via Internet Explorer, even if the object was never designed to be used in a Web browser, security researchers say it is a prime target for drive-by malware downloads.

Attacks Inevitable

According to Erik Kamerling, a vulnerability analyst at Symantec's DeepSight threat center, the availability of exploits for flaws in high-profile targets like Facebook and MySpace is cause for concern.
 
Although Symantec is unaware of in-the-wild exploitation of the ActiveX flaws, there's a feeling that attacks are inevitable.

"[We have] confirmed that these issues can be used to execute code or crash the vulnerable applications. Judging by the wide distribution of these controls, we assume that these issues will be used by attackers and we are monitoring for such developments," Kamerling said in a warning to DeepSight members.

In all, Kamerling said there are three new vulnerabilities in widely deployed ActiveX controls as well as one exploit for a related, recently disclosed issue.  

"Two of the issues affect the Aurigma and Facebook ImageUploader library. Although very similar to the recent Facebook, Myspace, and Aurigma image-upload issues disclosed on January 31, 2008, these new ImageUploader issues are distinct and affect different properties. The remaining two vulnerabilities affect Yahoo! Jukebox Mediagrid and DataGrid ActiveX controls," he added.

"In tandem with the public release of this information, remote code-execution exploits targeting the Aurigma, Facebook, and Yahoo! issues were released. Each issue allows remote attackers to execute arbitrary code in the context of the application using the ActiveX control (typically Internet Explorer)," Kamerling said.

In the absence of patches, Symantec recommends that IE users take "extreme caution" when browsing the Web and ensure that the browser is configured with the highest security settings.
 
The US-CERT goes a step further, recommending that IE users completely disable ActiveX scripting in the browser.