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Security pros: Kill ActiveX

Wave of IE plug-in bugs prompts US-CERT to recommend disabling ActiveX

February 5, 2008 12:00 PM ET

Computerworld - A wave of bugs in the plug-in technology used by Microsoft Corp.'s Internet Explorer browser has some security experts, including those at US-CERT, recommending that users disable all ActiveX controls.

The U. S. Computer Emergency Readiness Team, part of the U.S. Department of Homeland Security, put it bluntly in advisories posted in the last two days: "US-CERT encourages users to disable ActiveX controls as described in the Securing Your Web Browser document," the organization recommended.

US-CERT's advice was prompted by multiple vulnerabilities in high-profile ActiveX components used by members of Facebook and MySpace and by users of Yahoo Inc.'s music services.

Three new vulnerabilities in the photo uploader software used by both Facebook and MySpace were disclosed yesterday by researcher Elezar Broad, who on Monday also posted sample attack code for a pair of critical bugs in Yahoo's Music Jukebox. Last week, Broad had pinned the Facebook and MySpace ActiveX controls with two other flaws. All five of the Facebook/MySpace vulnerabilities originated with an ActiveX control developed by Aurigma Inc.

As the number of vulnerabilities mounted, security professionals began ringing the alarm. On Monday, for instance, Symantec analysts urged users to "use caution when browsing the Web" and told IT administrators to disable the relevant ActiveX controls by setting several "kill bits" in the Windows registry.

US-CERT, however, offered up more aggressive advice as it recommended users move IE's security level to the "High" setting, which completely disables all ActiveX controls.

Setting IE's security level to 'High' disables all ActiveX controls. To get here, select Internet Options from the Tools menu, then click on the Security tab. Click Internet at the top for the zone, then move the slider up to the maximum.

"That's the easiest way to protect yourself," agreed Oliver Friedrichs, director of Symantec Corp.'s security response group. "But it can also have an adverse impact on your browsing experience." A compromise, said Friedrichs, would be to disable "only those plug-ins that pose a current and imminent threat," such as the flawed ActiveX controls used by Facebook, MySpace and Yahoo.

Disabling individual ActiveX controls, however, requires editing the Windows registry. That's too scary for most home users to contemplate, but business users are another matter. "That approach is hard to argue against in the enterprise," said Friedrichs, who noted that there are tools available that let corporate IT administrators push registry changes -- including new keys that disable specific ActiveX controls -- to all users.

The SANS Institute's Internet Storm Center acknowledged that setting kill bits is beyond the ken of most users; one of its researchers came up with a graphical interface-based tool that sets and clears the kill bits of six ActiveX controls that have been tagged with bugs in the past week. The free tool can be downloaded at the ISC's Web site.



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