Use 'Protected Mode' To Secure IE 7, Microsoft Says

A setting in Internet Explorer 7 running on Windows Vista can help stave off a particular remote code execution attack, according to Microsoft's security team.

The setting, called "protected mode IE," runs IE 7 with lower privileges. It thwarts a vulnerability outlined in Microsoft's MS09-019 security bulletin, which was issued this week as part of Redmond's June security patch. Microsoft's security team outlined what IT pros should check in a blog post on Tuesday.

To avoid potential attacks, IE privileges at the highest level should be restricted in the browser. Such browser security is only enabled with the user account control (UAC) setting turned on. If either UAC or protected mode IE is turned off, the system could be vulnerable, the security team explained.

Right now, protected mode IE only applies to IE 7 on Windows Vista. However, it likely will be a continued as a feature in IE 8 for Windows 7, according to Microsoft's security team.

Even with protected mode IE, Microsoft recommends applying the MS09-19 patch. IE is the most used Web browser, so it's important to patch, security experts say.

"One of the high-profile bugs fixed in this recent patch release was discovered at the CanSecWest PWN2OWN competition," explained Andrew Storms, director of security at nCircle. "Client-side, browser-based vulnerabilities continue to top the charts for threats. So every user should put this patch at the top of their 'install immediately' list."

The bug described at CanSecWest reportedly made short work of Microsoft's data execution prevention function in IE 8, as well as its address space layout randomization technology.

Don Leatham, senior director of solutions and strategy at Lumension, intimates that there are larger issues at stake to ensure secure Web surfing.

"In the recent [patch] release, [there were] seven separate vulnerabilities across Internet Explorer 6 and 7 for both XP and Vista. And this means that almost all Windows users will soon be vulnerable while browsing the Web," Leatham said.

What's being patched is "the DHTML and HTML object handling capabilities of Internet Explorer, the core technologies in almost every Web page -- and that's big," Leatham added.

Microsoft provides more information about protected mode IE here.

On top of that, Microsoft's security team also described a "network protocol lockdown" configuration for IE that can be used as a workaround to restrict HTML content sent via certain protocols.

About the Author

Jabulani Leffall is an award-winning journalist whose work has appeared in the Financial Times of London, Investor's Business Daily, The Economist and CFO Magazine, among others.

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