Microsoft Tightens IE 7's Security

Microsoft has detailed several changes in the way its upcoming Internet Explorer (IE) 7 browser will classify Web sites for security, aiming to reduce the likelihood that users will fall victim to malicious code.

The browser, which will be released separately and also as part of the forthcoming Windows Vista operating system, is expected to ship in 2006, probably before Vista.

More Specific Security

The current version, IE 6, has four classifications for Web sites: Internet, local intranet, trusted, and restricted. These enable users to apply different security rules for how the browser interacts with groups of Web sites. The browser uses the settings to determine, for example, if it will run Active X controls without first alerting the user.

The company has been working on improvements to prevent the browser from running malicious code in less restrictive security zones, wrote Microsoft engineers Vishu Gupta, Rob Franco, and Venkat Kudulur in Microsoft's IE Web log.

The local intranet zone is not really relevant for home users, the engineers said. Instead, a change has been made to IE 7 so that, when a PC is not on a managed corporate network, IE will treat apparent intranet sites as if they were on the Internet.

"This change effectively removes the attack surface of the intranet zone for home PC users." they wrote. They credit the change to an idea from a summer interrn working at the company.

Network Admin Options

However, if a machine is running on a domain, IE 7 will automatically detect the intranet sites and revert to the intranet zone settings. Network administrators will be able to set group policies to ensure the browser runs as desired, the engineers wrote.

In Microsoft Windows Vista, the Internet zone will run in what the company calls "protected mode," to help protect against attacks that IE has been victim to in the past. Another feature, ActiveX Opt-In, will reduce potential damage from malicious Active X controls in the Internet zone, the engineers said. Those changes will be reflected in a new security level setting for the Internet zone, "medium high."

The "Trusted sites" zone, which provides a lot of autonomy for specific Web sites selected by the end user, will also change. It will now have a default security setting of "medium," the same as the Internet zone in IE 6. Users will be able to lower the setting if they want to, the engineers wrote.