IE7 Security and Application Compatibility

One of Microsoft’s main goals with Internet Explorer 7 (IE7) was to improve Web browsing security. However, many of the security-related improvements to IE7 may degrade some Web sites and applications, and break others entirely.

What Might Break?

Developers of Web sites and applications should understand the following IE7 behaviors.

Extensions. On Windows Vista, IE7 will run in Protected Mode by default, meaning that it will run as a low-privileged application and will be able to write data only to IE-specific folders, such as Temporary Internet Files, History, Downloads, and Favorites. It will be unable to write to higher-privileged areas of the OS, such as the Registry or other files and folders. This has implications for IE extensions, which allow other applications to run from within IE. For example, developers will have to take special steps to enable extensions to save content (such as an Excel spreadsheet stored on a Web server) to permanent locations on the user’s hard drive.