Microsoft Windows Security Resource Kit

Security Settings in Internet Explorer 6

The Web browser has become a mission-critical application for nearly all organizations. Unfortunately, browsing Web sites on the Internet also can be a major security risk because Web browsers provide attackers with direct access to an organization s local area network (LAN). Fortunately, Internet Explorer enables administrators to easily configure privacy and security settings, and enables knowledgeable users to view privacy and security information to make decisions on whether to trust specific Web sites.

Privacy Settings

In April 2002, the World Wide Web Consortium (W3C) found at http://www.w3c.org ratified the Platform for Privacy Preferences Project (P3P), an industry standard providing a simple, automated way for users to gain more control over the use of their personal information on Web sites they visit. Internet Explorer 6 fully supports P3P version 1.0. P3P helps protect the privacy of users personal information on the Internet by making it easier for users to decide whether and under which circumstances personal information is disclosed to Web sites.

In Internet Explorer 6, users can define their privacy preferences for disclosing personal information. When users browse Web sites, Internet Explorer determines whether those sites abide by the P3P privacy standards. If the Web site does support P3P standards, Internet Explorer compares the user s privacy preferences to the Web site s privacy policy information. To be P3P compliant, a Web site must provide a clear definition of its privacy policies, including these:

Internet Explorer 6 includes a new Privacy Report option on its View menu. This option enables users to view P3P privacy information known as a privacy report on P3P-compliant Web sites. For example, to view the privacy report for the Microsoft Web site, follow these steps:

  1. Open Internet Explorer.

  2. In the Address box, type http://www.microsoft.com.

  3. Click View, and then click Privacy Report.

  4. From the Web Sites With Content On The Current Page box, select http://www.microsoft.com and then click Summary.

Figure 10-1 shows the privacy report for the Microsoft Web site.

Figure 10-1. P3P privacy report for Microsoft.com

In addition to viewing P3P-compliant Web site privacy reports, Internet Explorer 6 enables P3P support for user cookie management. A cookie is a small file that an individual Web site stores on your computer. Web sites can use cookies to maintain information and settings, such as your customization preferences. Two types of cookies exist: persistent cookies and session cookies. Persistent cookies include an expiration date that identifies when the browser can delete them. Session cookies do not have an expiration date; they are deleted when the user closes the browser.

Internet Explorer 6 includes advanced cookie management capabilities that determine whether cookies can be stored on a user s computer. When you configure your privacy preferences, you can configure Internet Explorer to handle cookies in the following ways:

An additional option enables you to always allow session cookies. Figure 10-2 shows the Advanced Privacy Settings user interface on which you can configure cookie management in Internet Explorer 6.

Figure 10-2. Advanced Privacy Settings user interface in Internet Explorer 6

For convenience, Internet Explorer 6 offers six predefined privacy configurations and an option to create a custom configuration. By default, Internet Explorer 6 is set to Medium for sites in the Internet zone. (We will discuss the Internet zone later in this chapter.) In addition to the predefined configurations, you can override the settings for individual Web sites on the Privacy tab of the Internet Options menu item (from the Tools menu). These are the predefined privacy configurations:

Security Zones

On most networks, the Web browser on a user s computer is an open communication channel from the Internet directly to the computer and the local network the computer is attached to. A malicious attacker can embed scripts in a Web site that, when viewed, attack the computer or the local network of the user browsing that Web site. To prevent attacks delivered through Web sites, you can use Internet Explorer security settings, which are configured by using security zones. Security zones in Internet Explorer are flexible and customizable, enabling you to configure browser security while maintaining Web site functionality.

Security zones group Web sites into categories based on levels of trust. When using Internet Explorer to browse Web sites, the security zone of the Web is displayed in the lower right-hand corner of the Internet Explorer System bar, as shown in Figure 10-3.

Figure 10-3. Viewing the current security zone in Internet Explorer

You can use four predefined levels of security with these security zones:

Table 10-1 shows the security configuration of the predefined security zones in Internet Explorer 6. We will discuss these security options in more detail momentarily. In addition to the predefined security levels, as mentioned earlier, you can create a custom level of security and assign it to a security zone.

Table 10-1. Default Security Zones in Internet Explorer 6

Security Option

Low

Medium-Low

Medium

High

Download Signed ActiveX Controls

Enable

Prompt

Prompt

Disable

Download Unsigned ActiveX Controls

Prompt

Disable

Disable

Disable

Initialize And Script ActiveX Controls Not Marked As Safe

Prompt

Disable

Disable

Disable

Run ActiveX Controls And Plug-Ins

Enable

Enable

Enable

Disable

Script ActiveX Controls Marked Safe For Scripting

Enable

Enable

Enable

Disable

File Download

Enable

Enable

Enable

Disable

Font Download

Enable

Enable

Enable

Prompt

Microsoft VM Java Permissions

Low safety

Medium safety

High safety

Disable Java

Access Data Sources Across Domains

Enable

Prompt

Disable

Disable

Allow META REFRESH

Enable

Enable

Enable

Disable

Display Mixed Content

Prompt

Prompt

Prompt

Prompt

Don t Prompt For Client Certificate Selection When No Certificates Or Only One Certificate Exists

Enable

Enable

Disable

Disable

Drag And Drop Or Copy And Paste Files

Enable

Enable

Enable

Prompt

Installation Of Desktop Items

Enable

Prompt

Prompt

Disable

Launching Programs And Files In An IFRAME

Enable

Prompt

Prompt

Disable

Navigate Subframes Across Different Domains

Enable

Enable

Enable

Disable

Software Channel Permissions

Low safety

Medium safety

Medium safety

High safety

Submit Nonencrypted Form Data

Enable

Enable

Prompt

Prompt

Userdata Persistence

Enable

Enable

Enable

Disable

Active Scripting

Enable

Enable

Enable

Disable

Allow Paste Operations Via Script

Enable

Enable

Enable

Disable

Scripting Of Java Applets

Enable

Enable

Enable

Disable

User Authentication

Automatic logon only in Intranet zone

Automatic logon only in Intranet zone

Automatic logon with current user name and password

Prompt for user name and password

When configuring security zones, you must remember that although security zones are configured and maintained in Internet Explorer, they also apply to other applications, such as Office XP; Microsoft Outlook Express and Microsoft Outlook Preview Pane and HTML messages; and HTML Help applications. These are the default security zones in Internet Explorer:

The security settings in Internet Explorer are divided into the following categories:

Unfortunately, no one correct implementation of these settings exists for all users or all organizations. You must analyze the business and technical requirements of your organization to configure these security settings in Internet Explorer.

ActiveX Controls and Plug-Ins

ActiveX controls enable Web sites to deliver interactive context to users through Internet Explorer. The ActiveX controls and plug-ins section of Internet Explorer 6 security includes settings for how Internet Explorer approves, downloads, runs, and scripts ActiveX controls. If a user downloads an ActiveX control that is hosted on a Web site that belongs to a different security zone from the page on which it is used, Internet Explorer applies the more restrictive of the two sites security zone settings. These are the ActiveX security settings:

Download Options

The Download options specify how Internet Explorer downloads files and fonts. These are the two options:

Microsoft VM Options

The Microsoft virtual machine (VM) options enable you to configure security for Microsoft VM, which is compatible with Java applets and libraries. In Windows XP, this section is available only after you download and install the Java Virtual Machine. Unless you have Java applications that users access through Internet Explorer, you should set the Java security to the Disable Java option. You can set the Microsoft VM security level to one of the following options:

Miscellaneous Options

The Miscellaneous options control whether users can access data sources across domains, submit data by using nonencrypted forms, launch applications and files from IFRAME elements, install desktop items, drag and drop files, copy and paste files, and access software channel features from this zone. These are the options:

Scripting Options

The Scripting options specify how Internet Explorer handles scripts embedded in Web pages:

The User Authentication Option

Only one User Authentication option exists: the Logon option. This option controls how HTTP user authentication is handled. Logon has the following settings:

In addition to the security settings in security zones, some global security settings apply to all security zones when using Internet Explorer. You can configure these global options on the Advanced tab of Internet Options. Here are the security settings on the Advanced tab and their default values:

Configuring Privacy and Security Settings in Internet Explorer 6

You can configure privacy and security settings in Internet Explorer manually though Internet Options from the Tools menu, during installation with the Internet Explorer Administration Kit (IEAK), or by using Group Policy. If you plan to deploy Internet Explorer in your organization, you should consider using the IEAK.

The IEAK is beyond the scope of this book, but you can get more information about it from the IEAK Web site at http://www.microsoft.com/windows/ieak/default.asp.

You can use Group Policy to manage the privacy and security settings in Internet Explorer on a per-user basis and control whether users can change settings on a per-user basis or a per-computer basis.

Group Policy in Windows 2000 enables you to centrally configure and manage Internet Explorer security on a per-user basis. To configure Internet Explorer privacy and security settings through Group Policy, open the Microsoft Management Console (MMC) on a computer running Windows XP and add the Group Policy snap-in. If you create a Group Policy object (GPO) on Windows 2000, you might not be able to configure the privacy settings unless you have Internet Explorer 6.0 or later installed.

After importing the security zones and privacy settings from the computer you are editing the GPO on, you can modify the settings and apply the GPO to a site, domain, or OU containing the user accounts that should be subject to the privacy and security settings. You can also export the settings into .ins and .cab files for use with the IEAK.

In addition to configuring the privacy and security zone settings, as a network administrator, you can configure whether the user can modify Internet Explorer security settings. You can configure the following settings in the user-related portion of Group Policy by selecting the Administrative Templates menu option, then Windows Components, and then Internet Explorer:

You also can make four Group Policy settings in the computer-related Internet Explorer security options. These settings will apply to all users of the computer.

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