Administering Internet Explorer : Managing Windows Internet Explorer Settings (part 1) - Managing Cache

Because it's a built-in application, it's important to understand Internet Explorer settings and capabilities. Knowing how to manipulate these settings will help you support your enterprise Window 7 users. This section covers the following settings and capabilities:

• Managing cache

• InPrivate Browsing

• InPrivate Filtering

• SmartScreen Filter

• Security zones

• Protected Mode
  

1. Managing Cache

Windows Internet Explorer maintains different types of information for each web page you visit. Much of this stored data is used to make your next visit quicker. The data is stored in a location commonly called cache.

Data stored in cache includes

• List of web pages by URL

• Copies of web pages

• Cookies

• Images such as .jpeg and .gif

• Media files such as music or video files

• Style sheets including cascading style sheets (CSS) and Extensible Stylesheet Language (XSL) style sheets

• Script files

• Any data that is typed into forms if AutoComplete settings are enabled

• Any saved passwords that are automatically filled in when you sign on to a website

• Some installation applications that were downloaded for immediate installation

Forms data and passwords that are saved depend on how IE is configured. Figure 1 shows the settings page you can use to enable or disable the data entered into web page forms. You can access this page via Internet Options by clicking Tools => Internet Options from any open IE window.

Figure 1. IE AutoComplete settings

1.1. Viewing Cache Contents

You can view the files stored in cache. Similarly, if someone else has access to your system, they can view the files stored in cache.

The default cache location for IE is C:\Users\%username%\AppData\Local\Microsoft\Windows\Temporary Internet Files.

AppData is a hidden folder, so it probably won't show up unless you've already changed the settings. You can cause hidden files to appear in Windows Explorer by clicking Organize and then choosing Folder And Search Options, selecting the View tab, and picking Show Hidden Files, Folders, And Drives.

You will then be able to browse to C:\Users\%username%\AppData\Local\Microsoft\Windows.

However, the Temporary Internet Files folder is a system folder. You need to enable the display of protected operating system files before you'll see it. You can do this from the same View tab that allows you to enable viewing of hidden files and folders. Deselect Hide Protected Operating System Files (Recommended).

The display will look similar to Figure 2. The two arrows show the settings needed to display the contents of cache.

Figure 2. Configuring Windows Explorer settings to show hidden and system files

Cookies are simple text files that are written to your hard drive by many websites. Cookies are used to track user activity and provide targeted advertising. When you visit a website, cookies are written to the system. When you visit the website or related sites again, additional data is gathered on your activities. When you return to the website, the cookie is read, and it provides the website with information about you.

As an example, if you've ever purchased something online, a cookie was probably written to your system that could identify you when you return to that site. When you return, the cookie is read, and the website knows who you are.

Cookies are stored in the \Users\%username%\AppData\Roaming\Microsoft\Windows\Cookies folder.

History data includes all the sites a user has visited. It is stored in the \Users\%username%\AppData\Local\Microsoft\Windows\History folder. You can also click the Favorites button on the toolbar in the browser and select the History tab to view this data.

When a web page prompts a user to download a file, the file is stored in the Windows\Downloaded Program Files folder.

The Registry also holds some data related to IE usage. Although this requires you to dig a little deeper, you may need access to this information at some point. It's certainly important to realize how easy it is for an attacker to gain access to this information if they have unrestricted physical access to the computer. The three relevant IE keys are as follows:

IE Typed URLs

This key shows URLs that a user typed, as opposed to links that a user clicked. You can access this from the HKEY_Current_User\Software\Microsoft\Internet Explorer\TypedURLs node.

IE Forms AutoComplete

This key includes information stored by AutoComplete. Although the information isn't in clear text, there are tools available that can read the data. You can access this key from the HKEY_Current_User\Software\Microsoft\Internet Explorer\IntelliForms\Storage1 node.

IE Password AutoComplete

This key includes stored passwords used by AutoComplete. Although the information isn't in clear text, there are tools available that can read the data. You can access this key from the HKEY_Current_User\Software\Microsoft\Internet Explorer\IntelliForms\Storage2 node.

1.2. Clearing Cache

You can clear cache by manipulating the Internet Options page. Figure 3 shows the page you can use to delete browsing history. You can get to this page by clicking Tools => Internet Options, and clicking the Delete button in the Browsing History area.

Figure 3. Deleting browsing history

Notice that you can choose what data to delete. Exercise 1 shows you how to view the current contents of cache and then clear it.

Several Group Policy settings allow you to manipulate what a user can delete. Settings exist in both the User Configuration and Computer Configuration nodes. The settings are located in the Administrative Templates => Windows Components => Internet Explorer => Delete Browsing History node.

The following settings apply to at least IE version 8.0 in Windows 7:

• Prevent Deleting Cookies

• Prevent Deleting Web Sites That The User Has Visited

• Configure Delete Browsing History In Exit

• Prevent Deleting Temporary Internet Files

• Prevent Deleting Favorites Site Data

Some settings were introduced with Windows Vista and require at least IE version 7.0:

• Turn Off "Delete Browsing History" Functionality

• Prevent Deleting Form Data

• Prevent Deleting Passwords