Windows Vista : Protecting User Data - Protecting User Profiles

In Windows, user data is stored within the user profile along with any configuration information and data related to the user's preferences. Data includes user-generated documents, desktop preferences, Internet favorites, and so on. Application settings are also contained within the profile and include items such as custom dictionaries, custom toolbars, and anything else that pertains to the application itself and how it has been customized by the user. Other application-related data — data that pertains to every user of the system — is stored within special profiles that apply to all users.

Profile information is not only stored within the file system, but also is included in special sections of the Windows Registry under the HKey_Users hierarchy. When users are logged on, their profile information is copied from the HKey_Users hierarchy into the HKey_Current_User section of the Registry. It remains there until the user logs off at which point updates are copied back to HKey_Users. Some information is stored in memory only while the user is logged on. This information is contained within the NTUSER.DAT file, a core profile file, which requires special handling because it is always locked while in use.

The first thing you notice when you begin looking at profiles in Windows Vista is that they are completely different from previous versions. Information is stored in a different file structure than with any of the legacy versions of Windows. Because of this, Microsoft has introduced the concept of junction points, redirection points that appear as normal folders to applications and users. Junction points provide backwards compatibility for older applications that need to address the legacy folder structure used for profile storage. Finally, the profile folder structure itself has been completely modified to provide better support for features such as roaming profiles — profiles that are stored on network shares to make them accessible to users on any computer in your network.

Microsoft modified the profile structure in Vista to facilitate profile management, as shown in Figure 1. Because of this, several items have changed within the profile file structure:

• Profiles are stored under the C:\Users folder.

• Data assigned to every user is stored within the C:\Users\Public folder.

• Data used to generate a new profile is stored within the C:\Users\Default folder.

• Application data that is required for all users is stored within the C:\ProgramData folder.

• A new folder, C:\Users\username\AppData contains user-specific application data. Note that username is the user's account name in Windows.

• The AppData folder includes three subfolders:

  • Local includes data that does not move with the user when they change from computer to computer. Most often, data in this folder is too large to transfer from the local PC to a network share. For example, Outlook personal storage files (.PST) are located in this folder.

  • LocalLow includes data that is local but considered low priority.

  • Roaming includes data that can be copied to a network share for availability to roaming users. As shown in Figure 2, the Start Menu is located under this folder.

• Data folders include Contacts, Desktop, Documents, Downloads, Favorites, Links, Music, Pictures, Saved Games, Searches, and Videos. Some apply to business use while others are more focused on personal use.

When you plan to protect user data, you must carefully consider which of the folders in the user profile you will protect.

Figure 1. The Vista user profile structure

Figure 2. The contents of the Roaming folder in the Vista user profile