Windows Vista Security: Praxisorientierte Sicherheit für Profis

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Chapter 11: Securing and Sharing Your Data

Securing Your Data

Disk drives and devices with removable storage are formatted with a filesystem. The

filesystem allows you to create and manage files. The format of the disk that you are

working with determines the file security options that are available. You can format

disks by using either File Allocation Table (FAT) or NT File System (NTFS). As dis-

cussed in the sections that follow, FAT and NTFS are a bit different in the way they

work.

FAT Versus NTFS

Both FAT and NTFS come in several different variations, and in some cases, the type

of device you are working with determines which variation is used. With FAT, the

number of bits used with the allocation table determines the variant you are working

with and the maximum volume size. You’ll find that USB flash devices and MP3

players with 4 GB or less of storage are formatted with the 16-bit version of FAT.

FAT16, also known simply as FAT, defines its file allocation tables using 16 bits.

FAT16 is used because it is the most efficient version of FAT for volume sizes of up

to 4 GB.

If you use devices with removable storage that have file sizes larger than 4 GB, such

as a removable hard disk, the device will in most cases use the 32-bit version of FAT,

known as FAT32. FAT32 defines its file allocation tables using 32 bits, which allows

you to have volumes larger than 32 GB. Devices with removable storage use FAT

because it has no security controls, allowing you to access your data on multiple

computers simply by connecting your device to those computers.

On the other hand, NTFS allows you to control access to files and folders by assign-

ing permissions. At home, your computer will typically have file access permissions

only for accounts configured on the local computer. At the office, your computer will

typically have file access permissions for accounts configured on the local computer

as well as accounts configured for your network. While NTFS supports just about

any volume size you’ll want to work with, you can’t necessarily move devices format-

ted with NTFS from one computer to another and gain access to all the data on these

devices. You may not be able to do this because NTFS access permissions are set

using accounts that are specific to a single computer, to a network, or to both.

File Attributes

All files and folders, whether on FAT- or NTFS-formatted disks, can be marked with

attributes that give you limited control over how a file or folder is used. The file

attributes you can use are:

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Read-only

Specifies that the file or folder is read-only and cannot be modified

Hidden

Specifies that the file or folder is hidden and can be viewed only if the folder

option “Show hidden files and folders” is enabled

System

Identifies a system file or folder that can be viewed only if the folder option

“Hide protected operating system files” is disabled

You can view or change the Read-Only and Hidden attributes on a file or folder by

completing the following steps:

1. In Windows Explorer, right-click the file or folder to display its Properties dia-

log box.

2. On the General tab, shown in Figure 11-1, select the Read-only checkbox to

make a file or folder read-only. Clear the Read-only checkbox to allow a file or

folder to be read and modified.

3. To hide a file or folder so that it can be viewed only if the folder option “Show

hidden files and folders” is enabled, select the Hidden checkbox. Otherwise,

clear this checkbox to allow a file or folder to be viewed normally.

4. Click OK to save your changes.

Figure 11-1. Viewing and setting file attributes

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Chapter 11: Securing and Sharing Your Data

Generally, Windows Vista manages the system attribute. Windows Vista marks files

and folders that you shouldn’t modify as being system files. You can view files and

folders marked with the hidden and system attributes by completing the following

steps:

1. In Windows Explorer, click Organize on the toolbar and then select Folder and

Search Options.

2. On the View tab, shown in Figure 11-2, select “Show hidden files and folders” to

show hidden files and folders.

3. To show system files and folders, clear the “Hide protected operating system

files” checkbox.

4. Click OK to save your settings.

Although these attributes can be set on files and folders, anyone with access to a disk

or device can override or change these settings. This means there are no safeguards

for file access or deletion that someone can’t override easily.

Figure 11-2. Showing hidden files and folders