Windows Vista SecurityBy: Chris ReberApril 22, 2008

Agenda

Vista Security Overview User Account Control Authentication Firewall Enhancement Windows Service Hardening Data Protection

Vista Security Enhancements Windows Vista is hailed as the most

secure Windows version yet. Microsoft utilized a secure

developmental lifecycle to create the system.

They hardened the services and added enhancements for 64-bit computing.

There are new User, Network, and Application Security Options.

New Data Protection Options. Added security options in IE7.

User Account Controls

Allows users to be productive and change common settings while running as a standard user, without requiring administrative privileges.

Prevents users from making potentially dangerous changes to their computers, without limiting their ability to run applications.

Authentication

Includes new authentication architecture that is easier for third-party developers to extend.

This will lead to a wider choice of smart cards, fingerprint scanners, and other forms of strong authentication.

Firewall Enhancements

The new outbound filtering in the firewall provides administrative control over peer-to-peer sharing applications and other similar applications that businesses want to restrict.

Windows Service Hardening Limits the damage attackers can

do in the unlikely event that they are able to successfully compromise a service.

Increased to Six Service Accounts. The risk of attackers making

permanent changes to the Windows Vista client or attacking other computers on the network is reduced.

Data Protection

BitLocker Helps prevent unauthorized

access to data on lost or stolen computers by combining two major data-protection procedures. Encrypting the entire Windows

operating system volume on the hard disk.

Verifying the integrity of early boot components and boot configuration data.

BitLocker Requirements

Two NTFS-formatted volumes: A "boot volume" with a minimum

size of 1.5GB, where the OS boots from.

And the "system volume" which contains the operating system.

Trusted Platform Module (TPM v1.2).

Trusted Computing Group (TCG)-compliant BIOS for use with TPM.

BitLocker Modes Transparent Operation Mode User Authentication Mode USB Key Mode

Transparent Operation Mode This mode exploits the

capabilities of the TPM 1.2 hardware to provide for a transparent user experience.

The user logs onto Windows Vista as normal. The key used for the disk encryption

is sealed (encrypted) by the TPM chip and will only be released to the OS loader code if the early boot files appear to be unmodified.

User Authentication Mode This mode requires that the user

provide some authentication to the pre-boot environment in order to be able to boot the OS.

Two authentication modes are supported: a pre-boot PIN entered by the user or a USB key.

USB Key Mode

The user must insert a USB device that contains a startup key into the computer to be able to boot the protected OS.

Note that this mode requires that the BIOS on the protected machine supports the reading of USB devices in the pre-OS environment.

Combinations of Modes

The following combination of the modes are supported: TPM TPM + PIN TPM + PIN + USB Key TPM + USB Key USB Key

BitLocker Key Relationships

BitLocker Relationships

BitLocker Relationships

BitLocker Encryption

AES-CBC + Elephant Diffuser There are four separate

operations in each encryption. The plaintext is exclusive-orred (xorred) with a sector key, then run through two (unkeyed) diffusers, and finally encrypted with AES in CBC mode.

AES-CBC + diffuser

Sector Key Creation

Where E () is the AES encryption function, Ksec is the 128 or 256-bit key for this component.

e() is the encoding function used in the AES-CBC layer, and e‘ (s) is the same as e(s) except that the last byte of the result has the value 128.

The sector key Ks is repeated as many times as necessary to get a key the size of the block, and the result is xorred into the plaintext.

Diffuser A (Encryption)

The value i is a loop counter that goes around the data array Acycles = 5 times. (Remember that all indices are modulo n, so the wrap-around is automatic.) The addition is modulo 232, <<< is the rotate-left operator, and R(a) := [9; 0; 13; 0] is an array of 4 constants that specify the rotation amounts.

Diffuser B (Encryption)

Diffuser B is very similar to Diffuser A, however, the R (b) := [0; 10; 0; 25] and the Bcycles is only 3.

AES-CBC

The AES key KAES is either 128 bits or 256 bits, depending on the selected version. The block size is a always a multiple of 16 bytes, so no padding is necessary.

E () is the AES encryption function, and e() is an encoding function that maps each sector number s into a unique 16-byte value.

Note that IVs depends on the key and the sector number, but not on the data.

AES-CBC + diffuser

Current Limitations

Bitlocker only available on Windows Vista Ultimate, Enterprise and Server 2008.

Vista can only encrypt the system volume, further capability to be added with SP1.

Security Concerns

No Back Door for Law Enforcement When operating in “Transparent

Operation Mode” or “User Authentication Mode” the system is vulnerable to “Cold Boot Attacks”

When in "USB Key"-only mode a piece of software could read and record the key for later use to exploit the machine.

Agenda

Vista Security Overview User Account Control Authentication Firewall Enhancement Windows Service Hardening Data Protection Questions

Questions

References http://technet2.microsoft.com/WindowsVista/en/library/

ba1a3800-ce29-4f09-89ef-65bce923cdb51033.mspx?mfr=true

http://207.46.196.114/windowsserver2008/en/library/2d130e11-a796-43b7-98ed-d389cad285f51033.mspx?mfr=true

http://en.wikipedia.org/wiki/BitLocker_Drive_Encryption

“AES-CBC + Elephant diffuser A Disk Encryption Algorithm for Windows Vista”, Niels Ferguson, Microsoft, August 2006

“Security Enhancements in Windows Vista”, Microsoft Corp, May 2007. http://www.microsoft.com/presspass/newsroom/security/

VistaSecurity.mspx