Security and safety features new to Windows Vista Part1

There are a number of security and safety features new to Windows Vista, most of which are not available in any prior Microsoft Windows operating system release.

Beginning in early 2002 with Microsoft's announcement of their Trustworthy Computing initiative, a great deal of work has gone into making Windows Vista a more secure operating system than its predecessors. Internally, Microsoft adopted a "Security Development Lifecycle"[1] with the underlying ethos of, "Secure by design, secure by default, secure in deployment". New code for Windows Vista was developed with the SDL methodology, and all existing code was reviewed and refactored to improve security.

Some specific areas where Windows Vista introduces new security and safety mechanisms include User Account Control, parental controls, Network Access Protection, a built-in anti-malware tool, and new digital content protection mechanisms.

User Account Control

User Account Control is a new infrastructure that requires user consent before allowing any action that requires administrative privileges. With this feature, all users, including users with administrative privileges, run in a standard user mode by default, since most applications do not require higher privileges. When some action is attempted that needs administrative privileges, such as installing new software or changing system settings, Windows will prompt the user whether to allow the action or not. If the user chooses to allow, the process initiating the action is elevated to a higher privilege context to continue. While standard users need to enter a username and password of an administrative account to get a process elevated (Over-the-shoulder Credentials), an administrator can choose to be prompted just for consent or ask for credentials.

UAC asks for credentials in a Secure Desktop mode, where the entire screen is faded out and temporarily disabled, to present only the elevation UI. This is to prevent spoofing of the UI or the mouse by the application requesting elevation. If the application requesting elevation does not have focus before the switch to Secure Desktop occurs, then its taskbar icon blinks, and when focussed, the elevation UI is presented (however, it is not possible to prevent a malicious application from silently obtaining the focus).

Since the Secure Desktop allows only highest privilege System applications to run, no user mode application can present its dialog boxes on that desktop, so any prompt for elevation consent can be safely assumed to be genuine. Additionally, this can also help protect against shatter attacks, which intercept Windows inter-process messages to run malicious code or spoof the user interface, by preventing unauthorized processes from sending messages to high privilege processes. Any process that wants to send a message to a high privilege process must get itself elevated to the higher privilege context, via UAC.

Applications written with the assumption that the user will be running with administrator privileges experienced problems in earlier versions of Windows when run from limited user accounts, often because they attempted to write to machine-wide or system directories (such as Program Files) or registry keys (notably HKLM)[2] UAC attempts to alleviate this using File and Registry Virtualization, which redirects writes (and subsequent reads) to a per-user location within the user’s profile. For example, if an application attempts to write to “C:\program files\appname\settings.ini” and the user doesn’t have permissions to write to that directory, the write will get redirected to “C:\Users\username\AppData\Local\VirtualStore\Program Files\appname\.”

Bitlocker Drive Encryption

Formerly known as "Secure Startup", this feature offers full disk encryption for the system volume. Using the command-line utility, it is possible to encrypt additional volumes. Bitlocker utilizes a USB key or Trusted Platform Module (compliant with the version 1.2 of the TCG specifications) to store its encryption key. It ensures that the computer running Windows Vista starts in a known-good state, and it also protects data from unauthorized access.[3] Data on the volume is encrypted with a Full Volume Encryption Key (FVEK), which is further encrypted with a Volume Master Key (VMK) and stored on the disk itself.

Windows Firewall

Windows Vista significantly improves the firewall[4] to address a number of concerns around the flexibility of Windows Firewall in a corporate environment:

* IPv6 connection filtering
* Outbound packet filtering, reflecting increasing concerns about spyware and viruses that attempt to "phone home".
* With the advanced packet filter, rules can also be specified for source and destination IP addresses and port ranges.
* Rules can be configured for services by its service name chosen by a list, without needing to specify the full path file name.
* IPsec is fully integrated, allowing connections to be allowed or denied based on security certificates, Kerberos authentication, etc. Encryption can also be required for any kind of connection. A connection security rule can be created using a wizard that handles the complex configuration of IPsec policies on the machine. Windows Firewall can allow traffic based on whether the traffic is secured by IPsec.
* A new management console snap-in named Windows Firewall with Advanced Security which provides access to many advanced options, including IPsec configuration, and enables remote administration.
* Ability to have separate firewall profiles for when computers are domain-joined or connected to a private or public network. Support for the creation of rules for enforcing server and domain isolation policies.

Windows Defender

Windows Vista includes Windows Defender, Microsoft's anti-spyware utility. According to Microsoft, it was renamed from 'Microsoft AntiSpyware' because it not only features scanning of the system for spyware, similar to other free products on the market, but also includes Real Time Security agents that monitor several common areas of Windows for changes which may be caused by spyware. These areas include Internet Explorer configuration and downloads, auto-start applications, system configuration settings, and add-ons to Windows such as Windows Shell extensions.

Windows Defender also includes the ability to easily remove ActiveX applications that are installed. It also incorporates the SpyNet network, which allows users to communicate with Microsoft, send what they consider is spyware, and check what applications are acceptable.

Windows Parental controls

Windows Vista includes a range of parental controls for non-domain user accounts. Windows Parental Controls rely on UAC to implement reduced rights account identities needed for offline restrictions. An administrator can apply parental control restrictions to other users on the computer. Facilities include:

* Web content blocking, including the ability to limit web browsing to "kids websites", as well as blocking particular categories of content such as "Pornography", "Drugs", "Web e-mail", "Web chat", and so on. File downloads may also be disabled. Web content filtering is implemented as a Winsock LSP filter.
* Time limitations on when the account may be used. When active, users are blocked from logging on if not already logged on. If they are logged on and the time limit is reached, user accounts are locked using Fast User Switching without the users being logged out to prevent unsaved data in that account from getting lost.
* Restrictions on what kind of games may be played. An administrator may choose from one of five different game rating services: ESRB (United States and Canada), PEGI (Europe), USK (Germany), OFLC (Australia and New Zealand), CERO (Japan). Ratings are used to determine the highest allowed game rating. As with web content blocking, a number of categories of content may also be blocked regardless of game ratings.
* Restrictions on what programs may be executed. Implemented using Windows Software Restriction Policies.
* Activity reports to monitor and log what was done under Parental Controls through event logging interfaces
* APIs expose the policy and in-box restrictions settings, and logging functionality for parental controls functionality to be extended or replaced.

Encrypting File System

Encrypting File System (EFS) in Windows Vista can also be used to encrypt the system page file and the per-user Offline Files cache. EFS is also more tightly integrated with enterprise Public Key Infrastructure (PKI), and supports using PKI-based key recovery, data recovery through EFS recovery certificates, or a combination of the two. There are also new Group Policies to require smart cards for EFS, enforce page file encryption, stipulate minimum key lengths for EFS, enforce encryption of the user’s Documents folder, and prohibit self-signed certificates. The EFS encryption key cache can be cleared when a user locks his workstation or after a certain time limit.

The Encrypting File System rekeying wizard allows the user to choose a certificate for EFS and to select and migrate existing files that will use the newly chosen certificate. Certificate Manager also allows users to export their EFS recovery certificates and private keys. Users are reminded to backup their EFS keys upon first use through a balloon notification. The rekeying wizard can also be used to migrate users in existing installations from software certificates to smart cards. The wizard can also be used by an administrator or users themselves in recovery situations. This method is more efficient than decrypting and reencrypting files.

Preventing exploits

Windows Vista uses Address Space Layout Randomization (ASLR) to load system files at random addresses in memory.[5] By default, all system files are loaded randomly at any of the possible 256 locations. Other executables have to specifically set a bit in the header of the Portable Executable (PE) file, which is the file format for Windows executables, to use ASLR. For such executables, the stack and heap allocated is randomly decided. By loading system files at random addresses, it becomes harder for malicious code to know where privileged system functions are located, thereby making it unlikely for them to predictably use them. This helps prevent most remote execution attacks by preventing Return-to-libc buffer overflow attacks.

The Portable Executable format has been updated to support embedding of exception handler address in the header. Whenever an exception is thrown, the address of the handler is verified with the one stored in the executable header. If they match, the exception is handled, otherwise it indicates that the run-time stack has been compromised, and hence the process is terminated.

Function pointers are obfuscated by XOR-ing with a random number, so that the actual address pointed to is hard to retrieve. So would be to manually change a pointer, as the obfuscation key used for the pointer would be very hard to retrieve. Thus, it is made hard for any unauthorized user of the function pointer to be able to actually use it. Also metadata for heap blocks are XOR-ed with random numbers. In addition, check-sums for heap blocks are maintained, which is used to detect unauthorized changes and heap corruption. Whenever a heap corruption is detected, the application is killed to prevent successful completion of the exploit.

Windows Vista binaries include intrinsic support for detection of stack-overflow. When a stack overflow in Windows Vista binaries is detected, the process is killed so that it cannot be used to carry on the exploit. Also Windows Vista binaries place buffers higher in memory and non buffers, like pointers and supplied parameters, in lower memory area. So to actually exploit, a buffer underrun is needed to gain access to those locations. However, buffer underruns are much less common than buffer overruns.

Data Execution Prevention

Windows Vista offers full support for the NX (No-Execute) feature of modern processors. [6] DEP was introduced in Windows XP Service Pack 2 and Windows Server 2003 Service Pack 1. This feature, present as NX (EVP) in AMD's AMD64 processors and as XD (EDB) in Intel's processors, can flag certain parts of memory as containing data instead of executable code, which prevents overflow errors from resulting in arbitrary code execution.

If the processor supports the NX-bit, Windows Vista automatically enforces hardware-based Data Execution Prevention on all processes to mark some memory pages as non-executable data segments (like the heap and stack), and subsequently any data is prevented from being interpreted and executed as code. This prevents exploit code from being injected as data and then executed.

If DEP is enabled for all applications, users gain additional resistance against zero-day exploits. But not all applications are DEP-compliant and some will generate DEP exceptions. Therefore, DEP is not enforced for all applications by default in 32-bit versions of Windows and is only turned on for critical system components. However, Windows Vista introduces additional NX policy controls that allow software developers to enable NX hardware protection for their code, independent of system-wide compatibility enforcement settings. Developers can mark their applications as NX-compliant when built, which allows protection to be enforced when that application is installed and runs. This enables a higher percentage of NX-protected code in the software ecosystem on 32-bit platforms, where the default system compatibility policy for NX is configured to protect only operating system components. For x86-64 platforms, backward compatibility is not an issue and therefore DEP is enforced by default for all programs. Also, only processor-enforced DEP is used in x86-64 versions of Windows Vista for greater security.

Digital Rights Management

Microsoft is introducing a number of Digital Rights Management and content-protection features in Windows Vista, to help digital content providers and corporations protect their data from being copied.

* PUMA: Protected User Mode Audio (PUMA) is the new User Mode Audio (UMA) audio stack. Its aim is to provide an environment for audio playback that restricts the copying of copyrighted audio, and restricts the enabled audio outputs to those allowed by the publisher of the protected content.[7]
* Protected Video Path - Output Protection Management (PVP-OPM) is a technology that prevents copying of protected digital video streams, or their display on video devices that lack equivalent copy protection (typically HDCP). Microsoft claims that without these restrictions the content industry may prevent PCs from playing copyrighted content by refusing to issue license keys for the encryption used by HD DVD, Blu-Ray Disc, or other copy-protected systems.[7]
* Protected Video Path - User-Accessible Bus (PVP-UAB) is similar to PVP-OPM, except that it applies encryption of protected content over the PCI Express bus.
* Rights Management Services (RMS) support, a technology that will allow corporations to apply DRM-like restrictions to corporate documents, email, and intranets to protect them from being copied, printed, or even opened by people not authorized to do so.
* Windows Vista introduces a Protected Process [8], which differs from usual processes in the sense that other processes cannot manipulate the state of such a process, nor can threads from other processes be introduced in it. A Protected Process has enhanced access to DRM-functions of Windows Vista. However, currently, only the applications using Protected Video Path can create Protected Processes.

These Digital Rights Management features have been criticised by some as more restrictive than useful for the user.

Application isolation

Windows Vista introduces Mandatory Integrity Control to set integrity levels for processes. A low integrity process can not access the resources of a higher integrity process. This feature is being used to enforce application isolation, where applications in a medium integrity level, such as all applications running in the standard user context can not hook into system level processes which run in high integrity level, such as administrator mode applications but can hook onto lower integrity processes like Windows Internet Explorer 7 or 8 (the latter of which is in beta, as of August 31, 2008). A lower privilege process cannot perform a window handle validation of higher process privilege, cannot SendMessage or PostMessage to higher privilege application windows, cannot use thread hooks to attach to a higher privilege process, cannot use Journal hooks to monitor a higher privilege process and cannot perform DLL–injection to a higher privilege process.