Security and safety features new to Windows Vista
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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.
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[edit] 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. Any application requesting elevation has to have focus before the switch to Secure Desktop occurs. Else its taskbar icon blinks, and when focussed, the elevation UI is presented. Since the Secure Desktop allows only highest privilege System applications to run, no user mode application can present its dialog boxes, so any prompt for elevation consent can be safely assumed to be genuine. Additionally, they 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.
Many applications break for standard users (non-admins) today because they attempt to write to protected areas that the standard user does not have access to. UAC will improve application compatibility for these users by redirecting 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\.” To make it easier to find these redirected files has been added a new button to Windows Explorer. If there is a virtualized version of a file related to the current directory, a Compatibility Files button appears that will take you to the virtual location to view that file.
[edit] 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.
[edit] Parental controls
Windows Vista includes a range of parental controls. 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.
- Time limitations on when the account may be used
- 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
- Activity reports to monitor what was done under Parental Controls
[edit] Preventing exploits
Windows Vista uses Address Space Layout Randomization (ASLR) to load system files at random addresses in memory[2]. 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 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 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.
Windows Vista also uses processor-enforced 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. Though DEP was present in Windows XP Service Pack 2 and Windows Server 2003 Service Pack 1, its enforcement has been made stricter in Windows Vista.
[edit] Digital Rights Management
Microsoft is introducing a number of Digital Rights Management and content-protection features in Windows Vista, to help digital content providers, corporations, and end-users 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[3].
- 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[3].
- 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. MSN Spaces will also offer an open RMS server that home users and smaller businesses can use to extend this ability to their own documents.[citation needed]
[edit] 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.
[edit] Service hardening
A new security feature called Windows Service Hardening prevents Windows services from doing operations on file systems, registry or networks[4] which they are not supposed to, thereby preventing entry of malware by piggybacking on system services. Services are now assigned a per-service Security identifier (SID), which allows controlling access to the service as per the access specified by the security identifier. Services can also use access control lists (ACL) to prevent external access to resources private to itself. Services in Windows Vista also run in a less privileged account such as Local Service or Network Service, instead of the System account. Services will also need explicit write permissions to write to resources, on a per-service basis. Only those resources which have to be modified by a service give it write access. So trying to modify any other resource fails. Services will also have pre-configured firewall policy, which gives it only as much privilege as is needed for it to function properly.
[edit] Network Access Protection
Network Access Protection, (NAP) which makes sure that computers connecting to a network or communicating over a network conform to a required level of system health, as has been set by the administrator of the network, has been upgraded significantly in Windows Vista. Depending on the policy set by the administrator, the computers which do not meet the requirements will either be warned and granted access or allowed a limited access to network resources or completely denied access. NAP can also optionally provide software updates to a non-compliant computer to upgrade itself to the level as required to access the network, using a Remediation Server. A conforming client is given a Health Certificate, which it then uses to access protected resources on the network.
A Network Policy Server, running Windows Server "Longhorn" acts as health policy server and clients need to use Windows Vista or better. A VPN server, RADIUS server or DHCP server can also act as the health policy server.
[edit] x86-64 -specific features
- Data Execution Prevention (DEP) uses only the NX-bit support in processors, with no fallback software emulation. This ensures that the less effective software-enforced DEP (which is only safe exception handling) is not used. In 32 bit versions, however, software-enforced DEP is an option.
- An upgraded Kernel Patch Protection, also referred to as PatchGuard, prevents third-party software, including kernel-mode drivers from modifying the kernel, or any data structure used by the kernel, in any way; if any modification is detected, the system is shutdown. This mitigates a common tactic used by rootkits to hide themselves from user-mode applications.[5] PatchGuard was first introduced in the x64 edition of Windows Server 2003 Service Pack 1, and was included in Windows XP Professional x64 edition.
- Code Integrity check-sums signed code. Before loading such code, it is verified against the check-sum to ensure it has not modified.
[edit] Other features
A number of specific changes have been made:
- Windows Resource Protection prevents "potentially damaging system configuration changes"[6], by preventing change to system files and settings by any process other than Windows Installer. Also changes to registry by unauthorized software are blocked.
- Protected-Mode IE: Internet Explorer runs in a separate, low-privilege process, protecting the user from malicious content and security vulnerabilities, even in ActiveX controls.
- Windows Firewall has been upgraded to support outbound packet filtering and full IPv6 support. A new MMC-based interface has been introduced which offers much more advanced control over the firewall[7].
- Session 0 Isolation: Previous versions of Windows ran System services in the same login session as the locally logged-in user (Session 0). In Windows Vista, Session 0 is now reserved for these services, and all interactive logins are done in other sessions.[8] This is intended to help mitigate a class of exploits of the Windows message-passing system, known as Shatter attacks.
- Full support for the "NX" (No-Execute) feature of modern processors. 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.
- Address Space Layout Randomization (ASLR) to prevent Return-to-libc buffer overflow attacks.
- BitLocker Drive Encryption. Formerly known as "Secure Startup", this software utilizes a Trusted Platform Module (compliant with the 1.2 version of the TCG specifications) to improve PC security. It ensures that the PC running Windows Vista starts in a known-good state, and it also protects data from unauthorized access through full volume encryption[9]. 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 Vista can use Smart Cards or Smart Card/Password combo for user authentication.
- Windows Vista can use smart cards to store Encrypting File System (EFS) keys. This makes sure that encrypted files are accessible only as long as the smart card is physically available.
