System File Checker (SFC) is a Microsoft Windows utility that allows a user to find and repair damage to Windows system files . The component is available in Windows 98 , Windows 2000 and all subsequent versions of the Windows NT family of operating systems . In Windows Vista and Windows 7, system file checking is built into Windows resource protection , which protects not only critical system files, but also registry keys and folders . Under Windows Vista , sfc.exe can be used to check specific paths, including the Windows folder and the download folder .
Windows file protection works by registering a notification of file changes in the login program . If any changes to protected system files are detected, then their original version is restored from the compressed folder %WinDir%\System32\dllcache . Resource Protection Windows sets the DACL and ACL for protected resources. Rights for full access to them belong to the service for installing Windows modules TrustedInstaller.exe . Administrators can no longer modify system files.
Content
History
Due to problems with Windows applications that can overwrite Windows 95 system files, Microsoft has created several security measures to protect system files from malicious attacks, damage, or such problems as the DLL hell .
System File Checker first appeared in Windows 98 as a utility with a GUI . She suggested scanning and recovering damaged system files by matching current versions of the original file versions contained in the database . This method of protection was basic. He identified system files by extension and location. It was possible to recover files from the installation disk or from a location specified by the user. Windows 98 did not offer any real-time protection methods other than file attributes; for this reason no preventive measures were available.
All Windows NT operating systems , starting with Windows 2000 , have provided real-time file protection, called Windows file protection . [one]
In addition, the system file sfc.exe ( sfc.exe ) has been redefined as a more powerful command line utility integrated with Windows file protection . Unlike SFC in Windows 98, it scans protected system files using Windows file protection and allows you to automatically restore them from the DLLCache folder or from the installation disk.
SFC was not in Windows ME , [2] system file protection was used instead. It, like Windows file protection, provided real-time protection.
Versions
The system file scan component that is included with Windows 2000 with a Service Pack of less than 4 is known for revoking patches provided by Microsoft . [3] The problem was fixed in Windows 2000 Service Pack 4.
Application
On Windows NT operating systems , the system file check can be started via the command line by running the following command:
sfc / scannow
If a problem is found, an attempt will be made to replace the problematic file with a file from the DLL cache ( %WinDir%\System32\Dllcache\ ). If there is no necessary file or the DLL cache is damaged, the user will be prompted to insert the Windows installation disc or specify the path to the file. The system file checker determines the initial installation path for Windows based on the SourcePath and ServicePackSourcePath registry SourcePath . [4] This may require an installation disc. [five]
With Windows Vista, files are protected by ACLs , but despite this, the command has not changed its meaning.
Starting from Windows Vista , system file checker can scan specific files. Also, the scan can be carried out in another Windows installation folder to replace damaged files (in case Windows does not boot). To run such a scan, you must run the system file checker from a different working installation of Windows Vista and later or from the Windows installation DVD , from where you can access the Windows recovery environment.
In the case when the component store is damaged, in Windows Vista and 7 you can install the CheckSUR tool, which checks the store and restores the detected damage. With Windows 8 , CheckSUR functionality is built into DISM .
Notes
- ↑ Description of the Windows file protection mechanism
- ↑ System file protection
- ↑ SFC / scannow may overwrite patch files
- ↑ When running the system file checker program with the scannow parameter in Windows XP with Service Pack 2 (SP2) and Windows Server 2003, the program cannot process the paths to network folders containing the installation CD
- ↑ You are prompted to insert a Windows XP SP2 CD when you try to run the System File Checker tool on a Windows XP SP2-based computer