HOW TO: Use Cipher.exe to Overwrite Deleted Data in Windows Server 2003 (814599)


The information in this article applies to:

  • Microsoft Windows Server 2003, Datacenter Edition
  • Microsoft Windows Server 2003, Enterprise Edition
  • Microsoft Windows Server 2003, Standard Edition
  • Microsoft Windows Server 2003, Web Edition
  • Microsoft Windows XP 64-Bit Edition Version 2003
  • Microsoft Windows Small Business Server 2003, Standard Edition
  • Microsoft Windows Small Business Server 2003, Premium Edition
For a Windows 2000 version of this article, see the following Knowledge Base article:

315672 HOW TO: Use Cipher.exe to Overwrite Deleted Data in Windows

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SUMMARY

Administrators can use Cipher.exe to encrypt and decrypt data on drives that use the NTFS file system and to view the encryption status of files and folders from a command prompt. The version of Cipher.exe that is included with Windows Server 2003 includes the ability to overwrite data that you have deleted so that it cannot be recovered or accessed.

When you delete files or folders, the data is not initially removed from the hard disk. Instead, the space on the disk that was occupied by the deleted data is "deallocated." After it is deallocated, the space is available for use when new data is written to the disk. Until the space is overwritten, you can recover the deleted data by using a low-level disk editor or data-recovery software.

When you encrypt plain text files, Encrypting File System (EFS) makes a backup copy of the file so that the data is not lost if an error occurs during the encryption process. After the encryption is complete, the backup copy is deleted. As with other deleted files, the data is not completely removed until it has been overwritten. The Windows Server 2003 version of the Cipher utility is designed to prevent unauthorized recovery of such data.

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How to Use the Cipher Security Tool to Overwrite Deleted Data

To overwrite deleted data on a volume by using Cipher.exe, use the /w switch with the cipher command:
  1. Quit all programs.
  2. Click Start, click Run, type cmd, and then press ENTER.
  3. Type cipher /w:folder, and then press ENTER, where folder is any folder in the volume that you want to clean. For example, the cipher /w:c:\test command causes all deallocated space on drive C to be overwritten. If C:\folder is a Mount Point or points to a folder on another volume, all deallocated space on that volume will be cleaned.
Data that is not allocated to files or folders is overwritten. This permanently removes the data. This can take a long time if you are overwriting a large amount of space.

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REFERENCES

For additional information about related topics, click the following article numbers to view the articles in the Microsoft Knowledge Base:

298009 Cipher.exe Security Tool for the Encrypting File System

223316 Best Practices for the Encrypting File System

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Modification Type:MinorLast Reviewed:3/30/2004
Keywords:kbSecurityServices kbHOWTOmaster KB814599 kbAudITPRO
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