How to use Encrypting File System (EFS) with Internet Information Services (243756)


The information in this article applies to:

  • Microsoft Internet Information Services 5.0
This article was previously published under Q243756
We strongly recommend that all users upgrade to Microsoft Internet Information Services (IIS) version 6.0 running on Microsoft Windows Server 2003. IIS 6.0 significantly increases Web infrastructure security. For more information about IIS security-related topics, visit the following Microsoft Web site:

http://www.microsoft.com/technet/security/prodtech/IIS.mspx

SUMMARY

Microsoft Windows 2000 employs a security technology named Encrypting File System (EFS), which enables users to encrypt and decrypt files. Windows users can utilize EFS to keep sensitive files safe from unauthorized access. This article summarizes how to use this technology to encrypt personal Web documents for additional security.

MORE INFORMATION

Warning EFS will fail encryption attempts on files with the System attribute. Administrators should not attempt to defeat this safeguard to encrypt files in the system directory. The private keys needed for decryption are not available during the boot process. Therefore, a system will be rendered unusable if its system files are encrypted. Future releases of Windows may provide secure boot capabilities that support encryption of system files.

EFS is enabled for documents in Windows 2000 through an optional advanced file attribute. To implement this feature, follow these steps:
  1. In Windows Explorer, create a new folder named SecureTest in the root folder for your Web site.
  2. In the new folder, save the following Active Server Pages (ASP) code as Default.asp:
    <html>
<body>
You are logged on as:
&quot;<b><%=Request.ServerVariables("LOGON_USER")%></b>&quot;
</body>
</html>
  3. Right-click the Default.asp file and then click Properties.
  4. Click Advanced.
  5. Select the Encrypt contents to secure data check box.
  6. Click OK.
  7. If you are prompted to encrypt the parent folder, select the Encrypt the file only radio button and then click OK.
  8. Click OK again to return to Windows Explorer.
When you browse to the http://<servername>/SecureTest/default.asp page, the page requires authentication and your user name is displayed, even if anonymous authentication is enabled for the entire Web site. This is because files that are encrypted with EFS are private files, and only the user that encrypted the files can browse to them. The authentication method used may be Basic/Clear Text, Windows Integrated, or Digest, depending on how the Web site is configured.

The following is a list of best practices regarding EFS:
  • Protect the private keys associated with data recovery certificates. Export them into a Personal Information Exchange (.pfx) file protected with a strong password. Store .pfx files on a floppy disk, and lock the floppy disk away for safekeeping.
  • Encrypt folders rather than individual files. Explorer only allows encryption at the folder level. However, the Cipher.exe file can encrypt individual files. Applications work on files in various ways. For example, when a user edits a file with an application, the application may create temporary files in the same folder as the original. Encrypting at the folder level ensures that these temporary files are not created or saved as plain text.
  • Encrypt the My Documents folder (%UserProfile%\My Documents) to ensure that the personal folder, in which most Microsoft Office documents are saved, is encrypted by default.
  • Encrypt the Temp folder (%TEMP%) to ensure that the temporary files that are created by various applications are encrypted.

REFERENCES

For more information on Windows File Protection, click the following article number to view the article in the Microsoft Knowledge Base:

222193 Description of the Windows file protection feature

For more information on Web site authentication methods, click the following article numbers to view the articles in the Microsoft Knowledge Base:

264921 How IIS authenticates browser clients

222028 Setting up digest authentication for use with Internet Information Services 5.0

Modification Type:MinorLast Reviewed:6/16/2006
Keywords:kbinfo KB243756
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