Server for NFS clears or does not permit you to set the Setuid bit or the Setgid bit (825137)


The information in this article applies to:

  • Microsoft Windows Services for UNIX 3.0
  • Microsoft Windows Services for UNIX 2.3 OEM Only

SYMPTOMS

For files and directories that are group writable or group executable or world writable or world executable, you may experience the following symptoms:
  • If you set either the setuid bit or the setgid bit, when you make the file or directory to be group writable or group executable or world writable or world executable, the bit is cleared.
  • If the file or directory is already group writable or group executable or world writable or world executable, you cannot set the setuid and setgid bits.

RESOLUTION

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
    Date         Time   Version            Size    File name
   --------------------------------------------------------------
   01-Aug-2003  06:37  7.0.1701.20        23,040  Dsctrs.dll       
   01-Aug-2003  06:37  7.0.1701.20        25,088  Nfsonly.exe      
   01-Aug-2003  06:37  7.0.1701.20        67,072  Nfssh.dll        
   01-Aug-2003  06:37  7.0.1701.20        88,576  Nfsshare.exe     
   01-Aug-2003  06:37  7.0.1701.20       143,872  Nfsshex.dll      
   01-Aug-2003  06:37  7.0.1701.20       114,176  Nfssprop.dll     
   01-Aug-2003  06:37  7.0.1701.20        97,280  Nfssvc.exe       
   01-Aug-2003  06:37  7.0.1701.20       325,312  Nfssvr.sys
   01-Aug-2003  06:37  7.0.1701.20       323,488  Nfssvrn4.sys
   01-Aug-2003  06:37  7.0.1701.20        42,624  Portmap.sys
   01-Aug-2003  06:37  7.0.1701.20        73,056  Rpcxdr.sys

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section of this article.

MORE INFORMATION

As a result of the Microsoft Trustworthy Computing Initiative, Server for NFS has been changed to fix a known security issue in UNIX. Server for NFS masks out certain mode bits to fix an issue that occurs when a file or directory has the setuid bit or the setgid bit behavior enabled and when the file or the directory is either group writable or world writable.

The exploitation of the situation is when an intruder overwrites the binary with a Trojan horse and then executes the binary. The binary runs with the rights of the owner, instead of running as the intruder.

Some customers may find this security update problematic because the security update deviates from UNIX behavior, although this behavior is not specified in the Network File System (NFS) RFC.

The bit masking occurs only if the file or directory has both of the following characteristics:
  • One or both of the following bits is set:setgid or setuid.
  • Group writable or group executable or world writable or world executable.
This hotfix creates the following registry value:

HKLM\System\CurrentControlSet\Services\NfsSvr\Parameters\SafeSetUidGidBits

This registry value controls whether the setuid bit and the setgid bit are masked for security reasons. Settings may be as follows:
  • The default data for this registry value is 1.
  • A value of 1 causes the bits to be masked out for security reasons.
  • A value of 0 causes the standard UNIX behavior.
This hotfix also turns off bit masking for the setuid bit and the setgid bit for directories because directories cannot be executed. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Modification Type:MinorLast Reviewed:10/25/2005
Keywords:kbHotfixServer kbQFE kbQFE kbfix kbbug KB825137 kbAudITPRO
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