The CHKDSK utility incorrectly identifies and deletes in-use security descriptors

For a Microsoft Windows 2000 version of this article, see 831375 .


When you run the chkdsk command in fix mode, and you use the /F switch or the /R switch with this command, access control lists (ACLs) on some files may revert to their default values. This problem may occur if the volume contains more than 4,194,303 files. For example, this problem occurs in the following Chkdsk output:
Checking file system on J:
The type of the file system is NTFS.
Volume label is MYVOLUME.

Cleaning up minor inconsistencies on the drive.
Cleaning up 1496 unused index entries from index $SII of file 0x9.
Cleaning up 1496 unused index entries from index $SDH of file 0x9.
Cleaning up 1496 unused security descriptors.
CHKDSK discovered free space marked as allocated in the
master file table (MFT) bitmap.
Windows has made corrections to the file system.

1576209407 KB total disk space.
1514676116 KB in 4232266 files.
1523236 KB in 302192 indexes.
0 KB in bad sectors.
4671195 KB in use by the system.
65536 KB occupied by the log file.
55338860 KB available on disk.

4096 bytes in each allocation unit.
394052351 total allocation units on disk.
13834715 allocation units available on disk.


This problem occurs because the Chkdsk utility may not find references to all the security IDs if the master file table is larger than 4 gigabytes (GB) or if there are more than 4,194,303 files on the volume. Therefore, the undiscovered security descriptors are reset.


We recommend that you immediately apply the appropriate service pack or hotfix on any computer that is currently vulnerable to the loss of security descriptors.

We recommend that you inventory servers and workstations in your organization and then install preventive software on any computers that are at risk. We recommend that you apply any preventive fix to new computers before you deploy the new computers for test or production use. We recommend that you inform server administrators, helpdesk administrators, and support professionals that they should install preventive fixes before the following operations are executed:
  • chkdsk /F
  • chkdsk /R
  • autochk
Note IT operations guides should also install preventive fixes before these commands are executed.

Windows Server 2003

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.


No prerequisites are required.

Restart requirement

You must restart your computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) 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 Platform
11-Dec-2003 19:21 5.2.3790.109 831,488 Untfs.dll IA64
11-Dec-2003 19:25 5.2.3790.109 308,224 Untfs.dll x86
25-Oct-2003 00:13 271 Branches.inf
11-Nov-2003 21:04 9,981
11-Nov-2003 20:45 354 Updatebr.inf
11-Nov-2003 20:45 5,972 Update_rtmqfe.inf

Windows XP

To resolve this problem, obtain the latest service pack for Windows XP. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

322389 How to obtain the latest Windows XP service pack


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

More Information

Even when this hotfix is installed, it is still possible for Chkdsk to reset permissions back to default settings. You can use the Vrfydsk.exe utility to determine whether real Security Descriptor file corruption occurs on a volume. You can save the Vrfydsk.exe utility output to a text file. If the resulting output file contains the following repair entry, the default security may be set on some files and directories.
CHKDSK is verifying security descriptors (stage 3 of 3)... Repairing the security file record segment. <----- REAL CORRUPTION OCCURRED Deleting an index entry with Id #### from index $SII of file 9. Deleting an index entry with Id #### from index $SII of file 9.

For more information about the vrfydsk.exe utility, click the following article number to view the article in the Microsoft Knowledge Base:

837326 How to use the Vrfydsk.exe tool to check a volume for errors without taking the volume offline in Windows Server 2003

For more 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

For more information about security descriptors, search Help and Support Center for "security descriptors."