iDefense Security Advisory 06.13.06: Windows MRXSMB.SYS MRxSmbCscIoctlOpenForCopyChunk Overflow

2006-06-14T00:00:00
ID SECURITYVULNS:DOC:13147
Type securityvulns
Reporter Securityvulns
Modified 2006-06-14T00:00:00

Description

Windows MRXSMB.SYS MRxSmbCscIoctlOpenForCopyChunk Overflow

iDefense Security Advisory 06.13.06 http://www.idefense.com/application/poi/display?type=vulnerabilities June 13, 2006

I. BACKGROUND

Microsoft Windows Operating System is system software for Intel based PCs. More information can be found at the vendor website:

http://www.microsoft.com

II. DESCRIPTION

Local exploitation of a buffer overflow vulnerability in Microsoft Corp.'s Windows Operating System could allow attackers to gain SYSTEM privileges.

The vulnerability specifically exists due to a logic error in the Microsoft Client Side Caching (CSCDLL.DLL) and Microsoft Server Message Block Redirector Driver (MRXSMB.SYS) code. The Microsoft Client Side Caching infrastructure provides the user-mode portion of the "offline files" subsystem, which allows interaction with network files while offline and preserves file system permissions. The Microsoft Server Message Block Redirector Driver is the kernel-mode file system driver that provides the network redirector functionality utilized by CSC.

MRXSMB.SYS functions are exposed via IOCTL commands. An access validation error exists in the MrxSmbCscIoctlOpenForCopyChunk() function. In order to establish communication with the MRXSMB subsystem, a file handle to a shadow device is created and DeviceIoControl() is used to issue commands. If an attacker utilizes the METHOD_NEITHER method flag, the address will be unchecked and an overwrite of kernel memory can occur resulting in ring0 code execution.

III. ANALYSIS

Successful exploitation of this vulnerability could result in elevation to SYSTEM privileges.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in Microsoft Windows XP SP2. It is suspected that all versions of Microsoft Windows are vulnerable.

V. WORKAROUND

iDefense is unaware of any effective workaround for this issue.

VI. VENDOR RESPONSE

The vendor security advisory and appropriate patches are available at:

http://www.microsoft.com/technet/security/Bulletin/MS06-030.mspx

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CAN-2006-2373 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org), which standardizes names for security problems.

VIII. DISCLOSURE TIMELINE

12/09/2005 Initial vendor notification 12/13/2005 Initial vendor response 06/13/2006 Coordinated public disclosure

IX. CREDIT

iDefense credits Rubén Santamarta with the discovery of this vulnerability.

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X. LEGAL NOTICES

Copyright © 2006 iDefense, Inc.

Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please email customerservice@idefense.com for permission.

Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.