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Q293826: Pattern-Matching Function Causes Access Violation on FTP Server

Article: Q293826
Product(s): Internet Information Server
Version(s): 4.0,5.0
Operating System(s): 
Keyword(s): kbSecurity kbWinNT400PreSP7Fix kbWin2000PreSP3Fix kbgraphxlinkcritical KbSECVulnerabili
Last Modified: 15-AUG-2002

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Internet Information Services version 5.0 
- Microsoft Internet Information Server version 4.0 
-------------------------------------------------------------------------------

SYMPTOMS
========

A denial of service (DoS) vulnerability exists in Microsoft Internet Information
Services (IIS) 5.0 and Microsoft Internet Information Server (IIS) 4.0 because
the function that processes wildcard sequences in FTP commands does not always
allocate sufficient memory when it performs pattern matching. Under unusual
circumstances, it may be possible for an attacker to levy an FTP command
containing a wildcard sequence that, when expanded, can overrun the allocated
memory and cause an access violation.

This scenario can cause the IIS service (which provides both Web and FTP
functionality) to fail. As a result, all Web or FTP sessions that are in
progress at the time are severed, and no new sessions can be established until
the IIS service is restarted. In IIS 5.0, the service restarts automatically. In
IIS 4.0, operator intervention is required to restart the service.

The attacker cannot add, change, or delete data on the server through this
vulnerability, nor can the attacker usurp any administrative privileges.

Mitigating Factor

The attacker must be able to start an FTP session in order to exploit the
vulnerability.

CAUSE
=====

This problem occurs because of a flaw in a pattern-matching function that is
used by at least one FTP command. Depending on the wildcard sequence that is
entered and the specific configuration of the server's file system, it is
possible for the resulting pattern to exceed the available memory and trigger an
access violation. This, in turn, causes the IIS service to fail.

RESOLUTION
==========

For additional information on what is fixed by the following patches, click the
article number below to view the article in the Microsoft Knowledge Base:

  Q297860 IIS 5.0 Security and Post-Windows NT 4.0 SP5 IIS 4.0 Patch Rollup

Internet Information Services 5.0
---------------------------------

To resolve this problem, obtain the latest service pack for Windows 2000. For
additional information, click the following article number to view the article
in the Microsoft Knowledge Base:

  Q260910 How to Obtain the Latest Windows 2000 Service Pack

The English version of this fix should have the following file attributes or
later:

  Date        Time    Version        Size     File name
  --------------------------------------------------------
  5/31/2001  03:31p  5.0.2195.3649  245,520    Adsiis.dll
  5/31/2001  03:31p  5.0.2195.3649  332,560    Asp.dll
  5/29/2001  04:37p  4.0.2.4701     593,976    Fp4autl.dll
  5/31/2001  03:31p  5.0.2195.3649  246,032    Httpext.dll
  5/31/2001  03:31p  5.0.2195.3649   56,592    Httpodbc.dll
  5/31/2001  03:31p  5.0.2195.3649  122,640    Iisrtl.dll
  5/31/2001  03:31p  5.0.2195.3649   13,584    Infoadmn.dll
  5/31/2001  03:31p  5.0.2195.3649  245,520    Infocomm.dll
  5/31/2001  03:31p  5.0.2195.3649   62,736    Isatq.dll
  5/31/2001  03:31p  5.0.2195.3649   46,352    Ism.dll
  5/31/2001  03:31p  5.0.2195.3649   76,560    Msw3prt.dll
  5/30/2001  03:40p  5.0.2195.3651     6928    Schmupd.exe
  5/30/2001  03:40p  5.0.2195.3651     7952    Spiisupd.exe
  5/31/2001  03:32p  5.0.2195.3649   41,232    Ssinc.dll
  5/31/2001  03:32p  5.0.2195.3649     7440    W3ctrs.dll
  5/31/2001  03:32p  5.0.2195.3649  353,040    W3svc.dll


Internet Information Server 4.0
-------------------------------

A supported fix is now available from Microsoft, but it is only intended to
correct the problem that is described in this article. Apply it only to
computers that you determine are at risk of attack. Evaluate your computer's
physical accessibility, network and Internet connectivity, and other factors to
determine the degree of risk to your computer. See the associated Microsoft
Security Bulletin
(http://www.microsoft.com/technet/security/bulletin/ms01-026.asp) to help
determine the degree of risk. This fix may receive additional testing. If your
computer is sufficiently at risk, Microsoft recommends that you apply this fix
now.

To resolve this problem immediately, download the fix by clicking the download
link later in this article or contact Microsoft Product Support Services to
obtain the fix. For a complete list of Microsoft Product Support Services phone
numbers and information about support costs, please visit the following
Microsoft Web site:

  http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

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 following file is available for download from the Microsoft Download Center:

  DownloadDownload Q295534i.exe now
  (http://www.microsoft.com/Downloads/Release.asp?ReleaseID=29787)
  NOTE: Q295534is.exe are the Symbols files.

For additional information about how to download Microsoft Support files, click
the following article number to view the article in the Microsoft Knowledge
Base:

  Q119591 How to Obtain Microsoft Support Files from Online Services

Microsoft scanned this file for viruses. Microsoft used the most current
virus-detection software that was available on the date that the file was
posted. The file is stored on secure servers that prevent any unauthorized
changes to the file.

The English version of this fix should have the following file attributes or
later:

  Date        Time    Version        Size     File name
  --------------------------------------------------------
  04/11/2001  01:32p  4.2.764.1      214,544  Adsiis.dll
  04/11/2001  01:33p  4.2.764.1      330,672  Asp.dll
  04/02/2001  04:55p  4.0.2.4701     593,976  Fp4autl.dll
  04/11/2001  01:32p  4.2.764.1       81,888  Ftpsvc2.dll
  04/11/2001  01:32p  4.2.764.1       55,392  Httpodbc.dll
  04/11/2001  01:32p  4.2.764.1       98,912  Iischema.dll
  04/11/2001  01:31p  4.2.764.1       63,472  Iislog.dll
  04/11/2001  01:31p  4.2.764.1      185,792  Infocomm.dll
  04/11/2001  01:31p  4.2.764.1       29,520  Iscomlog.dll
  04/11/2001  01:35p  4.2.764.1       54,560  Ism.dll
  04/02/2001  04:55p  4.0.1381.7086  375,056  Kernel32.dll
  04/11/2001  01:36p  4.2.764.1        9,680  Schmupd.exe
  04/11/2001  01:32p  4.2.764.1       38,256  Ssinc.dll
  04/11/2001  01:32p  4.2.764.1       25,360  Sspifilt.dll
  04/11/2001  01:32p  4.2.764.1      229,024  W3svc.dll
  04/11/2001  01:31p  4.2.764.1       88,032  Wam.dll

NOTE: You can install this patch on systems that are running Microsoft Windows NT
4.0 Service Pack 5 or Windows NT 4.0 Service Pack 6a.



STATUS
======

Internet Information Services 5.0
---------------------------------

Microsoft has confirmed that this problem may cause a degree of security
vulnerability in Internet Information Services 5.0. This problem was first
corrected in Windows 2000 Service Pack 3.

Internet Information Server 4.0
-------------------------------

Microsoft has confirmed that this problem may cause a degree of security
vulnerability in Internet Information Server 4.0.

MORE INFORMATION
================

For additional information about how to obtain a hotfix for Windows 2000
Datacenter Server, click the article number below to view the article in the
Microsoft Knowledge Base:

  Q265173 The Datacenter Program and Windows 2000 Datacenter Server Product

For additional information about how to install multiple hotfixes with only one
reboot, click the article number below to view the article in the Microsoft
Knowledge Base:

  Q296861 Use QChain.exe to Install Multiple Hotfixes with One Reboot

For more information on this vulnerability, see the following Microsoft Web
site:

  http://www.microsoft.com/technet/security/ms01-026

Additional query words: security_patch kbWin2000srp1

======================================================================
Keywords          : kbSecurity kbWinNT400PreSP7Fix kbWin2000PreSP3Fix kbgraphxlinkcritical KbSECVulnerability KbSECHack KbSECDOS kbWin2000sp3fix 
Technology        : kbiisSearch kbiis500 kbiis400
Version           : :4.0,5.0
Hardware          : x86
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================
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