__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Capability
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INFORMATION BULLETIN
Microsoft Unchecked Buffer in RAS Phonebook Vulnerability
[Microsoft Security Bulletin MS02-029]
June 13, 2002 19:00 GMT Number M-090
[Revised 21 June 2002]
[Revised 3 July 2002]
______________________________________________________________________________
PROBLEM: A flaw exists in the Remote Access Service (RAS) phonebook
implementation. The flaw is susceptible to a buffer overrun.
PLATFORM: * Windows NT 4.0
* Windows NT 4.0 Terminal Server Edition
* Windows 2000
* Windows XP
* Microsoft Routing and Remote Access Server, which can be
installed on Windows NT 4.0 Service Pack 6 or NT 4.0 Terminal
Server Edition Service Pack 6.
DAMAGE: Exploitation of this vulnerability can lead to either of two
things: (1) Causing a system failure. (2) Running code on the
system with LocalSystem privileges.
SOLUTION: Apply appropriate patches as prescribed by Microsoft's security
bulletin.
______________________________________________________________________________
VULNERABILITY The risk is MEDIUM. This is a local privilege elevation
ASSESSMENT: vulnerability. A malicious user must have the ability to
interactively log on to a system. An attacker who successfully
exploited this vulnerability could gain complete control over
the machine, thereby gaining the ability to take any desired
action on the machine.
______________________________________________________________________________
LINKS:
CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/m-090.shtml
ORIGINAL BULLETIN:
http://www.microsoft.com/technet/treeview/
default.asp?url=/technet/security/
bulletin/MS02-029.asp
______________________________________________________________________________
[***** Start Microsoft Security Bulletin MS02-029 *****]
Microsoft Security Bulletin MS02-029
Unchecked Buffer in Remote Access Service Phonebook Could Lead to Code
Execution (Q318138)
Originally posted: June 12, 2002
Updated: July 2, 2002 (Version 2.0)
Summary
Who should read this bulletin: Customers using Microsoft® Windows NT®,
Windows® 2000 and Windows XP.
Impact of vulnerability: Local privilege elevation.
Maximum Severity Rating: Critical
Recommendation: Administrators should apply the patch to immediately to machines
that allow unprivileged users to log onto them interactively such as workstations
and Terminal Servers.
Affected Software:
* Microsoft Windows NT 4.0
* Microsoft Windows NT 4.0 Terminal Server Edition
* Microsoft Windows 2000
* Microsoft Windows XP
* Microsoft Routing and Remote Access Server, which can be installed on Windows
NT 4.0 Service Pack 6 or NT 4.0 Terminal Server Edition Service Pack 6.
Technical details
Technical description:
On June 12, 2002, Microsoft released the original version of this bulletin. On July 2, 2002, the
bulletin was updated to reflect the availability of a revised patch. Although the original patch
completely eliminated the vulnerability, it had the side effect of preventing non-administrative users
from making VPN connections in some cases. The revised patch correctly handles VPN
connections. The revised patch is immediately available from the Download Center and will be
soon made available via WindowsUpdate.
The Remote Access Service (RAS) provides dial-up connections between computers and
networks over phone lines. RAS is delivered as a native system service in Windows
NT 4.0, Windows 2000 and Windows XP, and also is included in a separately
downloadable Routing and Remote Access Server (RRAS) for Windows NT 4.0. All of
these implementations include a RAS phonebook, which is used to store information
about telephone numbers, security, and network settings used to dial-up remote
systems.
A flaw exists in the RAS phonebook implementation: a phonebook value is not properly
checked, and is susceptible to a buffer overrun. The overrun could be exploited for
either of two purposes: causing a system failure, or running code on the system with
LocalSystem privileges. If an attacker were able to log onto an affected server and
modify a phonebook entry using specially malformed data, then made a connection using
the modified phonebook entry, the specially malformed data could be run as code by
the system.
Mitigating factors:
* The vulnerability could only be exploited by an attacker who had the appropriate
credentials to log onto an affected system.
* Best practices suggests that unprivileged users not be allowed to interactively log
onto business-critical servers. If this recommendation has been followed machines such
as domain controllers, ERP servers, print and file servers, database servers, and
others would not be at risk from this vulnerability.
Severity Rating: Internet Servers Intranet Servers Client Systems
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Windows NT 4.0 Low Low Moderate
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Windows NT 4.0
Routing and
Remote Access
Server Low Low Moderate
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Windows NT 4
Terminal Server
Edition Low Critical None
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Windows NT 4
Terminal Server
Edition, Routing
and Remote Access
Server Low Critical None
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Windows 2000 Low Critical Moderate
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Windows XP Low Low Moderate
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
The above assessment is based on the types of systems affected by the vulnerability,
their typical deployment patterns, and the effect that exploiting the vulnerability
would have on them. The attacker must have credentials to logon to the computer
where the RAS phonebook is held.
Vulnerability identifier: CAN-2002-0366
Tested Versions:
Microsoft tested Windows NT4.0, Windows NT 4.0 Terminal Server Edition, Windows 2000,
and Windows XP to assess whether they are affected by this vulnerability. Previous
versions are no longer supported, and may or may not be affected by these
vulnerabilities.
Patch availability
Download locations for this patch
* Microsoft Windows NT 4.0:
http://www.microsoft.com/ntserver/nts/downloads/security/q318138/default.asp
* Microsoft Windows NT 4.0 running RRAS (English Only):
http://www.microsoft.com/ntserver/nts/downloads/security/q318138/default.asp
* Microsoft Windows NT 4.0 Terminal Server Edition:
http://www.microsoft.com/ntserver/terminalserver/downloads/security/q318138/default.asp
* Microsoft Windows NT 4.0 Terminal Server Edition running RRAS (English Only):
http://www.microsoft.com/ntserver/terminalserver/downloads/security/q318138/default.asp
* Microsoft Windows 2000:
http://www.microsoft.com/windows2000/downloads/security/q318138/default.asp
* Microsoft Windows XP:
http://www.microsoft.com/downloads/release.asp?ReleaseID=38833
* Microsoft Windows XP 64-bit Edition:
http://www.microsoft.com/downloads/release.asp?ReleaseID=39011
Additional information about this patch
Installation platforms:
* The Windows NT 4.0 patch can be installed on systems running Service Pack 6a.
* The Windows Routing and Remote Access Server patch can be installed on systems running
Windows NT 4.0 Service Pack 6a (English only).
* The Windows NT 4.0 Terminal Server Edition patch can be installed on systems running
Windows NT 4.0 Terminal Server Edition Service Pack 6.
* The Windows NT 4.0 Terminal Server Edition, Routing and Remote Access Server patch can be
installed on systems running Windows NT 4.0 Terminal Server Edition Service Pack 6.
* The Windows 2000 patch can be installed on systems running Windows 2000 Service Pack 1 or
Windows 2000 Service Pack 2.
* The patch for Windows XP can be installed on systems running Windows XP Gold.
Inclusion in future service packs:
* The fix for this issue will be included in Windows 2000 Service Pack 3.
* The fix for this issue will be included in Windows XP Service Pack 1.
Reboot needed: Yes
Superseded patches: None.
Verifying patch installation:
Windows NT 4.0 Service Pack 6a:
* To verify that the patch has been installed on the machine, confirm that the following
registry key has been created on the machine:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Hotfix\Q318138
* To verify the individual files, consult the file manifest in Knowledge Base article
Q318138.
Windows NT 4.0 Terminal Server Edition Service Pack 6:
* To verify that the patch has been installed on the machine, confirm that the following
registry key has been created on the machine:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Hotfix\Q318138
* To verify the individual files, consult the file manifest in Knowledge Base article
Q318138.
Windows 2000 Service Pack 2:
* To verify that the patch has been installed on the machine, confirm that the following
registry key has been created on the machine:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows 2000\SP3\Q318138
* To verify the individual files, use the date/time and version information provided in the
following registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Updates\Windows 2000\SP3\Q318138\Filelist
Windows XP:
* To verify that the patch has been installed, confirm that the following registry key
has been created on the machine: HKLM\Software\Microsoft\Updates\Windows XP\SP1\Q318138
* To verify the individual files, use the date/time and version information provided in the
following registry key: HKLM\Software\Microsoft\Updates\Windows XP\SP1\Q318138\Filelist
Caveats:
None
Localization:
Localized versions of this patch are currently available at the locations listed above in
"Patch Availability".
Obtaining other security patches:
Patches for other security issues are available from the following locations:
* Security patches are available from the Microsoft Download Center, and can be most easily
found by doing a keyword search for "security_patch".
* Patches for consumer platforms are available from the WindowsUpdate web site
* All patches available via WindowsUpdate also are available in a redistributable form from
the WindowsUpdate Corporate site.
Other information:
Acknowledgments
Microsoft thanks Mark Litchfield of Next Generation Security Software Ltd. for reporting this
issue to us and working with us to protect customers.
Support:
* Microsoft Knowledge Base article Q318138 discusses this issue and will be available
approximately 24 hours after the release of this bulletin. Knowledge Base articles can be
found on the Microsoft Online Support web site.
* Technical support is available from Microsoft Product Support Services. There is no
charge for support calls associated with security patches.
Security Resources: The Microsoft TechNet Security Web Site provides additional information
about security in Microsoft products.
Disclaimer:
The information provided in the Microsoft Knowledge Base is provided "as is" without warranty
of any kind. Microsoft disclaims all warranties, either express or implied, including the
warranties of merchantability and fitness for a particular purpose. In no event shall
Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct,
indirect, incidental, consequential, loss of business profits or special damages, even if
Microsoft Corporation or its suppliers have been advised of the possibility of such damages.
Some states do not allow the exclusion or limitation of liability for consequential or
incidental damages so the foregoing limitation may not apply.
Revisions:
- V1.0 (June 12, 2002): Bulletin Created.
- V1.1 (June 20, 2002): Caveats section updated to include information regarding an issue
with the patch and VPN connections.
- V1.2 (July 1, 2002): Caveats section updated to clarify that the patch has been removed
from WindowsUpdate.
- V2.0 (July 2, 2002): Updated with revised patch that correctly handles VPN connections.
[***** End Microsoft Security Bulletin MS02-029 *****]
_______________________________________________________________________________
CIAC wishes to acknowledge the contributions of Microsoft Corporation for the
information contained in this bulletin.
_______________________________________________________________________________
CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
Institutes of Health (NIH). CIAC is located at the Lawrence Livermore
National Laboratory in Livermore, California. CIAC is also a founding
member of FIRST, the Forum of Incident Response and Security Teams, a
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among computer security teams worldwide.
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can be contacted at:
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E-mail: ciac@ciac.org
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PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
communities receive CIAC bulletins. If you are not part of these
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constituencies can be obtained via WWW at http://www.first.org/.
This document was prepared as an account of work sponsored by an
agency of the United States Government. Neither the United States
Government nor the University of California nor any of their
employees, makes any warranty, express or implied, or assumes any
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