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Cisco Security Advisory: Cisco CNS Network Registrar Denial of Service Vulnerability
From: Cisco Systems Product Security Incident Response Team <psirt () cisco com>
Date: Thu, 2 Dec 2004 08:00:00 -0800

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Cisco Security Advisory: Cisco CNS Network Registrar Denial of Service
Vulnerability
=============================================================================
Revision 1.0

For Public Release 2004 December 02 1600 UTC (GMT)

- -----------------------------------------------------------------------------

Contents

    Summary
    Affected Products
    Details
    Impact
    Software Versions and Fixes
    Obtaining Fixed Software
    Workarounds
    Exploitation and Public Announcements
    Status of This Notice: FINAL
    Distribution
    Revision History
    Cisco Security Procedures

- -------------------------------------------------------------------------------

Summary
=======

Cisco CNS Network Registrar Domain Name Service /Dynamic Host Configuration
Protocol (DNS/DHCP) server for the Windows Server platforms is vulnerable to a
Denial of Service attack when a certain crafted packet sequence is directed to
the server. Cisco has made free software available to address this
vulnerability for all affected customers.

The vulnerabilities are documented as the following Cisco Bug IDs: CSCeg27625
and CSCeg27614.

This advisory will be posted at http://www.cisco.com/warp/public/707/
cisco-sa-20041202-cnr.shtml.

This advisory will also be posted at the Cisco CNS Network Registrar internal
web site at: http://csg.cisco.com/nmtg/insmbu/products/cnr/index.cfm?qsolution=
CNR&qsection=Product+Bulletins.

Affected Products
=================

Vulnerable Products
- -------------------

Cisco CNS Network Registrar for Windows NT server and Windows 2000

Two issues are described in this advisory CSCeg27625 and CSCeg27614. Cisco CNS
Network Registrar version 6.0 through 6.1.1.3 are affected by CSCeg27625.
However, all versions upto and including version 6.1.1.3 are also affected by
CSCeg27614 .

Products Confirmed Not Vulnerable
- ---------------------------------

The following Cisco Network Registrar products are not vulnerable to the issues
described in this advisory:

  * Cisco Network Registrar for Unix
  * Cisco Network Registrar for Linux

No other Cisco products are currently known to be affected by these
vulnerabilities.

Details
=======

Cisco CNS Network Registrar is a DNS and DHCP server installed on Windows NT
servers and Windows 2000 servers. Two separate vulnerabilities may impact
system stability or availability if exploited. These issues are detailed below:

  * CSCeg27625 -The Cisco CNS Network Registrar CCM (Central Configuration
    Management) server may consume almost 100% of the system CPU when a remote
    user ends a connection after sending a specific sequence of packets. The
    server agent must be restarted to clear this condition.
  * CSCeg27614 -The Cisco CNS Network Registrar lock manager process may crash
    when the system receives an unexpected packet sequence. This will cause the
    CCM server to also fail. You must restart the server agent to resume normal
    operations.

These issues are unrelated to the recent Cisco Security Advisory regarding
Cisco IOS DHCP implementation. http://www.cisco.com/warp/public/707/
cisco-sa-20041110-dhcp.shtml These issues are also unrelated to the recent
UNIRAS advisory regarding DNS. http://www.uniras.gov.uk/l1/l2/l3/alerts2004/
alert-4004.txt

Impact
======

Exploitation of either CSCeg27625 or CSCeg27614 can result in a denial of
service attack, stemming from system resource starvation or unavailability.

Software Versions and Fixes
===========================

The two issues are fixed in the 6.1.1.4 patch release. Releases are available
for download to registered customers on CCO at: http://www.cisco.com/cgi-bin/
Software/Tablebuild/tablebuild.pl/nr-eval

Customers who are using Cisco Network Registrar 5.5 versions must request a new
license key for the Cisco CNS Network Registrar 6.1.1.x release before
obtaining the patched 6.1.1.4 release from CCO. Version 5.5 license keys are
incompatible with the Cisco CNS Network Registrar 6.0 or 6.1 software releases.
To request a new license key, any customer wishing to upgrade version 5.5 to
version 6.1 software should send an electronic mail message to 
cnr-psirt-update () cisco com, and provide the customer name, address, contact
name and existing version 5.5 license key string in the body of the message
along with a line indicating `CNR PSIRT upgrade for Windows request'. A new
license key will be dispatched via email to the requestor, allowing them to
install and upgrade to the patched 6.1.1.4 release using the new license key.

When considering software upgrades, please also consult http://www.cisco.com/
warp/public/707/advisory.html and any subsequent advisories to determine
exposure and a complete upgrade solution.

In all cases, customers should exercise caution to be certain the devices to be
upgraded contain sufficient memory and that current hardware and software
configurations will continue to be supported properly by the new release. If
the information is not clear, contact the Cisco Technical Assistance Center ("
TAC") for assistance. TAC contacts are as follows.

  * +1 800 553 2447 (toll free from within North America)
  * +1 408 526 7209 (toll call from anywhere in the world)
  * e-mail: tac () cisco com

Obtaining Fixed Software
========================

Customers with Service Contracts
- --------------------------------

Customers with contracts should obtain upgraded software through their regular
update channels. For most customers, this means that upgrades should be
obtained through the Software Center on Cisco's worldwide website at http://
www.cisco.com.

Customers using Third-party Support Organizations
- -------------------------------------------------

Customers whose Cisco products are provided or maintained through prior or
existing agreement with third-party support organizations such as Cisco
Partners, authorized resellers, or service providers should contact that
support organization for assistance with the upgrade, which should be free of
charge.

Customers without Service Contracts
- -----------------------------------

Customers who purchase direct from Cisco but who do not hold a Cisco service
contract and customers who purchase through third-party vendors but are
unsuccessful at obtaining fixed software through their point of sale should get
their upgrades by contacting the Cisco Technical Assistance Center (TAC). TAC
contacts are as follows.

  * +1 800 553 2447 (toll free from within North America)
  * +1 408 526 7209 (toll call from anywhere in the world)
  * e-mail: tac () cisco com

Please have your product serial number available and give the URL of this
notice as evidence of your entitlement to a free upgrade. Free upgrades for
non-contract customers must be requested through the TAC.

Please do not contact either "psirt () cisco com" or "security-alert () cisco com"
for software upgrades.

See http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional
TAC contact information, including special localized telephone numbers and
instructions and e-mail addresses for use in various languages. Customers may
only install and expect support for the feature sets they have purchased. By
installing, downloading, accessing or otherwise using such software upgrades,
customers agree to be bound by the terms of Cisco's software license terms
found at http://www.cisco.com/public/sw-license-agreement.html, or otherwise
set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/
sw-usingswc.shtml.

Workarounds
===========

These vulnerabilities can be mitigated by placing access lists on adjacent
network devices such as routers or firewalls to block inbound connections to
all high or ephemeral port numbers, including the CCM port.

If remote access to the Cisco CNS Network Registrar is required, it is
recommended that trusted hosts be explicitly permitted in access control lists,
and all other connection attempts blocked. Remote connection CLI ports are tcp
2875 & tcp 2876, and the default port number for CCM is tcp1234, which can also
be configured to a different port number. Access lists permitting selective
access to these ports from trusted IP addresses can mitigate this
vulnerability.

The effectiveness of any workaround is dependent on specific customer
situations such as product mix, network topology, traffic behavior, and
organizational mission. Due to the variety of affected products and releases,
customers should consult with their service provider or support organization to
ensure any applied workaround is the most appropriate for use in the intended
network before it is deployed.

Exploitation and Public Announcements
=====================================

The Cisco PSIRT is not aware of any public announcements or malicious use of
the vulnerability described in this advisory.

The discovery and documentation of this vulnerability was conducted by the
Qualys Security Research Team. More information about the Qualys Security
Research Team can be found at their website: http://www.qualys.com

Status of This Notice: FINAL
============================

THIS ADVISORY IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF
GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE 
OF THE INFORMATION ON THE ADVISORY OR MATERIALS LINKED FROM THE ADVISORY IS 
AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS NOTICE
AT ANY TIME.

A stand-alone copy or Paraphrase of the text of this Security Advisory that 
omits the distribution URL in the following section is an uncontrolled copy, 
and may lack important information or contain factual errors. 

Distribution
============

This advisory will be posted on Cisco's worldwide website at http://
www.cisco.com/warp/public/707/cisco-sa-20041202-cnr.shtml.

In addition to worldwide web posting, a text version of this notice is
clear-signed with the Cisco PSIRT PGP key and is posted to the following e-mail
and Usenet news recipients.

  * cust-security-announce () cisco com
  * first-teams () first org (includes CERT/CC)
  * bugtraq () securityfocus com
  * vulnwatch () vulnwatch org
  * cisco () spot colorado edu
  * cisco-nsp () puck nether net
  * full-disclosure () lists netsys com
  * comp.dcom.sys.cisco () newsgate cisco com

Future updates of this advisory, if any, will be placed on Cisco's worldwide
website, but may or may not be actively announced on mailing lists or
newsgroups. Users concerned about this problem are encouraged to check the
above URL for any updates.

Revision History
================

+---------------------------------------------+
| Revision | 2004-December-2 | Initial public |
| 1.0      |                 | release.       |
+---------------------------------------------+

Cisco Security Procedures
=========================

Complete information on reporting security vulnerabilities in Cisco products,
obtaining assistance with security incidents, and registering to receive
security information from Cisco, is available on Cisco's worldwide website at 
http://www.cisco.com/en/US/products/products_security_vulnerability_policy.html
. This includes instructions for press inquiries regarding Cisco security
notices. All Cisco security advisories are available at http://www.cisco.com/go
/psirt.

- -------------------------------------------------------------------------------

All contents are Copyright © 1992-2004 Cisco Systems, Inc. All rights reserved.
Important Notices and Privacy Statement.

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