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Cisco Security Advisory: Cisco IOS Software Network Time Protocol
Packet Vulnerability

Advisory ID: cisco-sa-20090923-ntp

Revision 1.0

For Public Release 2009 September 23

+---------------------------------------------------------------------

Summary
======
Cisco IOS=AE Software with support for Network Time Protocol (NTP)
version (v4) contains a vulnerability processing specific NTP packets
that will result in a reload of the device. This results in a remote
denial of service (DoS) condition on the affected device.

Cisco has released free software updates that address this
vulnerability.

Workarounds that mitigate this vulnerability are available.

This advisory is posted at:

http://www.cisco.com/warp/public/707/cisco-sa-20090923-ntp.shtml 

Note: The September 23, 2009, Cisco IOS Security Advisory bundled
publication includes eleven Security Advisories. Ten of the
advisories address vulnerabilities in Cisco IOS Software, and one
advisory addresses a vulnerability in Cisco Unified Communications
Manager. Each advisory lists the releases that correct the
vulnerability or vulnerabilities detailed in the advisory. The
following table lists releases that correct all Cisco IOS Software
vulnerabilities that have been published on September 23, 2009, or
earlier.

http://www.cisco.com/warp/public/707/cisco-sa-20090923-bundle.shtml 

Individual publication links are in "Cisco Event Response: Semiannual
Cisco IOS Software Advisory Bundled Publication" at the following
link:

http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_sep09.html 

Affected Products
================
Vulnerable Products
+------------------

Cisco IOS Software devices are vulnerable if they support NTPv4 and
are configured for NTP operations. NTP is not enabled in Cisco IOS
Software by default.

To see if a device supports NTPv4, log into the device and via
configuration mode of the command line interface (CLI), enter the
command "ntp peer 127.0.0.1 version ?". If the output has the number "4"
as an option, then the device supports NTPv4. The following example
identifies a Cisco device that is running a Cisco IOS Software
release that does support NTPv4:

    Router#configure terminal
    Router(config)#ntp peer 127.0.0.1 version ?
      <2-4>  NTP version number

The following example identifies a Cisco device that is running a
Cisco IOS Software release that does not support NTPv4:

    Router(config)#ntp peer 127.0.0.1 version ?
      <1-3>  NTP version number

To see if a device is configured with NTP, log into the device and
issue the CLI command "show running-config | include ntp". If the
output returns either of the following commands listed then the
device is vulnerable:

    ntp master 
    ntp peer 
    ntp server 
    ntp broadcast client
    ntp multicast client

The following example identifies a Cisco device that is configured
with NTP:

    router#show running-config | include ntp
    ntp peer 192.168.0.12

The following example identifies a Cisco device that is not
configured with NTP:

    router#show running-config | include ntp
    router#

To determine the Cisco IOS Software release that is running on a
Cisco product, administrators can log in to the device and issue the 
"show version" command to display the system banner. The system banner
confirms that the device is running Cisco IOS Software by displaying
text similar to "Cisco Internetwork Operating System Software" or
"Cisco IOS Software." The image name displays in parentheses,
followed by "Version" and the Cisco IOS Software release name. Other
Cisco devices do not have the "show version" command or may provide
different output.

The following example identifies a Cisco product that is running
Cisco IOS Software Release 12.3(26) with an installed image name of
C2500-IS-L:

    Router#show version
     Cisco Internetwork Operating System Software
     IOS (tm) 2500 Software (C2500-IS-L), Version 12.3(26), RELEASE SOFTWARE (fc2)
Technical Support: http://www.cisco.com/techsupport 
     Copyright =A9) 1986-2008 by cisco Systems, Inc.
     Compiled Mon 17-Mar-08 14:39 by dchih
    
     


The following example shows a product that is running Cisco IOS
Software release 12.4(20)T with an image name of
C1841-ADVENTERPRISEK9-M:

    Router#show version
    Cisco IOS Software, 1841 Software (C1841-ADVENTERPRISEK9-M), Version 12.4(20)T, RELEASE SOFTWARE (fc3)
Technical Support: http://www.cisco.com/techsupport 
    Copyright =A9) 1986-2008 by Cisco Systems, Inc.
    Compiled Thu 10-Jul-08 20:25 by prod_rel_team
    
    


Additional information about Cisco IOS Software release naming
conventions is available in "White Paper: Cisco IOS Reference Guide"
at the following link:

http://www.cisco.com/warp/public/620/1.html 

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

The following products and features are not affected by this
vulnerability:

  * Cisco IOS Software devices without support for NTPv4
  * Cisco IOS Software devices configured with only Simple NTP (SNTP)
    feature
  * Cisco IOS XE Software
  * Cisco IOS XR Software

No other Cisco products are currently known to be affected by this
vulnerability.

Details
======
The Network Time Protocol (NTP) is a protocol designed to
time-synchronize a network of machines. NTP runs over UDP, which in
turn runs over IP. NTPv3 is documented in RFC1305 leavingcisco.com .
NTPv4 is a significant revision of the NTP standard, and is the
current development version, but has not been formalized into an RFC
at the time of publication of this advisory. NTPv4 is currently
documented in draft-ietf-ntp-ntpv4-proto-11 leavingcisco.com

When a Cisco IOS Software device supporting NTPv4 receives a specific
NTP packet it will crash while creating the NTP reply packet. The NTP
packet can be sent from any remote device, and does not require
authentication. Cisco IOS devices supporting NTPv4 and configured
with NTP peer authentication are still vulnerable. The device does
not have to be explicitly configured for NTPv4 peers. For example a
device configured with all NTP peers being explicitly labeled as
version 2 would still be vulnerable, as shown in the following
example:

    Router#show running-config | include ntp
    ntp peer 192.168.0.254 version 2
    ntp peer 192.168.0.1 version 2
    Router#

For further information on the Cisco implementation of NTP, consult
the configuration guide "Cisco IOS and NX-OS Software - Performing
Basic System Management" at the following link:

http://www.cisco.com/en/US/docs/ios/netmgmt/configuration/guide/nm_basic_sys_manage.html#wp1001170 

This vulnerability is documented in the following Cisco Bug IDs: 
CSCsu24505 and CSCsv75948 and has been assigned the Common Vulnerabilities
and Exposures (CVE) identifier CVE-2009-2869. Both Cisco bug IDs are
required for a full fix to this vulnerability.

Vulnerability Scoring Details
============================
Cisco has provided scores for the vulnerability in this advisory
based on the Common Vulnerability Scoring System (CVSS). The CVSS
scoring in this Security Advisory is done in accordance with CVSS
version 2.0.

CVSS is a standards-based scoring method that conveys vulnerability
severity and helps determine urgency and priority of response.

Cisco has provided a base and temporal score. Customers can then
compute environmental scores to assist in determining the impact of
the vulnerability in individual networks.

Cisco has provided an FAQ to answer additional questions regarding
CVSS at:

http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html 

Cisco has also provided a CVSS calculator to help compute the
environmental impact for individual networks at:

http://intellishield.cisco.com/security/alertmanager/cvss 

CSCsu24505, CSCsv75948 - Cisco IOS Software NTP Packet Vulnerability

CVSS Base Score - 7.8

Access Vector           - Network
Access Complexity       - Low
Authentication          - None
Confidentiality Impact  - None
Integrity Impact        - None
Availability Impact     - Complete

CVSS Temporal Score - 6.4

Exploitability          - Functional
Remediation Level       - Official-Fix
Report Confidence       - Confirmed

Impact
=====
Successful exploitation of the vulnerability may result in a reload
of the device. The vulnerability could be repeatedly exploited to
cause an extended DoS condition.

Software Versions and Fixes
==========================
When considering software upgrades, also consult:

http://www.cisco.com/go/psirt 

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) or your contracted
maintenance provider for assistance.

Each row of the Cisco IOS software table (below) names a Cisco IOS
release train. If a given release train is vulnerable, then the
earliest possible releases that contain the fix (along with the
anticipated date of availability for each, if applicable) are listed
in the "First Fixed Release" column of the table. The "Recommended
Release" column indicates the releases which have fixes for all the
published vulnerabilities at the time of this Advisory. A device
running a release in the given train that is earlier than the release
in a specific column (less than the First Fixed Release) is known to
be vulnerable. Cisco recommends upgrading to a release equal to or
later than the release in the "Recommended Releases" column of the
table.

+-------------------------------------------------------------------+
|   Major    |          Availability of Repaired Releases           |
|  Release   |                                                      |
|------------+------------------------------------------------------|
|  Affected  |                                       | Recommended  |
| 12.0-Based |          First Fixed Release          |   Release    |
|  Releases  |                                       |              |
|-------------------------------------------------------------------|
| There are no affected 12.0 based releases                         |
|-------------------------------------------------------------------|
|  Affected  |                                       | Recommended  |
| 12.1-Based |          First Fixed Release          |   Release    |
|  Releases  |                                       |              |
|-------------------------------------------------------------------|
| There are no affected 12.1 based releases                         |
|-------------------------------------------------------------------|
|  Affected  |                                       | Recommended  |
| 12.2-Based |          First Fixed Release          |   Release    |
|  Releases  |                                       |              |
|-------------------------------------------------------------------|
| There are no affected 12.2 based releases                         |
|-------------------------------------------------------------------|
|  Affected  |                                       | Recommended  |
| 12.3-Based |          First Fixed Release          |   Release    |
|  Releases  |                                       |              |
|-------------------------------------------------------------------|
| There are no affected 12.3 based releases                         |
|-------------------------------------------------------------------|
|  Affected  |                                       | Recommended  |
| 12.4-Based |          First Fixed Release          |   Release    |
|  Releases  |                                       |              |
|------------+---------------------------------------+--------------|
| 12.4       | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4GC     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4JA     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4JDA    | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4JDC    | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4JDD    | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4JK     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4JL     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4JMA    | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4JMB    | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4JX     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
|            | Releases prior to 12.4(22)MD are not  |              |
| 12.4MD     | vulnerable, vulnerability was first   | 12.4(22)MD1  |
|            | introduced in 12.4(22)MD, first fixed |              |
|            | in 12.4(22)MD1.                       |              |
|------------+---------------------------------------+--------------|
| 12.4MDA    | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4MR     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4SW     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
|            | Releases prior to 12.4(20)T are not   |              |
|            | vulnerable.                           |              |
|            |                                       | 12.4(20)T4   |
|            | 12.4(20)T and 12.4(20)T1 are          |              |
|            | vulnerable, vulnerability is first    | 12.4(22)T3   |
| 12.4T      | fixed in 12.4(20)T2.                  |              |
|            |                                       | 12.4(24)T2;  |
|            | 12.4(22)T is vulnerable,              | Available on |
|            | vulnerability is first fixed in 12.4  | 23-OCT-2009  |
|            | (22)T1                                |              |
|            |                                       |              |
|            | 12.4(24)T is not vulnerable.          |              |
|------------+---------------------------------------+--------------|
| 12.4XA     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XB     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XC     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XD     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XE     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XF     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XG     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XJ     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XK     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XL     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XM     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XN     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XP     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XQ     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XR     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XT     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XV     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XW     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4XY     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
|            |                                       | 12.4(20)T4   |
|            |                                       |              |
|            |                                       | 12.4(22)T3   |
| 12.4XZ     | Vulnerable; first fixed in 12.4T      |              |
|            |                                       | 12.4(24)T2;  |
|            |                                       | Available on |
|            |                                       | 23-OCT-2009  |
|------------+---------------------------------------+--------------|
|            |                                       | 12.4(20)T4   |
|            |                                       |              |
|            |                                       | 12.4(22)T3   |
| 12.4YA     | Vulnerable; first fixed in 12.4T      |              |
|            |                                       | 12.4(24)T2;  |
|            |                                       | Available on |
|            |                                       | 23-OCT-2009  |
|------------+---------------------------------------+--------------|
| 12.4YB     | Not Vulnerable                        |              |
|------------+---------------------------------------+--------------|
| 12.4YD     | 12.4(22)YD1                           | 12.4(22)YD1  |
|------------+---------------------------------------+--------------|
| 12.4YE     | 12.4(22)YE1                           | 12.4(22)YE1  |
+-------------------------------------------------------------------+

Workarounds
==========
There are no workarounds other than disabling NTP on the device. The
following mitigations have been identified for this vulnerability;
only packets destined for any configured IP address on the device can
exploit this vulnerability. Transit traffic will not exploit this
vulnerability.

Note: NTP peer authentication is not a workaround and is still a
vulnerable configuration.

NTP Access Group
+---------------

Warning: Because the feature in this vulnerability utilizes
UDP as a transport, it is possible to spoof the sender's IP address,
which may defeat access control lists (ACLs) that permit
communication to these ports from trusted IP addresses. Unicast
Reverse Path Forwarding (Unicast RPF) should be considered to be used
in conjunction to offer a better mitigation solution.

    
    !--- Configure trusted peers for allowed access
    
    
    access-list 1 permit 171.70.173.55
    
    
    !--- Apply ACE to the NTP configuration
    
    
    ntp access-group 1

For additional information on NTP access control groups, consult the
document titled "Performing Basic System Management" at the following
link:

http://www.cisco.com/en/US/docs/ios/netmgmt/configuration/guide/nm_basic_sys_manage.html#wp1034942 

Infrastructure Access Control Lists
+----------------------------------

warning Warning: Because the feature in this vulnerability utilizes
UDP as a transport, it is possible to spoof the sender's IP address,
which may defeat ACLs that permit communication to these ports from
trusted IP addresses. Unicast RPF should be considered to be used in
conjunction to offer a better mitigation solution.

Although it is often difficult to block traffic that transits a
network, it is possible to identify traffic that should never be
allowed to target infrastructure devices and block that traffic at
the border of networks. Infrastructure ACLs (iACLs) are a network
security best practice and should be considered as a long-term
addition to good network security as well as a workaround for this
specific vulnerability. The iACL example below should be included as
part of the deployed infrastructure access-list, which will help
protect all devices with IP addresses in the infrastructure IP
address range:

    
    !---
    !--- Feature: Network Time Protocol (NTP)
    !---
    
    
    access-list 150 permit udp TRUSTED_SOURCE_ADDRESSES WILDCARD 
        INFRASTRUCTURE_ADDRESSES WILDCARD eq 123
    
    
    !--- Note: If the router is acting as a NTP broadcast client
    !---   via the interface command "ntp broadcast client"
    !---   then broadcast and directed broadcasts must be 
    !---   filtered as well.  The following example covers
    !---   an infrastructure address space of 192.168.0.X
    
    
    access-list 150 permit udp TRUSTED_SOURCE_ADDRESSES WILDCARD 
        host 192.168.0.255 eq ntp
    access-list 150 permit udp TRUSTED_SOURCE_ADDRESSES WILDCARD 
        host 255.255.255.255 eq ntp
    
    
    !--- Note: If the router is acting as a NTP multicast client
    !---   via the interface command "ntp multicast client"
    !---   then multicast IP packets to the mutlicast group must
    !---   be filtered as well.  The following example covers
    !---   a NTP multicast group of 239.0.0.1 (Default is
    !---   224.0.1.1)
    
    
    access-list 150 permit udp TRUSTED_SOURCE_ADDRESSES WILDCARD 
        host 239.0.0.1 eq ntp
    
    
    !--- Deny NTP traffic from all other sources destined
    !--- to infrastructure addresses.
    
    
    access-list 150 deny udp any 
        INFRASTRUCTURE_ADDRESSES WILDCARD eq 123
    
    
    !--- Permit/deny all other Layer 3 and Layer 4 traffic in
    !--- accordance with existing security policies and
    !--- configurations.  Permit all other traffic to transit the
    !--- device.
    
    
    access-list 150 permit ip any any
    
    
    !--- Apply access-list to all interfaces (only one example
    !--- shown)
     
    
    interface fastEthernet 2/0
     ip access-group 150 in

The white paper entitled "Protecting Your Core: Infrastructure
Protection Access Control Lists" presents guidelines and recommended
deployment techniques for infrastructure protection access lists and
is available at the following link:

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801a1a55.shtml 

Control Plane Policing
+---------------------

Warning: Because the feature in this vulnerability utilizes UDP as a
transport, it is possible to spoof the sender's IP address, which may
defeat ACLs that permit communication to these ports from trusted IP
addresses. Unicast RPF should be considered to be used in conjunction
to offer a better mitigation solution.

Control Plane Policing (CoPP) can be used to block untrusted UDP
traffic to the device. Cisco IOS software releases 12.0S, 12.2SX,
12.2S, 12.3T, 12.4, and 12.4T support the CoPP feature. CoPP can be
configured on a device to help protect the management and control
planes and minimize the risk and effectiveness of direct
infrastructure attacks by explicitly permitting only authorized
traffic that is sent to infrastructure devices in accordance with
existing security policies and configurations. The CoPP example below
should be included as part of the deployed CoPP, which will help
protect all devices with IP addresses in the infrastructure IP
address range.

    
    !--- Feature: Network Time Protocol (NTP)
    
    
    access-list 150 deny udp TRUSTED_SOURCE_ADDRESSES WILDCARD
         any eq 123
    
    
    !--- Deny NTP traffic from all other sources destined
    !--- to the device control plane.
    
    
    access-list 150 permit udp any any eq 123
    
    
    !--- Permit (Police or Drop)/Deny (Allow) all other Layer3 and 
    !--- Layer4 traffic in accordance with existing security policies
    !--- and configurations for traffic that is authorized to be sent
    !--- to infrastructure devices
    !--- Create a Class-Map for traffic to be policed by
    !--- the CoPP feature
    
    
    class-map match-all drop-udp-class
     match access-group 150
    
    
    !--- Create a Policy-Map that will be applied to the
    !--- Control-Plane of the device.
    
    
    policy-map drop-udp-traffic
     class drop-udp-class
      drop
    
    
    !--- Apply the Policy-Map to the 
    !--- Control-Plane of the device
    
    
    control-plane
     service-policy input drop-udp-traffic

In the above CoPP example, the access control list entries (ACEs)
that match the potential exploit packets with the "permit" action
result in these packets being discarded by the policy-map "drop"
function, while packets that match the "deny" action (not shown) are
not affected by the policy-map drop function. Please note that the
policy-map syntax is different in the 12.2S and 12.0S Cisco IOS
Software trains:

    policy-map drop-udp-traffic
    class drop-udp-class
    police 32000 1500 1500 conform-action drop exceed-action drop

Additional information on the configuration and use of the CoPP
feature can be found in the documents, "Control Plane Policing
Implementation Best Practices" and "Cisco IOS Software Releases 12.2
S - Control Plane Policing" at the following links:

http://www.cisco.com/web/about/security/intelligence/coppwp_gs.html 

and

http://www.cisco.com/en/US/docs/ios/12_3t/12_3t4/feature/guide/gtrtlimt.html 

Obtaining Fixed Software
=======================
Cisco has released free software updates that address these
vulnerabilities. Prior to deploying software, customers should
consult their maintenance provider or check the software for feature
set compatibility and known issues specific to their environment.

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/en/US/docs/general/warranty/English/EU1KEN_.html 

or as otherwise set forth at Cisco.com Downloads at:

http://www.cisco.com/public/sw-center/sw-usingswc.shtml 

Do not contact psirt@cisco.com or security-alert@cisco.com for 
software upgrades.

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 agreements with third-party support organizations,
such as Cisco Partners, authorized resellers, or service providers
should contact that support organization for guidance and assistance
with the appropriate course of action in regards to this advisory.

The effectiveness of any workaround or fix 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 or
fix is the most appropriate for use in the intended network before it
is deployed.

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

Customers who purchase direct from Cisco but do not hold a Cisco
service contract, and customers who purchase through third-party
vendors but are unsuccessful in obtaining fixed software through
their point of sale should acquire 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 

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

Refer to:

http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html 

for additional TAC contact information, including localized telephone
numbers, and instructions and e-mail addresses for use in various
languages.

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

This vulnerability was discovered by Cisco when handling customer
support calls.

Status of this Notice: FINAL
===========================
THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY
KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE
INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS
AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS
DOCUMENT AT ANY TIME.

A stand-alone copy or Paraphrase of the text of this document 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 is posted on Cisco's worldwide website at:

http://www.cisco.com/warp/public/707/cisco-sa-20090923-ntp.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-bulletins@lists.first.org 
* bugtraq@securityfocus.com 
* vulnwatch@vulnwatch.org 
* cisco@spot.colorado.edu 
* cisco-nsp@puck.nether.net 
* full-disclosure@lists.grok.org.uk 
* 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 |                   | Initial |
| 1.0      | 2009-September-23 | public  |
|          |                   | 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 
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