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Cisco Security Advisory: Cisco IOS XR MPLS Vulnerabilities
From: Cisco Systems Product Security Incident Response Team <psirt () cisco com>
Date: Wed, 19 Apr 2006 17:00:00 +0200

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Cisco Security Advisory: Cisco IOS XR MPLS Vulnerabilities

Advisory ID: cisco-sa-20060419-xr

http://www.cisco.com/warp/public/707/cisco-sa-20060419-xr.shtml

Revision 1.0

For Public Release 2006 April 19 1500 UTC (GMT)

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

Contents
========

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

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

Summary
=======

Multiple Multi Protocol Label Switching (MPLS) related
vulnerabilities exist on Cisco IOS  XR. Only systems that are running
Cisco IOS XR and configured for MPLS are affected by these
vulnerabilities.

Upon successful exploitation a Modular Services Card (MSC) on a Cisco
Carrier Routing System 1 (CRS-1) or a Line Card (LC) on a Cisco 12000
series router may reload affecting switched traffic.

Cisco has made free software available to address this vulnerability
for affected customers.

This advisory is posted at 
http://www.cisco.com/warp/public/707/cisco-sa-20060419-xr.shtml.

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

Vulnerable Products
+------------------

Only systems that are running Cisco IOS XR and configured for MPLS
are affected by this vulnerability.

Systems that are running Cisco IOS XR and configured for MPLS can be
identified by the show mpls interfaces command. A sample output of
this command on a CRS-1 that is configured for MPLS is given below.

      RP/0/RP1/CPU0:crs1#show mpls interfaces
      Interface                  LDP      Tunnel   Enabled
      -------------------------- -------- -------- --------
      POS0/2/0/0                 Yes      Yes      Yes
      POS0/2/0/1                 No       Yes      Yes
      POS0/2/0/2                 Yes      No       Yes
      POS0/2/0/3                 Yes      Yes      Yes
      GigabitEthernet0/3/1/0     Yes      No       Yes
      GigabitEthernet0/3/1/3     Yes      No       Yes
      POS0/3/0/1                 Yes      Yes      Yes
      TenGigE0/6/0/0             Yes      No       Yes
      RP/0/RP1/CPU0:crs#


In the above output, the fourth column labeled Enabled identifies
MPLS enabled interfaces.

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

Cisco IOS XR only runs on CRS-1 or Cisco 12000 series routers. Other
Cisco products, including systems that run Cisco IOS are not
affected.

Details
=======

Cisco IOS XR Software is a member of the Cisco IOS Software Family
that uses a microkernel based distributed operating system
infrastructure. Cisco IOS XR runs both on Cisco CRS-1 and Cisco 12000
series routers.

More information on Cisco IOS XR can be found at the following URL:

http://www.cisco.com/en/US/products/ps5845/index.html

Modular Services Cards (MSC), also called the line cards are Layer-3
forwarding engines on Cisco CRS-1. An MSC is paired with a physical
layer interface module (PLIM) which provides layer-1 and layer-2
services.

More information on Cisco CRS-1 architecture can be found at the
following URL:

http://www.cisco.com/en/US/products/ps5763/index.html

Specific MPLS packets that are switched by a Cisco CRS-1 or a 12000
series system will restart the NetIO process. If the NetIO process is
restarted several times consecutively, the line card will reload
causing a Denial of Service (DoS) condition for the traffic that is
being switched on that line card.

MPLS packets will be forwarded through the MPLS network. Therefore,
packets that can trigger this vulnerability can be sent from remote
systems that are in the MPLS network. Such packets can not be
received on interfaces that are not configured for MPLS.

This vulnerability is addressed by the following Cisco bug IDs:

  * CSCsd15970 -- MSC crash upon receipt of specific MPLS packets
    This bug only affects CRS-1 and does not affect Cisco 12000
    series routers that are running Cisco IOS XR.

  * CSCsd55531 -- MPLS packet handling problems
    This bug only affects CRS-1 and does not affect Cisco 12000
    series routers that are running Cisco IOS XR.

  * CSCsc77475 -- Line card crash upon receipt of specific MPLS
    packets
    This bug affects both CRS-1 and Cisco 12000 series routers that
    are running Cisco IOS XR.


Impact
======

Successful exploitation of the vulnerability may result in a reload
of the Modular Services Card (MSC) on a CRS-1 or the line cards on a
Cisco 12000 series router. Repeated exploitation could result in a
sustained DoS attack.

Software Version 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.

+---------------------------------------+
| Cisco IOS XR  | SMU ID                |
| Version       |                       |
|---------------+-----------------------|
| 3.2.0         | AA01447               |
|---------------+-----------------------|
| 3.2.1         | AA01446               |
|---------------+-----------------------|
| 3.2.2         | AA01448               |
|---------------+-----------------------|
| 3.2.3 for     | AA01444               |
| CRS-1         |                       |
|---------------+-----------------------|
| 3.2.3 for PRP | AA01451               |
|---------------+-----------------------|
| 3.2.4         | AA01449               |
|---------------+-----------------------|
| 3.2.50        | AA01450               |
|---------------+-----------------------|
| 3.3           | Cisco IOS XR 3.3 is   |
|               | not vulnerable        |
+---------------------------------------+

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

There is no workaround to mitigate the effects of these
vulnerabilities.

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

Cisco will make free software available to address this vulnerability
for affected customers. This advisory will be updated as fixed
software becomes available. 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/public/sw-license-agreement.html , or as otherwise 
set forth at Cisco.com Downloads at 
http://www.cisco.com/public/sw-center/sw-usingswc.shtml.

Do not contact either "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 agreement 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 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

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.

Refer to 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.

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 reported to Cisco by a customer.

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-20060419-xr.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
  * 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      | 2006-April-19 | 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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