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Cisco Security Advisory: Cisco IOS Software Processing of SAA Packets
From: Cisco Systems Product Security Incident Response Team <psirt () cisco com>
Date: Thu, 15 May 2003 19:04:43 +0100 (BST)


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Cisco Security Advisory: Cisco IOS Software Processing of SAA Packets

Revision 1.0

For Public Release 2003 May 15 15:00 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
=======
The Service Assurance Agent (SAA) is the new name for the Response Time
Reporter (RTR) feature.

The router is vulnerable only if the RTR responder is enabled. When the
router receives a malformed RTR packet, it will crash. RTR is disabled by
default. Although RTR was introduced in Cisco IOSĀ® Software Release 11.2,
only the following main releases are vulnerable:

  * 12.0S, SC, ST, SL, SP, SX
   
  * 12.1, E, EA, EC, EX, EY
   
  * 12.2, DA, S
   
For the complete list please see the Software Versions and Fixes section.

No other Cisco product is vulnerable.

There is no workaround short of disabling the RTR responder. It is
possible to mitigate the vulnerability by applying the access control
list (ACL) on the router.

This advisory is available at http://www.cisco.com/warp/public/707/
cisco-sa-20030515-saa.shtml.

Affected Products
=================
This vulnerability affects the following main Cisco IOS Software releases
(some X releases are also affected, and those details are in the Software
Version and Fixes section).

+-----------------------------------------+
|  Major  |      Vulnerable Releases      |
| Release |                               |
|---------+-------------------------------|
| 12.0S   | 15, 16, 17, 18, 19, 21        |
|---------+-------------------------------|
| 12.0SC  | 15, 16                        |
|---------+-------------------------------|
| 12.0SL  | 15, 17, 19                    |
|---------+-------------------------------|
| 12.0ST  | 16, 17, 18, 19, 20, 21        |
|---------+-------------------------------|
| 12.0SP  | 19, 20                        |
|---------+-------------------------------|
| 12.0SX  | 21                            |
|---------+-------------------------------|
| 12.1    | 10, 10a, 11, 11a, 11b, 12,    |
|         | 12a, 12b, 12c, 13, 14, 14.5   |
|---------+-------------------------------|
| 12.1E   | 10, 11b, 11.5                 |
|---------+-------------------------------|
| 12.1EA  | 8, 9                          |
|---------+-------------------------------|
| 12.1EC  | 10, 10.5                      |
|---------+-------------------------------|
| 12.1EX  | 10                            |
|---------+-------------------------------|
| 12.1EY  | 10                            |
|---------+-------------------------------|
| 12.2    | 6.8a, 7, 7a, 7b, 7c           |
|---------+-------------------------------|
| 12.2DA  | 7, 9.4                        |
|---------+-------------------------------|
| 12.2S   | 9, 10.5                       |
+-----------------------------------------+

No other Cisco products are affected.

Details
=======
The RTR feature allows you to monitor network performance, network
resources, and applications by measuring response times and availability.
With this feature you can perform troubleshooting, problem notifications,
and problem analysis based on response time reporter statistics.

A router is vulnerable only if the RTR responder is enabled. In order to
verify this, check the router's configuration. Execute the following
command while logged on a router:

    Router>show rtr responder
         RTR Responder is: Enabled
         Number of control messages received: 0 Number of errors: 0 
         Recent sources:
         Recent error sources:

If you notice the line "RTR Responder is: Enabled," then you are
vulnerable.

Alternatively, you can use this procedure:

    Router>show ip socket
         show ip socket
         Proto    Remote      Port      Local       Port  In Out Stat TTY
OutputIF
         ....
          17 0.0.0.0             0 10.0.0.1         1967   0   0   89   0

If you notice a line as in the example above where the router is
listening to the port 1967, then you are vulnerable.

For Cisco IOS Software, this vulnerability is documented as two Cisco Bug
IDs: CSCdx17916 and CSCdx61997.

Impact
======
By sending malformed RTR packets, it is possible to crash the router.

Software Versions and Fixes
===========================
Each row of the Cisco IOS software table (below) describes a release
train and the platforms or products for which it is intended. If a given
release train is vulnerable, then the earliest possible releases that
contain the fix (the "First Fixed Release") and the anticipated date of
availability for each are listed in the "Rebuild," "Interim," and
"Maintenance" columns. 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. The release should be upgraded
at least to the indicated release or a later version (greater than or
equal to the First Fixed Release label). When selecting a release, keep
in mind the following definitions.

  * Maintenance - The most heavily tested, stable, and highly recommended
    release of a release train in any given row of the table.
   
  * Rebuild - Constructed from the previous maintenance or major release
    in the same train, it contains the fix for a specific defect.
    Although it receives less testing, it contains only the minimal
    changes necessary to repair the vulnerability.
   
  * Interim - Built at regular intervals between maintenance releases and
    receives less testing. Interims should be selected only if there is
    no other suitable release that addresses the vulnerability. Interim
    images should be upgraded to the next available maintenance release
    as soon as possible. Interim releases are not available through
    manufacturing, and usually they are not available for customer
    download from http://www.cisco.com without prior arrangement with the
    Cisco TAC.
   
In all cases, customers should exercise caution to confirm that the
devices to be upgraded contain sufficient memory and that current
hardware and software configurations will continue to be supported
properly by the new software release. If the information is not clear,
contact the Cisco TAC for assistance as shown in the Obtaining Fixed
Software section below.

More information on Cisco IOS software release names and abbreviations is
available at http://www.cisco.com/warp/public/620/1.html.

The fixes will be available at the Software Center located at http://
www.cisco.com/tacpage/sw-center/.

+-------------------------------------------------------------------------+
|  Major   | Description |         Availability of Repaired Releases*     |
| Release  | or Platform |                                                |
|------------------------+------------------------------------------------|
|    Affected Earlier    |  Rebuild   |     Interim**   |   Maintenance   |
|        Releases        |            |                 |                 |
|------------------------+------------------------------------------------|
| 11.1 and |             |                                                |
| earlier, | Numerous    | Not vulnerable                                 |
| all      |             |                                                |
| variants |             |                                                |
|------------------------+------------------------------------------------|
|  Affected 11.2-Based   |  Rebuild   |     Interim**   |   Maintenance   |
|        Releases        |            |                 |                 |
|------------------------+------------------------------------------------|
| 11.2     | Numerous    | Not vulnerable                                 |
| variants |             |                                                |
|------------------------+------------------------------------------------|
|  Affected 11.3-Based   |  Rebuild   |     Interim**   |   Maintenance   |
|        Releases        |            |                 |                 |
|------------------------+------------------------------------------------|
| 11.3     | Numerous    | Not vulnerable                                 |
| variants |             |                                                |
|------------------------+------------------------------------------------|
|  Affected 12.0-Based   |  Rebuild   |     Interim**   |   Maintenance   |
|        Releases        |            |                 |                 |
|------------------------+------------+-----------------+-----------------|
|          | Core/ISP    |            |                 |                 |
|          | Support:    |            |                 |                 |
| 12.0S    | GSR, RSP,   | 12.0(21)S3 | 12.0(21.03)S    |                 |
|          | c7200,      |            |                 |                 |
|          | Cat6000     |            |                 |                 |
|----------+-------------+------------------------------------------------|
|          | Cable/      | Not planned                                    |
| 12.0SC   | Broadband   |                                                |
|          | ISP:        | Migrate to 12.1EC release                      |
|          | ubr7200     |                                                |
|----------+-------------+------------------------------------------------|
|          | 10000 ESR:  | If using Pre1 card, then migrate to 12.0ST or  |
| 12.0SL   | c10k        | 12.0S                                          |
|          |             | For Pre card the date is not yet determined.   |
|----------+-------------+------------------------------------------------|
| 12.0SP   | c10720      | 12.0(20)SP3| 12.0(20.04)SP2  |                 |
|----------+-------------+------------+-----------------+-----------------|
|          | MPLS/Tag    | 12.0(19)ST5|                 |                 |
| 12.0ST   | Switching,  |            |                 |                 |
|          | GSR 12000,  | 12.0(21)ST2|                 |                 |
|          | 7200, 7500  |            |                 |                 |
|----------+-------------+------------------------------------------------|
|          | Short-lived |                                                |
|          | early       |                                                |
| 12.0SX   | deployment  | To be determined                               |
|          | release     |                                                |
|          | 10000 ESR:  |                                                |
|          | c10k        |                                                |
|----------+-------------+------------------------------------------------|
| 12.0SY   |             |            | 12.0(21.03)SY   | 12.0(22)SY      |
|----------+-------------+------------+-----------------+-----------------|
|          | Short-lived |            |                 |                 |
|          | early       |            |                 |                 |
| 12.0WC   | deployment  | 12.0(5)WCa |                 |                 |
|          | release for |            |                 |                 |
|          | 2900XL and  |            |                 |                 |
|          | 3500XL      |            |                 |                 |
|----------+-------------+------------------------------------------------|
|          | Short-lived | Not planned                                    |
| 12.0XE   | early       |                                                |
|          | deployment  | Migrate to 12.2 release or later               |
|          | release     |                                                |
|------------------------+------------------------------------------------|
|  Affected 12.1-Based   |  Rebuild   |     Interim**   |   Maintenance   |
|        Releases        |            |                 |                 |
|------------------------+------------+-----------------+-----------------|
|          | General     |            |                 |                 |
|          | Deployment  |            |                 |                 |
| 12.1     | (GD)        |            | 12.1(18.1)      | 12.1(18)        |
|          | candidate:  |            |                 |                 |
|          | all         |            |                 |                 |
|          | platforms   |            |                 |                 |
|----------+-------------+------------+-----------------+-----------------|
|          | Core/ISP    |            |                 |                 |
| 12.1E    | Support:    |            | 12.1(12.5)E     | 12.1(13)E       |
|          | GSR, RSP,   |            |                 |                 |
|          | c7200       |            |                 |                 |
|----------+-------------+------------+-----------------+-----------------|
| 12.1EA   | Catalyst    | 12.1(8)EA1c|                 |                 |
|          | 2950        |            |                 |                 |
|----------+-------------+------------+-----------------+-----------------|
|          | Early       |            |                 |                 |
|          | Deployment  |            |                 |                 |
| 12.1EC   | (ED):       |            | 12.1(12c)EC     |                 |
|          | ubr7200,    |            |                 |                 |
|          | UBR Headend |            |                 |                 |
|          | platforms   |            |                 |                 |
|----------+-------------+------------+-----------------+-----------------|
|          | Early       |            |                 |                 |
|          | Deployment  |            |                 |                 |
| 12.1EW   | release,    |            |                 | 12.1(11b)EW     |
|          | limited     |            |                 |                 |
|          | platforms   |            |                 |                 |
|----------+-------------+------------+-----------------+-----------------|
|          | Early       |            |                 |                 |
|          | Deployment  |            |                 |                 |
| 12.1EW   | release,    |            |                 |12.1(11b)EW(0.46)|
|          | limited     |            |                 |                 |
|          | platforms   |            |                 |                 |
|----------+-------------+------------+-----------------+-----------------|
| 12.1EX   | Catalyst    |            |                 | 12.1(11b)EX     |
|          | 6000        |            |                 |                 |
|----------+-------------+------------------------------------------------|
|          | Short-lived |                                                |
| 12.1XF   | early       | Not planned Migrate to 12.1(5)T or later       |
|          | deployment  |                                                |
|          | release     |                                                |
|----------+-------------+------------------------------------------------|
|          | Short-lived |                                                |
| 12.1XG   | early       | Not planned Migrate to 12.1(1)T or later       |
|          | deployment  |                                                |
|          | release     |                                                |
|----------+-------------+------------------------------------------------|
|          | Short-lived |                                                |
| 12.1YB   | early       | Not planned Migrate to 12.1(2)T or later       |
|          | deployment  |                                                |
|          | release     |                                                |
|----------+-------------+------------------------------------------------|
|          | Short-lived |                                                |
| 12.1YC   | early       | Not planned Migrate to 12.1(4)T or later       |
|          | deployment  |                                                |
|          | release     |                                                |
|------------------------+------------------------------------------------|
|  Affected 12.2-Based   |  Rebuild   |     Interim**   |   Maintenance   |
|        Releases        |            |                 |                 |
|------------------------+------------+-----------------+-----------------|
|          | General     |            |                 |                 |
|          | Deployment  |            |                 |                 |
| 12.2     | (GD)        |            | 12.2(10.4)      | 12.2(10)        |
|          | candidate:  |            |                 |                 |
|          | all         |            |                 |                 |
|          | platforms   |            |                 |                 |
|----------+-------------+------------+-----------------+-----------------|
|          | Early       |            |                 |                 |
|          | Deployment  |            |                 |                 |
| 12.2(4)B | for 6400,   |            | 12.2(13.3)B     |                 |
|          | 7200 and    |            |                 |                 |
|          | 7400        |            |                 |                 |
|----------+-------------+------------------------------------------------|
|          | Early       |                                                |
|          | Deployment  |                                                |
| 12.2BC   | for uBR7000 | To be determined                               |
|          | and         |                                                |
|          | uBR10000    |                                                |
|----------+-------------+------------------------------------------------|
|          | Early       | Not planned                                    |
| 12.2BY   | Deployment  |                                                |
|          | release     | Migrate to 12.2B releases                      |
|----------+-------------+------------------------------------------------|
|          | Early       |            |                 |                 |
| 12.2BZ   | Deployment  |            |                 | 12.2(15)BZ      |
|          | release     |            |                 |                 |
|----------+-------------+------------+-----------------+-----------------|
|          | Early       |            |                 |                 |
|          | deployment  |            |                 |                 |
| 12.2DA   | release     |            | 12.2(11.4)DA    | 12.2(12)DA      |
|          | xDSL        |            |                 |                 |
|          | support:    |            |                 |                 |
|          | 6100, 6200  |            |                 |                 |
|----------+-------------+------------+-----------------+-----------------|
|          | Early       |            |                 |                 |
|          | deployment  |            |                 |                 |
| 12.2MB   | release for | 12.2(4)MB5 |                 |                 |
|          | 2600 and    |            |                 |                 |
|          | 7500        |            |                 |                 |
|----------+-------------+------------+-----------------+-----------------|
| 12.2S    | Core ISP    |            | 12.2(11.1)S     |                 |
|          | support     |            |                 |                 |
|----------+-------------+------------+-----------------+-----------------|
|          | Early       |            |                 |                 |
| 12.2XC   | deployment  | 12.2(1a)XC5|                 |                 |
|          | release     |            |                 |                 |
|----------+-------------+------------------------------------------------|
|          | ICS7750/820 | Not planned                                    |
| 12.2XD   | /soho70     |                                                |
|          |             | Migrate to 12.2(8)YN or later                  |
|----------+-------------+------------------------------------------------|
|          | 806, 828,   | Not planned                                    |
| 12.2XE   | soho78      |                                                |
|          |             | Migrate to 12.2(8)T or later                   |
|----------+-------------+------------------------------------------------|
|          | 1700 820/   | Not planned                                    |
| 12.2XH   | 800/soho70  |                                                |
|          |             | Migrate to 12.2(8)T or later                   |
|----------+-------------+------------------------------------------------|
|          |             | Not planned                                    |
| 12.2XI   | 820/soho    |                                                |
|          |             | Migrate to 12.2(12)T or later                  |
|----------+-------------+------------------------------------------------|
|          |             | Not planned                                    |
| 12.2XJ   | 1700        |                                                |
|          |             | Migrate to 12.2(4)YB or later                  |
|----------+-------------+------------------------------------------------|
| 12.2XK   | 820/soho    |            |                 | 12.2(2)XK3      |
|----------+-------------+------------+-----------------+-----------------|
| 12.2XL   | 1700 820/   |            |                 | 12.2(4)XL5      |
|          | 800/soho70  |            |                 |                 |
|----------+-------------+------------------------------------------------|
|          | Short-lived | Not planned                                    |
| 12.2XM   | early       |                                                |
|          | deployment  | Migrate to 12.2(8)YB or later                  |
|          | release     |                                                |
|----------+-------------+------------------------------------------------|
|          | Short-lived |            |                 |                 |
| 12.2YA   | early       | 12.2(4)YA3 |                 |                 |
|          | deployment  |            |                 |                 |
|          | release     |            |                 |                 |
|----------+-------------+------------------------------------------------|
|          | Short-lived | Not planned                                    |
| 12.2YB   | early       |                                                |
|          | deployment  | Migrate to 12.2(8)YB or later                  |
|          | release     |                                                |
|----------+-------------+------------------------------------------------|
|          | Short-lived |            |                 |                 |
| 12.2YC   | early       | 12.2(4)YC4 |                 |                 |
|          | deployment  |            |                 |                 |
|          | release     |            |                 |                 |
|----------+-------------+------------------------------------------------|
|          | Cisco       |                                                |
|          | Packet Data |                                                |
| 12.2YF   | Serving     | Release date to be decided                     |
|          | Node        |                                                |
|          | ics7700     |                                                |
|----------+-------------+------------------------------------------------|
|          | Short-lived |            |                 |                 |
| 12.2YG   | early       |            |                 | 12.2(4)YG       |
|          | deployment  |            |                 |                 |
|          | release     |            |                 |                 |
|----------+-------------+------------+-----------------+-----------------|
|          | Short-lived |            |                 |                 |
| 12.2YH   | early       |            |                 | 12.2(4)YH       |
|          | deployment  |            |                 |                 |
|          | release     |            |                 |                 |
|-------------------------------------------------------------------------|
|               Notes                                                     |
|-------------------------------------------------------------------------|
| * All dates are estimated and subject to change.                        |
|                                                                         |
| ** Interim releases are subjected to less rigorous testing than regular |
| maintenance releases, and may have serious bugs.                        |
+-------------------------------------------------------------------------+

Obtaining Fixed Software
========================
Cisco is offering free software upgrades to remedy this vulnerability for
all affected customers. 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 the Cisco Connection Online Software Center at
http://www.cisco.com/public/sw-center/sw-usingswc.shtm.

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 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 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). In those cases, customers may only upgrade to a
later version of the same release as indicated by the applicable row in
the Software Versions and Fixes table.

Cisco 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
   
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.

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.

Workarounds
===========
There is no workaround short of disabling the RTR responder. It is
possible to mitigate the vulnerability by applying the ACL on the router.

If you want to disable the RTR, you need to execute the following
commands:

    Router#conf t
    Enter configuration commands, one per line.  End with CNTL/Z.
    Router(config)#no rtr responder
    Router(config)#exit
    Router#copy running-config startup-config

If you want to block all offending packets on your network edge, then you
should create an ACL, or modify an existing one, to contain an entry
resembling:

    Router#conf t
    Enter configuration commands, one per line.  End with CNTL/Z.
    Router(config)#access-list 101 deny udp any any eq 1967
    Router(config)#interface eth0
    Router(config)#ip access-group 101 in

In this example the interface eth0 is assumed to be facing toward the
network edge. You will have to substitute it for the correct interface on
your router.

This will prevent any packet that is destined to the port 1967/UDP from
entering your network. If you need to enable these packets to traverse
your network, then the ACL must exclude only your internal routers.

In addition to filtering packets at the network edge, you may apply
filtering on the device itself and permit packets only from known good
sources. This will contribute to the overall mitigation of this issue.

    Router#conf t
    Enter configuration commands, one per line.  End with CNTL/Z.
    Router(config)#access-list 101 permit udp 10.0.0.1 10.0.0.10 eq 1967
    Router(config)#access-list 101 deny udp any 10.0.0.10 eq 1967
    Router(config)#interface eth0
    Router(config)#ip access-group 101 in

In this example, 10.0.0.1 is the legitimate source and 10.0.0.10 is the
address of the router itself.

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

Status of This Notice: FINAL
============================
This is a final notice. Although Cisco cannot guarantee the accuracy of
all statements in this advisory, all of the facts have been checked to
the best of our ability. Cisco does not anticipate issuing updated
versions of this advisory unless there is some material change in the
facts. Should there be a significant change in the facts, Cisco may
update this advisory.

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-20030515-saa.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
  * bugtraq () securityfocus com
  * full-disclosure () lists netsys com
  * vulnwatch () vulnwatch org
  * first-teams () first org (includes CERT/CC)
  * cisco () spot colorado edu
  * cisco-nsp () puck nether net
  * comp.dcom.sys.cisco
  * Various internal Cisco mailing lists
   
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 | 2003- May-15,  | Initial     |
| 1.0      | 15:00 UTC      | public      |
|          | (GMT)          | 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/warp/public/707/
sec_incident_response.shtml. This includes instructions for press
inquiries regarding Cisco security notices. All Cisco security advisories
are available at http://www.cisco.com/go/psirt.

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

This notice is Copyright 2003 by Cisco Systems, Inc. This notice may be
redistributed freely after the release date given at the top of the text,
provided that redistributed copies are complete and unmodified, and
include all date and version information.

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

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