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UNIRAS Brief - 302/04 - Cisco Security Advisory: Cisco IOS Malformed BGP Packet Causes Reload



 
-----BEGIN PGP SIGNED MESSAGE-----

- ----------------------------------------------------------------------------------
   UNIRAS (UK Govt CERT) Briefing Notice - 302/04 dated 17.06.04  Time: 15:55  
  UNIRAS is part of NISCC (National Infrastructure Security Co-ordination Centre)
- ---------------------------------------------------------------------------------- 
  UNIRAS material is also available from its website at www.uniras.gov.uk and
         Information about NISCC is available from www.niscc.gov.uk
- ----------------------------------------------------------------------------------

Title
=====

Cisco Security Advisory: Cisco IOS Malformed BGP Packet Causes Reload


Detail
====== 

A Cisco device running IOS and enabled for the Border Gateway Protocol (BGP) 
is vulnerable to a Denial of Service (DOS) attack from a malformed BGP packet. 
The BGP protocol is not enabled by default, and must be configured in order to 
accept traffic from an explicitly defined peer. Unless the malicious traffic 
appears to be sourced from a configured, trusted peer, it would be difficult 
to inject a malformed packet.






- -----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Cisco Security Advisory: Cisco IOS Malformed BGP Packet Causes Reload

Revision 1.0
============

Last Updated June 16 15:00 UTC (GMT)

For Public Release 2004 June 16 15:00 UTC (GMT)

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

Please provide your feedback on this document.

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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
=======

A Cisco device running IOS and enabled for the Border Gateway Protocol (BGP) is 
vulnerable to a Denial of Service (DOS) attack from a malformed BGP packet. The 
BGP protocol is not enabled by default, and must be configured in order to accept 
traffic from an explicitly defined peer. Unless the malicious traffic appears to 
be sourced from a configured, trusted peer, it would be difficult to inject a 
malformed packet.

Cisco has made free software available to address this problem.

This advisory is available at 
http://www.cisco.com/warp/public/707/cisco-sa-20040616-bgp.shtml.

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

Vulnerable Products

This issue affects all Cisco devices running any unfixed version of Cisco IOS 
code and configured for BGP routing.

A router which is running the BGP process will have a line in the config defining 
the AS number, which can be seen by issuing the command show
running-config:

    router bgp <AS number>

This vulnerability is present in any unfixed version of IOS, from the beginning of 
support for the BGP protocol, including versions 9.x, 10.x, 11.x and 12.x.

To determine the software running on a Cisco product, log in to the device and issue 
the show version command to display the system banner. Cisco IOS software will 
identify itself as "Internetwork Operating System Software" or simply "IOS R." 
On the next line of output, the image name will be displayed between parentheses, 
followed by "Version" and the IOS release name. Other Cisco devices will not have 
the show version command or will give different output.

The following example identifies a Cisco product running IOS release 12.0(3) with 
an installed image name of C2500-IS-L:

    Cisco Internetwork Operating System Software IOS (TM)
    
    2500 Software (C2500-IS-L), Version 12.0(3), RELEASE SOFTWARE

The release train label is "12.0."

The next example shows a product running IOS release 12.0(2a)T1 with an image 
name of C2600-JS-MZ:

    Cisco Internetwork Operating System Software IOS (tm)
    C2600 Software (C2600-JS-MZ), Version 12.0(2a)T1, RELEASE SOFTWARE (fc1)

Additional information about Cisco IOS release naming can be found at 
http://www.cisco.com/warp/public/620/1.html.

Products Confirmed Not Vulnerable

Products confirmed not to be vulnerable include devices which cannot participate 
in BGP or cannot be configured for BGP.

Details
=======

The Border Gateway Protocol (BGP) is a routing protocol defined by RFC 1771, and 
designed to manage IP routing in large networks. An affected Cisco device running 
a vulnerable version of Cisco IOS software and enabling the BGP protocol will reload 
when a malformed BGP packet is received. BGP runs over TCP, a reliable transport 
protocol which requires a valid three way handshake before any further messages 
will be accepted. The Cisco IOS implementation of BGP requires the explicit 
definition of a neighbor before a connection can be established, and traffic 
must appear to come from that neighbor. These implementation details make it 
very difficult to send a BGP packet to a Cisco IOS device from an unauthorized source.

A Cisco device receiving an invalid BGP packet will reset and may take several 
minutes to become fully functional. This vulnerability may be exploited repeatedly 
resulting in an extended DOS attack. This issue is documented in bug IDs CSCdu53656 
and CSCea28131.

Impact
======

Successful exploitation of this vulnerability results in a reload of the device. 
Repeated exploitation could result in a sustained DoS attack.

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

Note: Many of the releases in this table were fixed prior to the release of 
other IOS advisories. Read the table carefully to determine if your IOS release 
contains these fixes. Most fixed releases for the TCP and SNMP advisories such 
as http://www.cisco.com/warp/public/707/cisco-sa-20040420-snmp.shtml and 
http://www.cisco.com/warp/public/707/cisco-sa-20040420-tcp-ios.shtml
contained the fixes for this BGP advisory.

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

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 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/.

For software installation and upgrade procedures, see 
http://www.cisco.com/warp/public/130/upgrade_index.shtml.

For a current view of all posted and repaired images for Cisco IOS, please check 
the listing available to registered Cisco.com users at: 
http://www.cisco.com/tacpage/sw-center/sw-ios.shtml.

+------------------------------------------------+
|   Major    | Availability of Repaired Releases |
|  Release   |                 *                 |
|------------+-----------------------------------|
| Affected   |           | Interim |             |
| 11.1-Based | Rebuild   | **      | Maintenance |
| Release    |           |         |             |
|------------+-----------------------------------|
| 11.1       | Migrate to 11.2 or later          |
|------------+-----------------------------------|
| 11.1AA     | Migrate to 11.2P or later         |
|------------+-----------------------------------|
| 11.1CA     | Migrate to 12.0 or later          |
|------------+-----------------------------------|
| 11.1CC     | Migrate to 12.0 or later          |
|------------+-----------------------------------|
| Affected   |           | Interim |             |
| 11.2-Based | Rebuild   | **      | Maintenance |
| Release    |           |         |             |
|------------+-----------+---------+-------------|
| 11.2       | 11.2(26g) |         |             |
|------------+-----------+---------+-------------|
| 11.2P      | 11.2(26)  |         |             |
|            | P7        |         |             |
|------------+-----------------------------------|
| 11.2SA     | Not Vulnerable                    |
|------------+-----------------------------------|
| Affected   |           | Interim |             |
| 11.3-Based | Rebuild   | **      | Maintenance |
| Release    |           |         |             |
|------------+-----------+---------+-------------|
| 11.3       | 11.3(11f) |         |             |
|------------+-----------+---------+-------------|
| 11.3T      | 11.3(11b) |         |             |
|            | T5        |         |             |
|------------+-----------+---------+-------------|
| Affected   |           | Interim |             |
| 12.0-Based | Rebuild   | **      | Maintenance |
| Release    |           |         |             |
|------------+-----------+---------+-------------|
| 12.0       |           |         | 12.0(27)    |
|------------+-----------------------------------|
| 12.0DA     | Migrate to 12.2DA or later        |
|------------+-----------------------------------|
|            | 12.0(21)  |         |             |
|            | S7        |         |             |
|            |-----------+---------+-------------|
|            | 12.0(22)  |         |             |
|            | S2e       |         |             |
|            |-----------+---------+-------------|
|            | 12.0(22)  |         |             |
|            | S3c       |         |             |
|            |-----------+---------+-------------|
|            | 12.0(22)  |         |             |
|            | S4a       |         |             |
|            |-----------+---------+-------------|
| 12.0S      | 12.0(22)  |         |             |
|            | S5        |         |             |
|            |-----------+---------+-------------|
|            | 12.0(23)  |         |             |
|            | S3        |         |             |
|            |-----------+---------+-------------|
|            | 12.0(24)  |         |             |
|            | S2        |         |             |
|            |-----------+---------+-------------|
|            | 12.0(25)  |         |             |
|            | S1        |         |             |
|            |-----------+---------+-------------|
|            |           |         | 12.0(26)S   |
|------------+-----------------------------------|
| 12.0SL     | Migrate to 12.0(23)S3 or later    |
|------------+-----------------------------------|
|            | 12.0(17)  |         |             |
|            | ST10      |         |             |
|            | Available |         |             |
|            | upon      |         |             |
| 12.0ST     | request   |         |             |
|            |-----------+---------+-------------|
|            | 12.0(21)  |         |             |
|            | ST7       |         |             |
|            |-----------------------------------|
|            | Migrate to 12.0(26)S2 or later    |
|------------+-----------------------------------|
| 12.0SV     |           |         | 12.0(27)SV  |
|------------+-----------+---------+-------------|
| 12.0SX     | 12.0(25)  |         |             |
|            | SX        |         |             |
|------------+-----------+---------+-------------|
|            | 12.0(23)  |         |             |
|            | SZ3       |         |             |
|12.0SZ      |-----------+---------+-------------|
|            |           |         | 12.0(26)SZ  |
|            |-----------------------------------|
|            | Migrate to 12.0(26)S2 or later    |
|------------+-----------------------------------|
| 12.0T      | Migrate to 12.1 or later          |
|------------+-----------------------------------|
|            | 12.0(16)  |         |             |
|            | W5(21c)   |         |             |
|            |-----------+---------+-------------|
|            | 12.0(25)  |         |             |
|            | W5(27b)   |         |             |
|12.0W5      |-----------+---------+-------------|
|            | 12.0(26)  |         |             |
|            | W5(28a)   |         |             |
|            |-----------+---------+-------------|
|            | 12.0(27)  |         |             |
|            | W5(29)    |         |             |
|------------+-----------------------------------|
| 12.0WC     | Not Vulnerable                    |
|------------+-----------------------------------|
| 12.0WX     | Migrate to 12.0W5 or later        |
|------------+-----------------------------------|
| 12.0XA     | Migrate to 12.1 latest or later   |
|------------+-----------------------------------|
| 12.0XC     | Migrate to 12.1 latest or later   |
|------------+-----------------------------------|
| 12.0XD     | Migrate to 12.1 latest or later   |
|------------+-----------------------------------|
| 12.0XE     | Migrate to 12.1E latest or later  |
|------------+-----------------------------------|
| 12.0XG     | Migrate to 12.1 latest or later   |
|------------+-----------------------------------|
| 12.0XH     | Migrate to 12.1 latest or later   |
|------------+-----------------------------------|
| 12.0XI     | Migrate to 12.1 latest or later   |
|------------+-----------------------------------|
| 12.0XJ     | Migrate to 12.1 latest or later   |
|------------+-----------------------------------|
| 12.0XK     | Migrate to 12.1T latest or later  |
|------------+-----------------------------------|
| 12.0XL     | Migrate to 12.2 latest or later   |
|------------+-----------------------------------|
| 12.0XN     | Migrate to 12.1 latest or later   |
|------------+-----------------------------------|
| 12.0XP     | Not Vulnerable                    |
|------------+-----------------------------------|
| 12.0XR     | Migrate to 12.2 latest or later   |
|------------+-----------------------------------|
| 12.0XS     | Migrate to 12.1E latest or later  |
|------------+-----------------------------------|
| 12.0XU     | Not Vulnerable                    |
|------------+-----------------------------------|
| Affected   |           | Interim |             |
| 12.1-Based | Rebuild   | **      | Maintenance |
| Release    |           |         |             |
|------------+-----------+---------+-------------|
| 12.1       |           |         | 12.1(20)    |
|------------+-----------------------------------|
| 12.1AA     | Migrate to 12.2 latest or later   |
|------------+-----------------------------------|
|            | Not Vulnerable                    |
|12.1AX      |-----------------------------------|
|            | 12.1AY    | Not Vulnerable        |
|------------+-----------+-----------------------|
| 12.1AZ     |           |         | 12.1(14)AZ  |
|------------+-----------------------------------|
| 12.1DA     | Migrate to 12.2DA or later        |
|------------+-----------------------------------|
| 12.1DB     | Migrate to 12.2B or later         |
|------------+-----------------------------------|
|            | 12.1(6)   |         |             |
|            | E12.0     |         |             |
|            |-----------+---------+-------------|
|            | 12.1(8b)  |         |             |
|            | E14       |         |             |
|            |-----------+---------+-------------|
|            | 12.1(11b) |         |             |
|            | E12.0     |         |             |
|            |-----------+---------+-------------|
|            | 12.1(12c) |         |             |
| 12.1E      | E7        |         |             |
|            |-----------+---------+-------------|
|            | 12.1(13)  |         |             |
|            | E6        |         |             |
|            |-----------+---------+-------------|
|            | 12.1(14)  |         |             |
|            | E4        |         |             |
|            |-----------+---------+-------------|
|            | 12.1(19)E |         |             |
|            |-----------+---------+-------------|
|            |           |         | 12.1(20)E   |
|------------+-----------+---------+-------------|
| 12.1EA     | 12.1(14)  |         |             |
|            | EA1       |         |             |
|------------+-----------+---------+-------------|
| 12.1EB     | 12.1(14)  |         |             |
|            | EB1       |         |             |
|------------+-----------+---------+-------------|
| 12.1EC     |           |         | 12.1(19)EC  |
|------------+-----------+---------+-------------|
| 12.1EO     |           |         | 12.1(19)EO  |
|------------+-----------+---------+-------------|
| 12.1EV     | 12.1(12c) |         |             |
|            | EV2       |         |             |
|------------+-----------+---------+-------------|
| 12.1EW     |           |         | 12.1(19)EW  |
|------------+-----------------------------------|
| 12.1EX     | Migrate to 12.1(14)E4 or later    |
|------------+-----------------------------------|
| 12.1EY     | Migrate to 12.1(14)E4 or later    |
|------------+-----------------------------------|
| 12.1T      | 12.1(5)   |         |             |
|            | T19       |         |             |
|------------+-----------------------------------|
| 12.1XA     | Migrate to 12.1(5)T19 or later    |
|------------+-----------------------------------|
| 12.1XB     | Migrate to 12.1(5)T19 or later    |
|------------+-----------------------------------|
| 12.1XC     | Migrate to 12.1(5)T19 or later    |
|------------+-----------------------------------|
| 12.1XD     | Migrate to 12.2 or later          |
|------------+-----------------------------------|
| 12.1XE     | Migrate to 12.1E latest or later  |
|------------+-----------------------------------|
| 12.1XF     | Migrate to 12.2(4)T6 or later     |
|------------+-----------------------------------|
| 12.1XG     | Migrate to 12.2(4)T6 or later     |
|------------+-----------------------------------|
| 12.1XH     | Migrate to 12.2 or later          |
|------------+-----------------------------------|
| 12.1XI     | Migrate to 12.2 latest or later   |
|------------+-----------------------------------|
| 12.1XJ     | Migrate to 12.2(4)T6 or later     |
|------------+-----------------------------------|
| 12.1XL     | Migrate to 12.2T latest or later  |
|------------+-----------------------------------|
| 12.1XM     | Migrate to 12.2T latest or later  |
|------------+-----------------------------------|
| 12.1XP     | Migrate to 12.2(4)T6 or later     |
|------------+-----------------------------------|
| 12.1XQ     | Migrate to 12.2T latest or later  |
|------------+-----------------------------------|
| 12.1XR     | Migrate to 12.2T latest or later  |
|------------+-----------------------------------|
| 12.1XT     | Migrate to 12.2(4)T6 or later     |
|------------+-----------------------------------|
| 12.1XU     | Migrate to 12.2T latest or later  |
|------------+-----------------------------------|
| 12.1XV     | Migrate to 12.2XB or later        |
|------------+-----------------------------------|
| 12.1XY     | Migrate to 12.2XB or later        |
|------------+-----------------------------------|
| 12.1YA     | Migrate to 12.2(8)T10 or later    |
|------------+-----------------------------------|
| 12.1YB     | Migrate to 12.2(4)T6 or later     |
|------------+-----------------------------------|
| 12.1YC     | Migrate to 12.2(8)T10 or later    |
|------------+-----------------------------------|
| 12.1YD     | Migrate to 12.2(8)T10 or later    |
|------------+-----------------------------------|
| 12.1YH     | Migrate to 12.2(13)T5 or later    |
|------------+-----------------------------------|
| 12.1YJ     | Not Vulnerable                    |
|------------+-----------------------------------|
| Affected   |           | Interim |             |
| 12.2-Based | Rebuild   | **      | Maintenance |
| Release    |           |         |             |
|------------+-----------+---------+-------------|
|            | 12.2(10d) |         |             |
|            |-----------+---------+-------------|
|            | 12.2(12e) |         |             |
|            |-----------+---------+-------------|
|            | 12.2(12h) |         |             |
| 12.2       | M1        |         |             |
|            |-----------+---------+-------------|
|            | 12.2(13c) |         |             |
|            |-----------+---------+-------------|
|            | 12.2(16a) |         |             |
|            |-----------+---------+-------------|
|            |           |         | 12.2(17)    |
|------------+-----------+---------+-------------|
| 12.2B      | 12.2(15)  |         |             |
|            | B1        |         |             |
|------------+-----------+---------+-------------|
| 12.2BC     | 12.2(15)  |         |             |
|            | BC1       |         |             |
|------------+-----------------------------------|
| 12.2BW     | Migrate to 12.2(15)T12 or later   |
|------------+-----------------------------------|
| 12.2BX     |           |         | 12.2(16)BX  |
|------------+-----------------------------------|
| 12.2BY     | Migrate to 12.2(15)B1 or later    |
|------------+-----------------------------------|
| 12.2BZ     | Migrate to 12.2(16)BX or later    |
|------------+-----------------------------------|
| 12.2CX     |           |         | 12.2(15)CX  |
|------------+-----------+---------+-------------|
| 12.2DA     | 12.2(12)  |         |             |
|            | DA6       |         |             |
|------------+-----------------------------------|
| 12.2DD     | Migrate to 12.2(15)B1 or later    |
|------------+-----------------------------------|
| 12.2DX     | Migrate to 12.2(15)B1 or later    |
|------------+-----------------------------------|
| 12.2EW     |           |         | 12.2(18)EW  |
|------------+-----------+---------+-------------|
| 12.2JA     |           |         | 12.2(13)JA  |
|------------+-----------+---------+-------------|
|            | 12.2(14)  |         |             |
| 12.2S      | S2        |         |             |
|            |-----------+---------+-------------|
|            |           |         | 12.2(18)S   |
|------------+-----------+---------+-------------|
| 12.2SE     |           |         | 12.2(18)SE  |
|------------+-----------+---------+-------------|
| 12.2SU     |           |         | 12.2(14)SU  |
|------------+-----------+---------+-------------|
| 12.2SV     |           |         | 12.2(18)SV  |
|------------+-----------+---------+-------------|
| 12.2SW     |           |         | 12.2(18)SW  |
|------------+-----------+---------+-------------|
| 12.2SX     | 12.2(14)  |         |             |
|            | SX2       |         |             |
|------------+-----------+---------+-------------|
| 12.2SXA    | 12.2(17b) |         |             |
|            | SXA       |         |             |
|------------+-----------+---------+-------------|
| 12.2SXB    | 12.2(17d) |         |             |
|            | SXB       |         |             |
|------------+-----------+---------+-------------|
| 12.2SY     |           |         | 12.2(14)SY  |
|------------+-----------+---------+-------------|
| 12.2SZ     | 12.2(14)  |         |             |
|            | SZ2       |         |             |
|------------+-----------+---------+-------------|
|            | 12.2(4)T6 |         |             |
|            |-----------+---------+-------------|
|            | 12.2(8)   |         |             |
|            | T10       |         |             |
|            |-----------+---------+-------------|
|            | 12.2(11)  |         |             |
| 12.2T      | T9        |         |             |
|            |-----------+---------+-------------|
|            | 12.2(13)  |         |             |
|            | T5        |         |             |
|            |-----------+---------+-------------|
|            | 12.2(15)  |         |             |
|            | T4        |         |             |
|------------+-----------------------------------|
| 12.2XA     | Migrate to 12.2(11)T9 or later    |
|------------+-----------------------------------|
| 12.2XB     | 12.2(2)   |         |             |
|            | XB16      |         |             |
|------------+-----------------------------------|
| 12.2XD     | Migrate to 12.2(8)T10 or later    |
|------------+-----------------------------------|
| 12.2XE     | Migrate to 12.2(8)T10 or later    |
|------------+-----------------------------------|
| 12.2XG     | Migrate to 12.2(8)T10 or later    |
|------------+-----------------------------------|
| 12.2XH     | Migrate to 12.2(11)T9 or later    |
|------------+-----------------------------------|
| 12.2XI     | Migrate to 12.2(11)T9 or later    |
|------------+-----------------------------------|
| 12.2XJ     | Migrate to 12.2(11)T9 or later    |
|------------+-----------------------------------|
| 12.2XK     | Migrate to 12.2(11)T9 or later    |
|------------+-----------------------------------|
| 12.2XL     | Migrate to 12.2(15)T4 or later    |
|------------+-----------------------------------|
| 12.2XM     | Migrate to 12.2(15)T4 or later    |
|------------+-----------------------------------|
| 12.2XN     | Migrate to 12.2(11)T9 or later    |
|------------+-----------------------------------|
| 12.2XQ     | Migrate to 12.2(11)T9 or later    |
|------------+-----------------------------------|
| 12.2XS     | Migrate to 12.2(11)T9 or later    |
|------------+-----------------------------------|
| 12.2XT     | Migrate to 12.2(11)T9 or later    |
|------------+-----------------------------------|
| 12.2XU     | Migrate to 12.2(15)T12 or later   |
|------------+-----------------------------------|
| 12.2XW     | Migrate to 12.2(11)T9 or later    |
|------------+-----------------------------------|
| 12.2YA     | Migrate to 12.2(15)T4 or later    |
|------------+-----------------------------------|
| 12.2YB     | Migrate to 12.2(15)T4 or later    |
|------------+-----------------------------------|
| 12.2YC     | Migrate to 12.2(11)T11 or later   |
|------------+-----------------------------------|
| 12.2YD     | Migrate to 12.2(8)YY or later     |
|------------+-----------------------------------|
| 12.2YE     | Migrate to 12.2S or later         |
|------------+-----------------------------------|
| 12.2YF     | Migrate to 12.2(15)T4 or later    |
|------------+-----------------------------------|
| 12.2YG     | Migrate to 12.2(13)T5 or later    |
|------------+-----------------------------------|
| 12.2YH     | Migrate to 12.2(15)T4 or later    |
|------------+-----------------------------------|
| 12.2YJ     | Migrate to 12.2(15)T4 or later    |
|------------+-----------------------------------|
| 12.2YL     | Migrate to 12.3(2)T or later      |
|------------+-----------------------------------|
| 12.2YM     | Migrate to 12.3(2)T or later      |
|------------+-----------------------------------|
| 12.2YN     | Migrate to 12.3(2)T or later      |
|------------+-----------------------------------|
| 12.2YO     | Migrate to 12.2(14)SY or later    |
|------------+-----------------------------------|
| 12.2YP     | 12.2(11)  |         |             |
|            | YP1       |         |             |
|------------+-----------------------------------|
| 12.2YQ     | Migrate to 12.3(4)T or later      |
|------------+-----------------------------------|
| 12.2YR     | Migrate to 12.3(4)T or later      |
|------------+-----------------------------------|
| 12.2YS     | Migrate to 12.3T or later         |
|------------+-----------------------------------|
| 12.2YT     | Migrate to 12.2(15)T4 or later    |
|------------+-----------------------------------|
| 12.2YU     | Migrate to 12.3(4)T or later      |
|------------+-----------------------------------|
| 12.2YV     | Migrate to 12.3(4)T or later      |
|------------+-----------------------------------|
| 12.2YW     | Migrate to 12.3(2)T or later      |
|------------+-----------------------------------|
| 12.2YX     | Migrate to 12.2(14)SU or later    |
|------------+-----------------------------------|
| 12.2YY     | 12.2(8)   |         |             |
|            | YY3       |         |             |
|------------+-----------------------------------|
| 12.2YZ     | Migrate to 12.2(14)SZ or later    |
|------------+-----------------------------------|
| 12.2ZA     | 12.2(14)  |         |             |
|            | ZA2       |         |             |
|------------+-----------------------------------|
| 12.2ZB     | Migrate to 12.3T or later         |
|------------+-----------------------------------|
| 12.2ZC     | Migrate to 12.3T or later         |
|------------+-----------------------------------|
| 12.2ZE     | Migrate to 12.3 or later          |
|------------+-----------------------------------|
| 12.2ZF     | Migrate to 12.3(4)T or later      |
|------------+-----------------------------------|
| 12.2ZG     | Migrate to 12.3(4)T or later      |
|------------+-----------------------------------|
| 12.2ZH     | Migrate to 12.3(4)T or later      |
|------------+-----------------------------------|
| 12.2ZI     | Migrate to 12.2(18)S or later     |
|------------+-----------------------------------|
| 12.2ZK     |           |         | 12.2(15)ZK  |
|------------+-----------+---------+-------------|
| 12.2ZL     |           |         | 12.2(15)ZL  |
|------------+-----------------------------------|
| 12.2ZN     | Migrate to 12.3(2)T or later      |
|------------+-----------------------------------|
| 12.2ZO     |           |         | 12.2(15)ZO  |
|------------+-----------+---------+-------------|
| 12.2ZP     |           |         | 12.2(13)ZP  |
|------------+-----------+---------+-------------|
| Affected   |           | Interim |             |
| 12.3-Based | Rebuild   | **      | Maintenance |
| Release    |           |         |             |
|------------+-----------------------------------|
| 12.3       | Not Vulnerable                    |
|------------+-----------------------------------|
| 12.3T      | Not Vulnerable                    |
+------------------------------------------------+

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/tacpage/sw-center.

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@xxxxxxxxx

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@xxxxxxxxx" or "security-alert@xxxxxxxxx" 
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 as otherwise set forth at Cisco.com Downloads at 
http://www.cisco.com/public/sw-center/sw-usingswc.shtml.

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

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.

For additional information regarding BGP security risk assessment, mitigation 
techniques, and deployment best practices, please consult 
ftp:// ftp-eng.cisco.com/cons/isp/security/BGP-Risk-Assesment-v.pdf.

BGP MD5

Under normal circumstances, due to inherent security factors in the TCP protocol
such as sequence number checks, it is difficult but possible to forge an appropriate 
packet to exploit this problem. Configuring your Cisco IOS device for BGP MD5 
authentication is a valid workaround to protect the vulnerable device.

This can be configured as shown in the following example:

    router(config)# router bgp 
     router(config-router)# neighbor <IP_address> password <enter_your_secret_here>

It is necessary to configure the same shared MD5 secret on both peers and at the same 
time. Failure to do so will break the existing BGP session and the new session will 
not get established until the exact same secret is configured on both devices. For a 
detailed discussion on how to configure BGP, refer to the following document:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_configuration_guide_chapter09186a00800ca571.html

Once the secret is configured, it is prudent to change it periodically. The exact 
period must fit within your company security policy but it should not be longer 
than a few months. When changing the secret, again it must be done at the same 
time on both devices. Failure to do so will break your existing BGP session. 
The exception is if your Cisco IOS software release contains the integrated 
CSCdx23494 fix on both sides of the connection. With this fix, the BGP session 
will not be terminated when the MD5 secret is changed only on one side. 
The BGP updates, however, will not be processed until either the same secret 
is configured on both devices or the secret is removed from both devices.

Infrastructure Access Control Lists

Although it is often difficult to block traffic transiting your network, 
it is possible to identify traffic which should never be allowed to target 
your infrastructure devices and block that traffic at the border of your 
network. Infrastructure ACLs are considered 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 white paper 
entitled "Protecting Your Core: Infrastructure Protection Access Control Lists" 
presents guidelines and recommended deployment techniques for infrastructure protection
ACLs:

http://www.cisco.com/warp/public/707/iacl.html

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

The research which led to this vulnerability being discovered was announced in a 
public announcement at NANOG in June 2003. The Cisco PSIRT team is not aware of 
any malicious use of the vulnerabilities described in this advisory. We were made 
aware of this issue through internal testing as well as notification from a 
research team at the University of California at Santa Barbara.

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

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

This Advisory is provided on an "as is" basis and does not imply any kind 
of guarantee or warranty of any kind. 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 anytime.

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

This advisory will be posted on Cisco's worldwide website at 
http://www.cisco.com/warp/public/707/cisco-sa-20040616-bgp.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@xxxxxxxxx
  * first-teams@xxxxxxxxx (includes CERT/CC)
  * bugtraq@xxxxxxxxxxxxxxxxx
  * vulnwatch@xxxxxxxxxxxxx
  * cisco@xxxxxxxxxxxxxxxxx
  * cisco-nsp@xxxxxxxxxxxxxxx
  * full-disclosure@xxxxxxxxxxxxxxxx
  * comp.dcom.sys.cisco@xxxxxxxxxxxxxxxxxx

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  | 16-June-2004 | 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/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.

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

All contents are Copyright C 1992-2004 Cisco Systems, Inc. All rights reserved.

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

For additional information or assistance, please contact the HELP Desk by 
telephone or Not Protectively Marked information may be sent via 
EMail to: uniras@xxxxxxxxxxxx

Office Hours:
Mon - Fri: 08:30 - 17:00 Hrs
Tel: +44 (0) 20 7821 1330 Ext 4511
Fax: +44 (0) 20 7821 1686

Outside of Office Hours:
On Call Duty Officer:
Tel: +44 (0) 20 7821 1330 and follow the prompts

- ----------------------------------------------------------------------------------
UNIRAS wishes to acknowledge the contributions of Cisco Systems for the information 
contained in this Briefing. 
- ----------------------------------------------------------------------------------
This Briefing contains the information released by the original author. Some 
of the information may have changed since it was released. If the vulnerability 
affects you, it may be prudent to retrieve the advisory from the canonical site 
to ensure that you receive the most current information concerning that problem.

Reference to any specific commercial product, process, or service by trade 
name, trademark manufacturer, or otherwise, does not constitute or imply 
its endorsement, recommendation, or favouring by UNIRAS or NISCC.  The views 
and opinions of authors expressed within this notice shall not be used for 
advertising or product endorsement purposes.

Neither UNIRAS or NISCC shall also accept responsibility for any errors 
or omissions contained within this briefing notice. In particular, they shall 
not be liable for any loss or damage whatsoever, arising from or in connection 
with the usage of information contained within this notice.

UNIRAS is a member of the Forum of Incident Response and Security Teams (FIRST) 
and has contacts with other international Incident Response Teams (IRTs) in 
order to foster cooperation and coordination in incident prevention, to prompt 
rapid reaction to incidents, and to promote information sharing amongst its 
members and the community at large. 
- ----------------------------------------------------------------------------------
<End of UNIRAS Briefing>

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