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Cisco Security Advisory: Cisco IOS BGP Attribute Corruption Vulnerability
=========================================================================
Revision 1.0
For Public Release 2001 May 10 08:00 AM US/Pacific (UTC -0700)
------------------------------------------------------------------------
Summary
=======
A Border Gateway Protocol (BGP) UPDATE contains Network Layer
Reachability Information (NLRI) and attributes that describe the path to
the destination. An unrecognized transitive attribute can cause failures in
Cisco IOS routers, ranging from a crash upon receipt of the unrecognized
transitive attribute, to a later failure upon attempt to clear the
unrecognized transitive attribute. Specific but common configurations are
affected, and described below. The failure was discovered because of a
malfunction in the BGP implementation of another vendor. There is no
workaround. Affected customers are urged to upgrade to fixed code.
This vulnerability has been assigned Cisco bug ID CSCdt79947.
The complete text of this advisory will be located at
http://www.cisco.com/warp/public/707/ios-bgp-attr-corruption-pub.shtml
Affected Products
=================
Configurations including BGP4 Prefix Filtering with Inbound Route Maps are
vulnerable. BGP with prefix or inbound routemap filtering was introduced
in Cisco IOSŪ Software version 11.2 The following versions of Cisco IOS
Software are affected and listed in the table below: 11.CC and its
derivatives, 11.2 and its derivaties, 11.3, 11.3T, 12.0, 12.0S and special
branches taken out of 12.0 are all affected. The versions of Cisco IOS
Software based on 12.1, 12.0(5)T, 12.2, 12.0ST, and 12.1(E) are not
affected. The following products are affected if they run a Cisco IOS
software release that has the defect. To determine if a Cisco product is
running an affected IOS, log in to the device and issue the show version
command. Cisco IOS software will identify itself as "Internetwork Operating
System Software" or "IOS (tm)" software and will display a version number.
Other Cisco devices either will not have the show version command, or will
give different output. Compare the version number obtained from the router
with the versions presented in the Software Versions and Fixes section
below.
Cisco devices that may be running with affected Cisco IOS software releases
include:
* Cisco routers in the AGS/MGS/CGS/AGS+, IGS, RSM, 800, ubr900, 1000,
1400, 1500, 1600, 1700, 2500, 2600, 3000, 3600, 3800, 4000, 4500,
4700, AS5200, AS5300, AS5800, 6400, 7000, 7200, ubr7200, 7500, and
12000 series.
Cisco devices that may be running Cisco IOS Software, but do NOT support
BGP and are therefore not vulnerable include:
* Most recent versions of the LS1010 ATM switch.
* The Catalyst 2900XL LAN switch only if it is running IOS.
* The Catalyst 1900, 2800, 2900, 3000, and 5000 series LAN switches.
* The Cisco DistributedDirector.
If you are not running Cisco IOS software, you are not affected by this
vulnerability. If you are not running BGP, you are not affected by this
vulnerability.
Cisco products that do not run Cisco IOS software and are not affected by
this defect include, but are not limited to:
* 700 series dialup routers (750, 760, and 770 series) are not affected.
* The Catalyst 6000 is not affected if it is not running IOS.
* WAN switching products in the IGX and BPX lines are not affected.
* The MGX (formerly known as the AXIS shelf) is not affected.
* No host-based software is affected.
* The Cisco PIX Firewall is not affected.
* The Cisco LocalDirector is not affected.
* The Cisco Cache Engine is not affected.
Details
=======
A Border Gateway Protocol (BGP) UPDATE contains Network Layer Reachability
Information (NLRI) and attributes that describe the path to the
destination. Each path attribute is a type, length, value (TLV) object.
This failure occurs as a result of memory corruption and only in
configurations using specific inbound route filtering. The failure was
discovered because of a malfunction in the BGP implementation of another
vendor. There is no workaround.
Impact
======
The vulnerability can be exercised repeatedly, affecting core routers,
creating widespread network outages. This vulnerability can only be
exercised in configurations that include both BGP and inbound route
filtering on affected software.
Software Versions and Fixes
===========================
The following table summarizes the Cisco IOS software releases that are
known to be affected, and the earliest estimated dates of availability for
the recommended fixed versions. Dates are always tentative and subject to
change.
Each row of the table 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 and the
anticipated date of availability for each are listed in the "Rebuild",
"Interim", and "Maintenance" columns. A device running any release in the
given train that is earlier than the release in a specific column (less
than the earliest fixed release) is known to be vulnerable, and it should
be upgraded at least to the indicated release or a later version (greater
than the earliest fixed release label).
When selecting a release, keep in mind the following definitions:
Maintenance
Most heavily tested and highly recommended release of any label
in a 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 effect the repair.
Interim
Built at regular intervals between maintenance releases and
receive less testing. Interims should be selected only if there
is no other suitable release that addresses the vulnerability,
and interim images should be upgraded to the next available
maintenance release as soon as possible. Interim releases are not
available via manufacturing, and usually they are not available
for customer download from CCO without prior arrangement with the
Cisco TAC.
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 TAC for
assistance as shown later in this notice.
More information on Cisco IOS Software release names and abbreviations is
available at
http://www.cisco.com/warp/public/cc/pd/iosw/iore/prodlit/537_pp.htm.
+===========================================================================+
Train Description of Availability of Fixed Releases*
Image or Platform
+===========================================================================+
11.0-based Releases Rebuild Interim Maintenance
+===========================================================================+
11.0 Major GD release Not vulnerable
for all platforms
+===========================================================================+
11.1-based Releases Rebuild Interim Maintenance
+===========================================================================+
11.1 Major release for Not vulnerable
all platforms
+----------+------------------+-----------------+------------+--------------+
ED release for
11.1AA access servers: Not vulnerable
1600, 3200, and
5200 series.
+----------+------------------+-----------------+------------+--------------+
Platform-specific End of Engineering
11.1CA support for 7500,
7200, 7000, and
RSP Not scheduled
+----------+------------------+-----------------+------------+--------------+
ISP train: added
support for FIB, 11.1(36)CC2
11.1CC CEF, and NetFlow
on 7500, 7200, Not scheduled
7000, and RSP
+----------+------------------+-----------------+------------+--------------+
Added support for End of Engineering
11.1CT Tag Switching on
7500, 7200, 7000,
and RSP Upgrade recommended to 12.0(14)ST
+----------+------------------+-----------------+------------+--------------+
11.1IA Distributed Not Vulnerable
Director only
+===========================================================================+
11.2-based Releases Rebuild Interim Maintenance
+===========================================================================+
Major release, End of Engineering
11.2 general
deployment Not scheduled
+----------+------------------+-----------------+------------+--------------+
Platform-specific
support for IBM End of Engineering
11.2BC networking, CIP,
and TN3270 on
7500, 7000, and Upgrade recommended to 12.1(8)
RSP
+----------+------------------+-----------------+------------+--------------+
End of Engineering
11.2F Feature train for
all platforms Upgrade recommended
+----------+------------------+-----------------+------------+--------------+
Early deployment End of Engineering
11.2GS release to
support 12000 GSR Upgrade recommended to 12.0(17)S
+----------+------------------+-----------------+------------+--------------+
End of Engineering
11.2P New platform
support Upgrade recommended to 12.0(17)
+----------+------------------+-----------------+------------+--------------+
11.2SA Catalyst 2900XL Not vulnerable
switch only
+----------+------------------+-----------------+------------+--------------+
11.2WA3 LightStream 1010 Not vulnerable
ATM switch
+----------+------------------+-----------------+------------+--------------+
Initial release End of Engineering
11.2(4)XAf for the 1600 and
3600 Upgrade recommended
+----------+------------------+-----------------+------------+--------------+
Initial release
for the 5300 and End of Engineering
11.2(9)XA digital modem
support for the Upgrade recommended
3600
+===========================================================================+
11.3-based Releases Rebuild Interim Maintenance
+===========================================================================+
End of Engineering
11.3 Major release for
all platforms Upgrade recommended to 12.0(17)
+----------+------------------+-----------------+------------+--------------+
ED for dial
platforms and End of Engineering
11.3AA access servers:
5800, 5200, 5300, Upgrade recommended to 12.0(17)
7200
+----------+------------------+-----------------+------------+--------------+
Early deployment End of Engineering
11.3DA train for ISP
DSLAM 6200
platform Upgrade recommended to 12.1(5)DA1
+----------+------------------+-----------------+------------+--------------+
Early deployment
train for End of Engineering
ISP/Telco/PTT
11.3DB xDSL broadband
concentrator
platform, (NRP) Upgrade recommended to 12.1(4)DB1
for 6400
+----------+------------------+-----------------+------------+--------------+
Short-lived ED End of Engineering
11.3HA release for ISR
3300 (SONET/SDH
router) Upgrade recommended to 12.0
+----------+------------------+-----------------+------------+--------------+
MC3810 Not available
11.3MA functionality
only Not scheduled
+----------+------------------+-----------------+------------+--------------+
Voice over IP, End of Engineering
11.3NA media
convergence,
various platforms Upgrade recommended to 12.0(5)T
+----------+------------------+-----------------+------------+--------------+
Early deployment End of Engineering
11.3T major release,
feature-rich for
early adopters Upgrade recommended to 12.0(17)
+----------+------------------+-----------------+------------+--------------+
Multilayer
Switching and
Multiprotocol End of Engineering
over ATM
11.3WA4 functionality for
Catalyst 5000
RSM, 4500, 4700, Upgrade recommended
7200, 7500,
LightStream 1010
+----------+------------------+-----------------+------------+--------------+
End of Engineering
11.3(2)XA Introduction of
ubr7246 and 2600 Upgrade recommended
+===========================================================================+
12.0-based Releases Rebuild Interim Maintenance
+===========================================================================+
General
12.0 deployment 12.0(17)
release for all 2001-Apr-23
platforms
+----------+------------------+-----------------+------------+--------------+
Unavailable
12.0DA xDSL support:
6100, 6200 Upgrade recommended to 12.1(5)DA1
+----------+------------------+-----------------+------------+--------------+
Early Deployment
(ED) release,
which delivers Unavailable
support for the
12.0DB Cisco 6400
Universal Access
Concentrator
(UAC) for Node Upgrade recommended to 12.1(4)DB1
Switch Processor
(NSP)
+----------+------------------+-----------------+------------+--------------+
Early Deployment
(ED) release,
which delivers Unavailable
support for the
12.0DC Cisco 6400
Universal Access
Concentrator
(UAC) for Node Upgrade recommended to 12.1(5)DC
Route Processor
(NRP)
+----------+------------------+-----------------+------------+--------------+
12.0(15)S3, 12.0(17)S
12.0(16)S1 12.0(16.06)S 2001-May-07
12.0S Core/ISP support:
GSR, RSP, c7200 2001-April-23
2001-April-30
+----------+------------------+-----------------+------------+--------------+
12.0SC Cable/broadband Not vulnerable
ISP: ubr7200
+----------+------------------+-----------------+------------+--------------+
12.0SL 10000 ESR: c10k Not vulnerable
+----------+------------------+-----------------+------------+--------------+
Cisco IOS
software
Release12.0ST is
an early
deployment (ED)
12.0ST release for the Not vulnerable
Cisco 7200,
7500/7000RSP and
12000 (GSR)
series routers
for Service
Providers (ISPs).
+----------+------------------+-----------------+------------+--------------+
Early
Deployment(ED):
12.0T VPN, Distributed 12.0(5)T
Director, various
platforms
+----------+------------------+-----------------+------------+--------------+
Catalyst
switches: 12.0(10)W5(18g)
cat2948g-l3, 2001-Apr-20
cat4232
12.0W5 +------------------+-----------------+------------+--------------+
cat8510c,
cat8540c, c6msm, 12.0(16)W5(21)
ls1010, cat8510m,
cat8540m, c5atm 2001-May-21
+----------+------------------+-----------------+------------+--------------+
Catalyst
12.0WT switches: Not vulnerable
cat4840g
+----------+------------------+-----------------+------------+--------------+
Early Deployment Unavailable
12.0XA (ED): limited Upgrade recommended to 12.1(8), available
platforms 2001-Apr-23
+----------+------------------+-----------------+------------+--------------+
Short-lived early Unavailable
12.0XB deployment Upgrade recommended to 12.1(8), available
release 2001-Apr-23
+----------+------------------+-----------------+------------+--------------+
Early Deployment Unavailable
12.0XC (ED): limited Upgrade recommended to 12.1(8), available
platforms 2001-Apr-23
+----------+------------------+-----------------+------------+--------------+
Early Deployment Unavailable
12.0XD (ED): limited Upgrade recommended to 12.1(8), available
platforms 2001-Apr-23
+----------+------------------+-----------------+------------+--------------+
Early Deployment
12.0XE (ED): limited Not Vulnerable
platforms
+----------+------------------+-----------------+------------+--------------+
Early Deployment Unavailable
12.0XF (ED): limited Upgrade recommended to 12.1(8), available
platforms 2001-Apr-23
+----------+------------------+-----------------+------------+--------------+
Early Deployment Unavailable
12.0XG (ED): limited Upgrade recommended to 12.1(8), available
platforms 2001-Apr-23
+----------+------------------+-----------------+------------+--------------+
Early Deployment Unavailable
12.0XH (ED): limited Upgrade recommended to 12.1(8), available
platforms 2001-Apr-23
+----------+------------------+-----------------+------------+--------------+
Early Deployment Unavailable
12.0XI (ED): limited Upgrade recommended to 12.1(8), available
platforms 2001-Apr-23
+----------+------------------+-----------------+------------+--------------+
Early Deployment Unavailable
12.0XJ (ED): limited Upgrade recommended to 12.1(8), available
platforms 2001-Apr-23
+----------+------------------+-----------------+------------+--------------+
Early Deployment
12.0XK (ED): limited Not vulnerable
platforms
+----------+------------------+-----------------+------------+--------------+
Early Deployment
12.0XL (ED): limited Not vulnerable
platforms
+----------+------------------+-----------------+------------+--------------+
Short-lived early
12.0XM deployment Not vulnerable
release
+----------+------------------+-----------------+------------+--------------+
Early Deployment
12.0XN (ED): limited Not vulnerable
platforms
+----------+------------------+-----------------+------------+--------------+
Early Deployment
12.0XP (ED): limited Not vulnerable
platforms
+----------+------------------+-----------------+------------+--------------+
Short-lived early
12.0XQ deployment Not vulnerable
release
+----------+------------------+-----------------+------------+--------------+
Short-lived early
12.0XR deployment Not vulnerable
release
+----------+------------------+-----------------+------------+--------------+
Short-lived early
12.0XS deployment Not vulnerable
release
+----------+------------------+-----------------+------------+--------------+
Early Deployment
12.0XU (ED): limited Not vulnerable
platforms
+----------+------------------+-----------------+------------+--------------+
Short-lived early
12.0XV deployment Not vulnerable
release
+===========================================================================+
12.1-based and Later
Releases Rebuild Interim Maintenance
+===========================================================================+
General
12.1 deployment Not vulnerable
release for all
platforms
+===========================================================================+
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.
+===========================================================================+
Getting Fixed Software
Cisco is offering free software upgrades to remedy this vulnerability for
all affected customers.
Customers with contracts should obtain upgraded software through their
regular update channels. For most customers, this means that upgrades
should be obtained via the Software Center on Cisco's Worldwide Web site at
http://www.cisco.com.
Customers without contracts 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
See http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for
additional TAC contact information, including instructions and e-mail
addresses for use in various languages.
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 are no known workarounds for this vulnerablity. Please upgrade to
fixed versions.
Exploitation and Public Announcements
=====================================
Cisco has had no reports of malicious exploitation of this vulnerability.
The failure was discovered because of a malfunction in the BGP
implementation of another vendor, which caused a series of crashes that led
to the identification of this issue.
Cisco knows of no public announcements of this vulnerability before the
date of this notice.
Status of This Notice: FINAL
============================
This is a final notice. Although Cisco cannot guarantee the accuracy of all
statements in this notice, all of the facts have been checked to the best
of our ability. Cisco does not anticipate issuing updated versions of
this notice unless there is some material change in the facts. Should there
be a significant change in the facts, Cisco may update this notice.
Distribution
============
This notice will be posted on Cisco's Worldwide Web site at
http://www.cisco.com/warp/public/707/ios-bgp-attr-corruption-pub.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
* firewalls@lists.gnac.com
* 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 notice, if any, will be placed on Cisco's Worldwide
Web server, but may or may not be actively announced on mailing lists or
newsgroups. Users concerned about this problem are encouraged to check the
URL given above for any updates.
Revision History
================
Revision Number1.0 Initial 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
Web site at
http://www.cisco.com/warp/public/707/sec_incident_response.shtml. This
includes instructions for press inquiries regarding Cisco security notices.
------------------------------------------------------------------------
This notice is Copyright 2001 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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