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Cisco Security Advisory

Cisco IOS Software Malformed Border Gateway Protocol Attribute Vulnerability

High
Advisory ID:
cisco-sa-20120926-bgp
First Published:
2012 September 26 16:00 GMT
Last Updated:
2012 October 4 15:33 GMT
Version 1.1:
Final
Workarounds:
See below
CVE-2012-4617
CWE-399
CVSS Score:
Base 7.1, Temporal 5.9Click Icon to Copy Verbose Score
AV:N/AC:M/Au:N/C:N/I:N/A:C/E:F/RL:OF/RC:C
CVE-2012-4617
CWE-399

Summary

  • Cisco IOS Software contains a vulnerability in the Border Gateway Protocol (BGP) routing protocol feature.

    The vulnerability can be triggered when the router receives a malformed attribute from a peer on an existing BGP session.

    Successful exploitation of this vulnerability can cause all BGP sessions to reset. Repeated exploitation may result in an inability to route packets to BGP neighbors during reconvergence times.

    Cisco has released software updates that address this vulnerability. There are no workarounds for this vulnerability. This advisory is available at the following link:
    https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120926-bgp

    Note: The September 26, 2012, Cisco IOS Software Security Advisory bundled publication includes nine Cisco Security Advisories. Eight of the advisories address vulnerabilities in Cisco IOS Software, and one advisory addresses a vulnerability in Cisco Unified Communications Manager. Each Cisco IOS Software Security Advisory lists the Cisco IOS Software releases that correct the vulnerability or vulnerabilities detailed in the advisory as well as the Cisco IOS Software releases that correct all Cisco IOS Software vulnerabilities in the September 2012 bundled publication.

    Individual publication links are in "Cisco Event Response: Semi-Annual Cisco IOS Software Security Advisory Bundled Publication" at the following link:

    http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_sep12.html

Affected Products

  • This vulnerability affects Cisco IOS Software, Cisco IOS-XR Software, and Cisco IOS-XE Software.

    Vulnerable Products

    A Cisco IOS router is potentially vulnerable when it is running an affected version of Cisco IOS Software, BGP routing is enabled on the router, and the router has at least one established BGP neighbor session. For more information on affected versions, see the "Software Versions and Fixes" section below.

    A device running Cisco IOS XR has a vulnerable configuration if BOTH of the following conditions are true:

    1. BGP mVPN routing is enabled and a neighbor is configured. The following example shows configuration commands that will be present:
    router bgp
    address-family mvpn
    neighbor
    2. A neighbor session is established.

    Note: For Cisco IOS XR, the only vulnerable configuration is address-family mvpn as noted above. BGP mVPN with MDT is NOT affected.

    A device running Cisco IOS has an affected configuration if BOTH of the following conditions are true:

    1. BGP routing is enabled and a neighbor is configured. The following example shows configuration commands that will be present:
    router bgp
    neighbor
    2. A BGP neighbor session is established.


    You can determine if a BGP session is established using the show ip bgp summary command in Cisco IOS Software. In Cisco IOS XR software, you can determine if a BGP session is established using the show bgp mvpn all summary command. The following example shows the output from an IOS router with two neighbor sessions established:

    Router# show ip bgp summary 

    !--- output shortened

    Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down State/PfxRcd

    10.100.1.1      4   200      26      22      199    0    0 00:14:23 23

    10.200.1.1      4   300      21      51      199    0    0 00:13:40 0


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

    The following example identifies a Cisco product that is running Cisco IOS Software Release 15.0(1)M1 with an installed image name of C3900-UNIVERSALK9-M:

    Router> show version 
    Cisco IOS Software, C3900 Software (C3900-UNIVERSALK9-M), Version 15.0(1)M1, RELEASE SOFTWARE (fc1)
    Technical Support: http://www.cisco.com/techsupport
    Copyright (c) 1986-2009 by Cisco Systems, Inc.
    Compiled Wed 02-Dec-09 17:17 by prod_rel_team
    !--- output truncated

    Additional information about Cisco IOS Software release naming conventions is available in "White Paper: Cisco IOS and NX-OS Software Reference Guide" at http://www.cisco.com/web/about/security/intelligence/ios-ref.html.

    Products Confirmed Not Vulnerable

    A Cisco IOS router is not vulnerable if BGP is not running, or if BGP does not have at least one neighbor session established. No other Cisco products are currently known to be affected by this vulnerability. Cisco NXOS Software is not affected.

    The following example shows output from a router with BGP enabled, two neighbors configured, but with no sessions established with the remote BGP peers:

    Router# show ip bgp summary 

    !--- output shortened

    Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down State/PfxRcd

    10.100.1.1      4   200      0       0        0    0    0 never    Idle

    10.200.1.1      4   300      0       2        0    0    0 never    Idle

Details

  • Cisco IOS Software contains a vulnerability in the BGP routing protocol feature. This vulnerability affects Cisco IOS Software, Cisco IOS-XR Software, and Cisco IOS-XE Software. Cisco NXOS Software is not affected.

    The vulnerability may be triggered when the router receives a malformed attribute from a peer on an existing BGP session. At least one BGP neighbor session must be established for a router to be vulnerable.

    Successful exploitation of this vulnerability may cause all BGP peers to reset. Repeated exploitation may result in an inability to route packets to BGP neighbors during reconvergence times.

    This vulnerability is documented in Cisco bug IDs CSCtt35379 (registered customers only) and CSCty58300 (registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2012-4617. The corresponding Cisco IOS XR Software bug IDs are CSCtz63248 (registered customers only) and CSCtz62914 (registered customers only)

Workarounds

Fixed Software

  • When considering software upgrades, customers are advised to consult the Cisco Security Advisories and Responses archive at http://www.cisco.com/go/psirt and review subsequent advisories to determine exposure and a complete upgrade solution.

    In all cases, customers should ensure that the devices to be upgraded contain sufficient memory and confirm that current hardware and software configurations will continue to be supported properly by the new release. If the information is not clear, customers are advised to contact the Cisco Technical Assistance Center (TAC) or their contracted maintenance providers.

    Cisco IOS Software

    Each row of the following Cisco IOS Software table corresponds to a Cisco IOS Software train. If a particular train is vulnerable, the earliest releases that contain the fix are listed in the First Fixed Release column. The First Fixed Release for All Advisories in the September 2012 Bundled Publication column lists the earliest possible releases that correct all the published vulnerabilities in the Cisco IOS Software Security Advisory bundled publication. Cisco recommends upgrading to the latest available release, where possible.

    The Cisco IOS Software Checker allows customers to search for Cisco Security Advisories that address specific Cisco IOS Software releases. This tool is available on the Cisco Security (SIO) portal at https://sec.cloudapps.cisco.com/security/center/selectIOSVersion.x



    Major Release Availability of Repaired Releases
    Affected 12.0-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2012 Cisco IOS Software Security Advisory Bundled Publication
    There are no affected 12.0 based releases
    Affected 12.2-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2012 Cisco IOS Software Security Advisory Bundled Publication
    There are no affected 12.2 based releases
    Affected 12.3-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2012 Cisco IOS Software Security Advisory Bundled Publication
    There are no affected 12.3 based releases
    Affected 12.4-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2012 Cisco IOS Software Security Advisory Bundled Publication
    There are no affected 12.4 based releases
    Affected 15.0-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2012 Cisco IOS Software Security Advisory Bundled Publication
    There are no affected 15.0 based releases
    Affected 15.1-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2012 Cisco IOS Software Security Advisory Bundled Publication
    There are no affected 15.1 based releases
    Affected 15.2-Based Releases First Fixed Release First Fixed Release for All Advisories in the September 2012 Cisco IOS Software Security Advisory Bundled Publication
    15.2GC Not vulnerable
    		 Releases prior to 15.2(3)GC are vulnerable; Releases 15.2(3)GC and later are not vulnerable. First fixed in Release 15.2T
    15.2JA Not vulnerable
    		 Not Vulnerable
    15.2M Not vulnerable
    Not vulnerable
    15.2S 15.2(1)S0a
    15.2(1)S2

    Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
    		 15.2(1)S2
    15.2(2)S1
    15.2(4)S

    Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
    15.2SNG Not vulnerable
    		 Not vulnerable
    15.2T Not vulnerable
    		 15.2(1)T3
    15.2(2)T2
    15.2(3)T2; Available on 12-OCT-12

    Cisco IOS XE Software

    Cisco IOS XE is affected by the vulnerability described in this advisory.

    Cisco IOS XE Software Release First Fixed Release First Fixed Release for All Advisories in the September 2012 Cisco IOS Software Security Advisory Bundled Publication
    2.1.x Not vulnerable Vulnerable; migrate to 3.6.0S or later.
    2.2.x Not vulnerable Vulnerable; migrate to 3.6.0S or later.
    2.3.x Not vulnerable Vulnerable; migrate to 3.6.0S or later.
    2.4.x Not vulnerable Vulnerable; migrate to 3.6.0S or later.
    2.5.x Not vulnerable Vulnerable; migrate to 3.6.0S or later.
    2.6.x Not vulnerable Vulnerable; migrate to 3.6.0S or later.
    3.1.xS Not vulnerable 3.1.4S
    3.1.xSG Not vulnerable Vulnerable; migrate to 3.2.5SG or later.
    3.2.xS Not vulnerable Vulnerable; migrate to 3.6.0S or later.
    3.2.xSG Not vulnerable 3.2.5SG
    3.2.xSO Not vulnerable Vulnerable; migrate to 3.3.1SG or later.
    3.3.xS Not vulnerable Vulnerable; migrate to 3.6.0S or later.
    3.3xSG Not vulnerable 3.3.1SG
    3.4.xS Not vulnerable Vulnerable; migrate to 3.6.0S or later.
    3.5.xS 3.5.2S Vulnerable; migrate to 3.6.0S or later.
    3.6.xS Not vulnerable Not vulnerable
    3.7xS Not vulnerable Not vulnerable

    Cisco IOS XR Software

    Cisco IOS XR Software Releases 4.1.0, 4.1.1, 4.1.2, 4.2.0, 4.2.1, and 4.2.2 are affected by the vulnerability described in this advisory.


    Release Platform CSCtz62914 SMU ID CSCtz63248 SMU ID
    4.1.0 c12k AA06458 AA06464
    4.1.0 CRS AA06437 AA06399
    4.1.0 asr9k AA06449 AA06444
    4.1.1 c12k AA06459 AA06465
    4.1.1 CRS AA06438 AA06400
    4.1.1 asr9k AA06450 AA06445
    4.1.2 c12k AA06460 AA06466
    4.1.2 CRS AA06439 AA06401
    4.1.2 asr9k AA06451 AA06446
    4.2.0 c12k AA06461 AA06467
    4.2.0 CRS AA06440 AA06402
    4.2.0 asr9k AA06452 AA06447
    4.2.0 asr9k (PX) AA06453 AA06448
    4.2.1 c12k AA06462 AA06546
    4.2.1 CRS AA06441 AA06547
    4.2.1 asr9k AA06454 AA06548
    4.2.1 asr9k (PX) AA06455 AA06549
    4.2.2 asr9k AA06581 AA06550
    4.2.2 asr9k (PX) AA06582 AA06551


Exploitation and Public Announcements

  • The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.

    This vulnerability was found internally by Cisco during testing.

Cisco Security Vulnerability Policy

  • To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.

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Revision History

  • Revision 1.1 2012-October-04 Added mVPN MDT note in the "Vulnerable Products" section.
    Revision 1.0 2012-September-26 Initial public release
    Show Less

Cisco Security Vulnerability Policy

  • To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.

Subscribe to Cisco Security Notifications

Action Links for This Advisory

Related to This Advisory