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Cisco Security Advisory

Cisco IOS Software RSVP Denial of Service Vulnerability

High
Advisory ID:
cisco-sa-20120328-rsvp
First Published:
2012 March 28 16:00 GMT
Version 1.0:
Final
Workarounds:
See below
Cisco Bug IDs:
CSCts80643
CVE-2012-1311
CVSS Score:
Base 7.8, Temporal 6.4Click Icon to Copy Verbose Score
AV:N/AC:L/Au:N/C:N/I:N/A:C/E:F/RL:OF/RC:C
CVE-2012-1311

Summary

  • Cisco IOS Software and Cisco IOS XE Software contain a vulnerability in the RSVP feature when used on a device configured with VPN routing and forwarding (VRF) instances. This vulnerability could allow an unauthenticated, remote attacker to cause an interface wedge, which can lead to loss of connectivity, loss of routing protocol adjacency, and other denial of service (DoS) conditions. This vulnerability could be exploited repeatedly to cause an extended DoS condition.

    A workaround is available to mitigate this vulnerability.

    Cisco has released software updates that address this vulnerability. This advisory is available at the following link: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120328-rsvp

    Note: The March 28, 2012, Cisco IOS Software Security Advisory bundled publication includes nine Cisco Security Advisories. Each 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 vulnerabilities in the March 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_mar12.html


Affected Products


  • Vulnerable Products

    Only devices with specific configurations are affected. Cisco devices that are running affected Cisco IOS Software or Cisco IOS XE Software versions are vulnerable when they are configured with RSVP and also have one or more VRF interfaces. A device is vulnerable if both the following criteria are met:

    • At least one VRF is configured without RSVP
    • At least one other interface (physical or virtual), not in the same VRF, is configured with RSVP

    Some example scenarios are as follows:

    • RSVP-Traffic Engineering (RSVP-TE) in Multiprotocol Label Switching (MPLS) infrastructures
    • Multi-VRF infrastructures
    • VRF-Lite infrastructures

    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

    Cisco IOS-XR software is not affected by this vulnerability.

    No other Cisco products are currently known to be affected by this vulnerability.

Details

  • Cisco IOS Software and Cisco IOS XE Software contain a vulnerability in the RSVP feature when used on a device configured with VPN routing and forwarding (VRF) instances. This vulnerability could allow an unauthenticated, remote attacker to cause an interface wedge, which can lead to loss of connectivity, loss of routing protocol adjacency, and other denial of service (DoS) conditions. This vulnerability could be exploited repeatedly to cause an extended DoS condition.

    A device is vulnerable if it is configured with VRF and none of the interfaces in that VRF have RSVP enabled, but any other interface (physical or virtual) does have RSVP enabled.

    An attacker with some knowledge of the affected infrastructure could exploit this vulnerability by sending RSVP packets to vulnerable devices. Successful exploitation of the vulnerability could allow an attacker to wedge the receive queue of any RSVP ingress interface.

    A workaround is available to mitigate this vulnerability.

    In devices that meet the vulnerable configuration criteria, valid RSVP packets could trigger this vulnerability. An attacker with knowledge of the infrastructure could craft valid RSVP packets with set conditions to exploit this vulnerability. Recovery from this interface queue wedge requires a reload of the device.

    An interface queue wedge is a class of vulnerability in which certain packets are received and queued by a Cisco IOS router or switch but, due to a processing error, are never removed from the queue.

    For more information about queue wedges and a few detection mechanisms that may be used to identify a blocked interface on Cisco IOS Software (including a white paper describing how this condition can be detected using SNMP) see http://blogs.cisco.com/security/comments/cisco_ios_queue_wedges_explained/.

    This vulnerability has been documented in Cisco bug ID CSCts80643 (registered customers only) and has been assigned the Common Vulnerabilities and Exposures (CVE) ID CVE-2012-1311.

Workarounds

  • It is possible to mitigate the vulnerability in this advisory by applying the global configuration command ip rsvp listener vrf vrf-name ip-address 0 0 announce, where the IP address is one that does not exist on the device or in the routing tables.

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 March 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 March 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 March 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 March 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 March 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 March 2012 Cisco IOS Software Security Advisory Bundled Publication
    15.0M 15.0(1)M8
    		 15.0(1)M8
    15.0MR Not vulnerable
    		 Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
    15.0MRA Not vulnerable
    		 Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
    15.0S Not vulnerable
    Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
    		 15.0(1)S5
    Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
    15.0SA Not vulnerable
    		 Not vulnerable
    15.0SE Not vulnerable
    		 15.0(1)SE1
    15.0SG Not vulnerable
    Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
    		 15.0(2)SG2
    Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
    15.0SY 15.0(1)SY1
    		 15.0(1)SY1
    15.0XA Vulnerable; First fixed in Release 15.1T
    		 Vulnerable; First fixed in Release 15.1T
    15.0XO Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
    		 Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
    Affected 15.1-Based Releases First Fixed Release First Fixed Release for All Advisories in the March 2012 Cisco IOS Software Security Advisory Bundled Publication
    15.1EY 15.1(2)EY2
    		 15.1(2)EY2
    15.1GC 15.1(2)GC2
    		 15.1(2)GC2
    15.1M 15.1(4)M3
    15.1(4)M3a
    		 15.1(4)M4; Available on 30-MAR-12
    15.1MR Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
    		 Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
    15.1S 15.1(3)S2
    Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
    		 15.1(3)S2
    Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
    15.1SG Not vulnerable
    Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
    		 Not vulnerable
    Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
    15.1SNG Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
    		 Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
    15.1SNH Not vulnerable
    		 Not vulnerable
    15.1T 15.1(1)T5; Available on 18-MAY-12
    15.1(2)T5; Available on 27-APR-12
    15.1(3)T3
    		 15.1(3)T3
    15.1XB Vulnerable; First fixed in Release 15.1T
    		 Vulnerable; First fixed in Release 15.1T
    Affected 15.2-Based Releases First Fixed Release First Fixed Release for All Advisories in the March 2012 Cisco IOS Software Security Advisory Bundled Publication
    There are no affected 15.2 based releases

    Cisco IOS XE Software

    Cisco IOS XE Software is affected by the vulnerability that is disclosed in this document.

    Cisco IOS XE Software Release First Fixed Release First Fixed Release for All Advisories in the March 2012 Cisco IOS Software Security Advisory Bundled Publication
    2.1.x Not vulnerable Vulnerable; migrate to 3.4.2S or later.
    2.2.x Not vulnerable Vulnerable; migrate to 3.4.2S or later.
    2.3.x Not vulnerable Vulnerable; migrate to 3.4.2S or later.
    2.4.x Not vulnerable Vulnerable; migrate to 3.4.2S or later.
    2.5.x Not vulnerable Vulnerable; migrate to 3.4.2S or later.
    2.6.x Not vulnerable Vulnerable; migrate to 3.4.2S or later.
    3.1.xS Not vulnerable Vulnerable; migrate to 3.4.2S or later.
    3.1xSG Not vulnerable Vulnerable; migrate to 3.2.2SG or later.
    3.2.xS Vulnerable; migrate to 3.4.2S or later. Vulnerable; migrate to 3.4.2S or later.
    3.2xSG Not vulnerable 3.2.2SG
    3.3.xS Vulnerable; migrate to 3.4.2S or later. Vulnerable; migrate to 3.4.2S or later.
    3.3.xSG Not Vulnerable Not Vulnerable
    3.4.xS 3.4.2S 3.4.2S
    3.5.xS Not vulnerable 3.5.1S
    3.6.xS Not vulnerable Not vulnerable

    For a mapping of Cisco IOS XE Software releases to Cisco IOS Software releases, refer to Cisco IOS XE 2 Release Notes, Cisco IOS XE 3S Release Notes, and Cisco IOS XE 3SG Release Notes.

    Cisco IOS XR Software

    Cisco IOS XR Software is not affected by any of the vulnerabilities disclosed in the March 2012 Cisco IOS Software Security Advisory Bundled Publication.

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 discovered by Cisco during internal 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 1.0 2012-March-28 Initial public release
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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

Related to This Advisory