Summary

• A vulnerability in the Resource Reservation Protocol (RSVP) feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to trigger an interface queue wedge on the affected device.
  
  The vulnerability is due to improper parsing of UDP RSVP packets. An attacker could exploit this vulnerability by sending UDP port 1698 RSVP packets to the vulnerable device. An exploit could cause Cisco IOS Software and Cisco IOS XE Software to incorrectly process incoming packets, resulting in an interface queue wedge, which can lead to loss of connectivity, loss of routing protocol adjacency, and other denial of service (DoS) conditions.
   
  Cisco has released software updates that address this vulnerability.
  
  Workarounds that mitigate this vulnerability are available.
  
  This advisory is available at the following link: 
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20130925-rsvp
  

  Note: The September 25, 2013, Cisco IOS Software Security Advisory bundled publication includes eight Cisco Security Advisories. All advisories address vulnerabilities in Cisco IOS Software. 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 2013 bundled publication.

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

  http://www.cisco.com/web/about/security/intelligence/Cisco_ERP_sep13.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 have RSVP enabled and also have one or more virtual routing and forwarding (VRF) interfaces. A device is vulnerable if both of the following criteria are met:

  • At least one VRF instance is configured without RSVP
  • At least one other interface (physical or virtual), not in the same VRF (or is in the global table), has RSVP enabled

  Some example scenarios are as follows:

  • RSVP-Traffic Engineering (RSVP-TE) in Multiprotocol Label Switching (MPLS) infrastructures
  • Multi-VRF infrastructures
  • VRF-Lite infrastructures
  • Cisco 7600 with MPLS enabled

  To determine weather a device is enabled with RSVP, the best method is to use the show ip rsvp command-line interface exec (CLI) command. If the device is not configured with RSVP, the output will indicate that RSVP is disabled and is not enabled on any interface as shown in the following example:
  

  Router#show ip rsvp
  RSVP: disabled (not enabled on any interface)

  If the device is configured with RSVP the output will indicate that RSVP is enabled as shown in the following example:
  

  Router#show ip rsvp
  RSVP: enabled (on 1 interface(s))

  Note: Cisco 7600 Software images will enable RSVP on an internal VLAN context when MPLS is enabled on the device.
  
  Only traffic directed to the device will trigger the vulnerability. Transit traffic will not trigger the vulnerability.  Because this vulnerability can be exploited using UDP packets, the source of the packets may be spoofed.
  

  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.
  
  Cisco IOS NX-OS Software is not affected by this vulnerability.
  
  No other Cisco products are currently known to be affected by this vulnerability.

Details

• A vulnerability in the RSVP feature of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to trigger an interface queue wedge on the affected device.
  
  The vulnerability is due to improper parsing of UDP RSVP packets. An attacker could exploit this vulnerability by sending UDP RSVP packets to the vulnerable device. An exploit could cause Cisco IOS Software and Cisco IOS XE Software to incorrectly process incoming packets, resulting in an interface queue wedge, which can lead to loss of connectivity, loss of routing protocol adjacency, and other DoS conditions.
  
  In devices that meet the vulnerable configuration criteria, valid UDP 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.
  
  This vulnerability can be exploited using both RSVP over UDP over IPv4 and RSVP over UDP over IPv6 on UDP port 1698.   Exploitation with UDP over IPv6 affects only Cisco IOS Software releases 15.2(3)T, 15.2(4)M, and later only. 
  
  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. Consult the Workarounds section of this advisory for more information about queue wedges and some detection mechanisms that may be used to identify a blocked interface on Cisco IOS Software. Also see the Cisco Security Blog "Cisco IOS Queue Wedges Explained" at the following link: http://blogs.cisco.com/security/cisco_ios_queue_wedges_explained/
  
  This vulnerability has been documented in Cisco Bug ID CSCuf17023 (registered customers only) and has been assigned the Common Vulnerabilities and Exposures (CVE) ID CVE-2013-5478.
  

Workarounds

• The following identification mechanisms exist for this vulnerability:
  
  Embedded Event Manager
  
  A Cisco IOS Embedded Event Manager (EEM) policy that is based on Tool Command Language (Tcl) can be used on vulnerable Cisco IOS devices to identify and detect an interface queue wedge that is caused by this vulnerability. The policy allows administrators to monitor the interfaces for Cisco IOS device and detect when the interface input queues are full. When Cisco IOS EEM detects potential exploitation of this vulnerability, the policy can trigger a response by sending an alert to the network administrator, who could then decide to implement an upgrade, implement suitable mitigations or reload the device to clear the input queue.
  
  The Tcl script is available for download at the "Cisco Beyond: Embedded Event Manager (EEM) Scripting Community" at the following link: https://supportforums.cisco.com/docs/DOC-19337
  
  Also see the Cisco Security Blog "Cisco IOS Queue Wedges Explained" at the following link: http://blogs.cisco.com/security/cisco_ios_queue_wedges_explained/
  
  The following mitigations exist for this vulnerability:
  
  IP RSVP Listener
  
  It is possible to mitigate this vulnerability under affected configurations by applying the global configuration command ip rsvp listener vrf vrf-name ip-address udp 1698 announce, where the IP address is one that does not exist on the device or in the routing tables.
  
  Infrastructure Access Control Lists (iACL) and Unicast Reverse Path Forwarding (uRPF)
  
  Because the feature in this vulnerability utilizes UDP as a transport, it is possible to spoof the sender's IP address, which may defeat ACLs that permit communication to these ports from trusted IP addresses. In addition to ACLs, administrators should enable uRPF, a security feature of Cisco IOS Software that verifies the reachability of the source address in packets being forwarded. The combination of these two technologies offers a stronger migration than iACLs alone.
  
  Although it is often difficult to block traffic that transits a network, it is possible to identify traffic that should never be allowed to target infrastructure devices and block that traffic at the border of networks. Infrastructure ACLs (iACLs) are 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 iACL example below should be included as part of the deployed infrastructure access-list, which will help protect all devices with IP addresses in the infrastructure IP address range:

  
  !---!--- Feature: RSVP over UDP!---
  
  access-list 150 permit udp TRUSTED_SOURCE_ADDRESSES WILDCARD 
      INFRASTRUCTURE_ADDRESSES WILDCARD eq 1698
  
  !--- Deny RSVP over UDP traffic from all other sources destined !--- to infrastructure addresses.
  
  access-list 150 deny udp any 
      INFRASTRUCTURE_ADDRESSES WILDCARD eq 1698
  
  !--- Permit/deny all other Layer 3 and Layer 4 traffic in !--- accordance with existing security policies and !--- configurations. Permit all other traffic to transit the!--- device.
  
  access-list 150 permit ip any any
  
  !--- Apply access-list to all interfaces (only one example!--- shown)
  
  interface fastEthernet 2/0
   ip access-group 150 in

  The white paper entitled "Protecting Your Core: Infrastructure Protection Access Control Lists" presents guidelines and recommended deployment techniques for infrastructure protection access lists and is available at the following link http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801a1a55.shtml
  
  Control Plane Policing
  
  Warning: Because the feature in this vulnerability utilizes UDP as a transport, it is possible to spoof the sender's IP address, which may defeat ACLs that permit communication to these ports from trusted IP addresses. Unicast RPF should be considered to be used in conjunction to offer a better mitigation solution.
  
  Control Plane Policing (CoPP) can be used to block untrusted UDP traffic to the device. Cisco IOS software releases 12.0S, 12.2SX, 12.2S, 12.3T, 12.4, and 12.4T support the CoPP feature. CoPP can be configured on a device to help protect the management and control planes and minimize the risk and effectiveness of direct infrastructure attacks by explicitly permitting only authorized traffic that is sent to infrastructure devices in accordance with existing security policies and configurations. The CoPP example below should be included as part of the deployed CoPP, which will help protect all devices with IP addresses in the infrastructure IP address range.

  !--- Feature: RSVP over UDP
  
  access-list 150 deny udp TRUSTED_SOURCE_ADDRESSES WILDCARD
       any eq 1698
  
  !--- Deny RSVP over UDP traffic from all other sources destined !--- to the device control plane.
  
  access-list 150 permit udp any any eq 1698
  
  !--- Permit (Police or Drop)/Deny (Allow) all other Layer3 and !--- Layer4 traffic in accordance with existing security policies !--- and configurations for traffic that is authorized to be sent !--- to infrastructure devices !--- Create a Class-Map for traffic to be policed by!--- the CoPP feature
  
  class-map match-all drop-udp-class
   match access-group 150
  
  !--- Create a Policy-Map that will be applied to the !--- Control-Plane of the device.
  
  policy-map drop-udp-traffic
   class drop-udp-class
    drop
  
  !--- Apply the Policy-Map to the !--- Control-Plane of the device
  
  control-plane
   service-policy input drop-udp-traffic

  In the above CoPP example, the access control list entries (ACEs) that match the potential exploit packets with the "permit" action result in these packets being discarded by the policy-map "drop" function, while packets that match the "deny" action (not shown) are not affected by the policy-map drop function. Please note that the policy-map syntax is different in the 12.2S and 12.0S Cisco IOS software trains:

  policy-map drop-udp-traffic
  class drop-udp-class
  police 32000 1500 1500 conform-action drop exceed-action drop

  Additional information on the configuration and use of the CoPP feature can be found in the documents, "Control Plane Policing Implementation Best Practices" and "Control Plane Policing" at the following links: http://www.cisco.com/web/about/security/intelligence/coppwp_gs.html and http://www.cisco.com/en/US/docs/ios/12_4t/12_4t4/htcpp.html

Fixed Software

• When considering software upgrades, customers are advised to consult the Cisco Security Advisories, Responses, and Notices 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 2013 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 2013 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 2013 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 2013 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 2013 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 2013 Cisco IOS Software Security Advisory Bundled Publication
  15.0EA	Not vulnerable	15.0(2)EA1
  15.0EB	Not vulnerable	Vulnerable; migrate to any release in 15.2E
  15.0EC	Not vulnerable	Vulnerable; migrate to any release in 15.2E
  15.0ED	Not vulnerable	Note: Releases prior to 15.0(2)ED1 are vulnerable; Releases 15.0(2)ED1 and later are not vulnerable.
  15.0EH	Not vulnerable	Not vulnerable
  15.0EJ	Not vulnerable	Not vulnerable
  15.0EX	Cisco IOS XE devices: Please see Cisco IOS XE Software Availability	Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
  15.0EY	Not vulnerable	15.0(2)EY2
  15.0EZ	Not vulnerable	Only Release 15.0(2)EZ is vulnerable
  15.0M	Vulnerable; First fixed in Release 15.1M	Vulnerable; First fixed in Release 15.1M
  15.0MR	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	Vulnerable; First fixed in Release 15.1S Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
  15.0SE	Not vulnerable	15.0(2)SE4
  15.0SG	Not vulnerable Cisco IOS XE devices: Please see Cisco IOS XE Software Availability	Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory. Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
  15.0SQA	Cisco IOS XE devices: Please see Cisco IOS XE Software Availability	Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
  15.0SQB	Cisco IOS XE devices: Please see Cisco IOS XE Software Availability	Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
  15.0SY	15.0(1)SY5	15.0(1)SY5
  15.0XA	Vulnerable; First fixed in Release 15.1M	Vulnerable; First fixed in Release 15.1M
  15.0XO	Not vulnerable 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 September 2013 Cisco IOS Software Security Advisory Bundled Publication
  15.1EY	Vulnerable; First fixed in Release 15.2S	Vulnerable; First fixed in Release 15.2S
  15.1GC	Vulnerable; First fixed in Release 15.1M	Vulnerable; First fixed in Release 15.1M
  15.1M	15.1(4)M7	15.1(4)M7
  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.
  15.1MRA	15.1(3)MRA2	15.1(3)MRA2
  15.1S	15.1(3)S6 Cisco IOS XE devices: Please see Cisco IOS XE Software Availability	15.1(3)S6 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	15.1(2)SG1 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	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.
  15.1SNI	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.
  15.1SVD	Not vulnerable	Not vulnerable
  15.1SVE	Not vulnerable	Not vulnerable
  15.1SVF	Not vulnerable	Not vulnerable
  15.1SY	15.1(1)SY2; Available on 28-OCT-13 15.1(2)SY	15.1(1)SY2; Available on 28-OCT-13 15.1(2)SY
  15.1T	Vulnerable; First fixed in Release 15.1M	Vulnerable; First fixed in Release 15.1M
  15.1XO	Not vulnerable	Not vulnerable
  Affected 15.2-Based Releases	First Fixed Release	First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
  15.2E	Not vulnerable	Not vulnerable
  15.2GC	15.2(4)GC	Vulnerable; migrate to any release in 15.4T
  15.2JA	Not vulnerable	15.2(4)JA1
  15.2JAX	Not vulnerable	Vulnerable; contact your support organization per the instructions in Obtaining Fixed Software section of this advisory.
  15.2JB	Not vulnerable	15.2(2)JB2
  15.2JN	Not vulnerable	Not vulnerable
  15.2M	15.2(4)M4	15.2(4)M4
  15.2S	15.2(4)S4	15.2(4)S4 Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
  15.2SA	15.2(2)SA	15.2(2)SA
  15.2SNG	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.
  15.2SNH	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.
  15.2SNI	Vulnerable; First fixed in Release 15.3S	Vulnerable; First fixed in Release 15.3S
  15.2T	15.2(2)T4 15.2(3)T4	15.2(3)T4
  Affected 15.3-Based Releases	First Fixed Release	First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
  15.3M	Not vulnerable	Not vulnerable
  15.3S	15.3(2)S 15.3(3)S Cisco IOS XE devices: Please see Cisco IOS XE Software Availability	15.3(2)S2 15.3(3)S Cisco IOS XE devices: Please see Cisco IOS XE Software Availability
  15.3T	15.3(1)T2 15.3(2)T1	15.3(1)T2 15.3(2)T1

  
  

   

  Cisco IOS XE Software

  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 XE Software Release	First Fixed Release	First Fixed Release for All Advisories in the September 2013 Cisco IOS Software Security Advisory Bundled Publication
  2.1.x	Not vulnerable	Vulnerable; migrate to 3.4.6S or later.
  2.2.x	Not vulnerable	Vulnerable; migrate to 3.4.6S or later.
  2.3.x	Not vulnerable	Vulnerable; migrate to 3.4.6S or later.
  2.4.x	Not vulnerable	Vulnerable; migrate to 3.4.6S or later.
  2.5.x	Not vulnerable	Vulnerable; migrate to 3.4.6S or later.
  2.6.x	Not vulnerable	Vulnerable; migrate to 3.4.6S or later.
  3.1.xS	Not vulnerable	Vulnerable; migrate to 3.4.6S or later.
  3.1.xSG	Not vulnerable	Vulnerable; contact your support organization.
  3.2.xS	Vulnerable; migrate to 3.4.6S or later.	Vulnerable; migrate to 3.4.6S or later.
  3.2.xSE	Not vulnerable	3.2.3SE
  3.2.xSG	Not vulnerable	Vulnerable; migrate to 3.4.1SG or later.
  3.2.xXO	Not vulnerable	Vulnerable; migrate to 3.3.0XO or later.
  3.2.xSQ	Not vulnerable	Vulnerable; migrate to 3.3.0SQ or later.
  3.3.xS	Vulnerable; migrate to 3.4.6S or later.	Vulnerable; migrate to 3.4.6S or later.
  3.3xSG	Not vulnerable	Vulnerable; migrate to 3.4.1SG or later.
  3.3xXO	Not vulnerable	Not vulnerable
  3.3xSQ	Not vulnerable	Not vulnerable
  3.4.xS	3.4.6S	3.4.6S
  3.4.xSG	Not vulnerable	3.4.1SG *
  3.5.xE	Not vulnerable	Not vulnerable
  3.5.xS	Vulnerable; migrate to 3.7.4S or later.	Vulnerable; migrate to 3.7.4S or later.
  3.6.xS	Vulnerable; migrate to 3.7.4S or later.	Vulnerable; migrate to 3.7.4S or later.
  3.7.xS	3.7.4S	3.7.4S
  3.8.xS	Vulnerable; migrate to 3.9.0S or later.	Vulnerable; migrate to 3.9.2S or later.
  3.9.xS	Not vulnerable	3.9.2S
  3.10.xS	Not vulnerable	Not vulnerable

  
  * Cisco Catalyst 4500 Series Switches with Cisco Catalyst 4500 Supervisor Engines 7-E and 7L-E and Cisco Catalyst 4500-X Series Switches can migrate to Cisco IOS XE Software Release 3.4SG.
  

  Cisco IOS XR Software

  Cisco IOS XR Software is not affected by any of the vulnerabilities that are disclosed in the September 2013 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 security testing.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20130925-rsvp

Revision History

• Revision 1.1	2014-March-12	Added additional details in "Affected Products" section to help determine if RSVP is enabled.
  Revision 1.0	2013-September-25	Initial public release

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