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Cisco IOS XR Software IPv6 Malformed Packet Denial of Service Vulnerability

Advisory ID: cisco-sa-20140611-ipv6

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20140611-ipv6

Revision 1.1

Last Updated  2014 June 13 14:01  UTC (GMT)

For Public Release 2014 June 11 16:00  UTC (GMT)


Summary


A vulnerability in the parsing of malformed Internet Protocol version 6 (IPv6) packets in Cisco IOS XR Software for ASR 9000 Series Aggregation Services Routers could allow an unauthenticated, remote attacker to cause a lockup and eventual reload of a Network Processor (NP) chip and a line card processing traffic. Only Trident-based line cards on Cisco ASR 9000 Series Aggregation Services Routers are affected by this vulnerability.

The vulnerability is due to insufficient logic in parsing malformed IPv6 packets. An attacker could exploit this vulnerability by sending a stream of malformed IPv6 packets to the affected device. An exploit could allow the attacker to cause a lockup and eventual reload of an NP chip and a line card, leading to a denial of service (DoS) condition.


Cisco has released free software updates that address this vulnerability.
There are no workarounds that address this vulnerability.

This advisory is available at the following link:
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20140611-ipv6

Affected Products

Vulnerable Products


Cisco ASR 9000 Series Routers with Trident-based line cards are affected by this vulnerability. The device does not have to be configured with IPv6 to be affected by this vulnerability.

The first generation of the Cisco ASR 9000 Series Ethernet line cards are referred to as Trident-based line cards. The term comes from the NPs that are used on these line cards.

The following line cards are Trident based:

  • A9K-40GE-L
  • A9K-40GE-B
  • A9K-40GE-E
  • A9K-4T-L
  • A9K-4T-B
  • A9K-4T-E
  • A9K-8T/4-L
  • A9K-8T/4-B
  • A9K-8T/4-E
  • A9K-2T20GE-L
  • A9K-2T20GE-B
  • A9K-2T20GE-E
  • A9K-8T-L
  • A9K-8T-B
  • A9K-8T-E
  • A9K-16T/8-B

To determine whether the line card on an ASR 9000 Series Router is Trident based, the administrator can use the show diag command. Affected devices will include the PID for at least one of the Trident-based cards. The following example shows the device on which an A9K-40GE-B card is active:

RP/0/RSP0/CPU0:router(admin)# show diag

Mon Jun 22 12:55:10.554 PST

NODE module 0/RSP0/CPU0 : 

  MAIN:  board type 0x100302

!--- output truncated

NODE module 0/1/CPU0 :  

   MAIN:  board type 0x20207
  S/N:   FOC123081J6
  Top Assy. Number:   68-3182-03
  PID:   A9K-40GE-B
  UDI_VID:   V1D
  HwRev: V0.0
  New Deviation Number: 0
  CLEI:   
  Board State : IOS XR RUN
  PLD:    Motherboard: N/A, Processor: 0x8004 (rev: 2.2), Power: N/A
  ROMMON: Version 1.0(20081208:174521) [ASR9K ROMMON]

!--- output truncated


Products Confirmed Not Vulnerable


Cisco ASR 9000 Series Routers with Typhoon-based line cards are not affected by this vulnerability. 
The second generation of the ASR 9000 Series Ethernet line cards are often referred to as Typhoon-based line cards.

These line cards are Typhoon based:

  • A9K-MOD80-SE
  • A9K-MOD80-TR
  • A9K-MOD160-SE
  • A9K-MOD160-TR
  • A9K-24X10GE-SE
  • A9K-24X10GE-TR
  • A9K-36X10GE-SE
  • A9K-36X10GE-TR
  • A9K-2X100GE-SE
  • A9K-2X100GE-TR
  • A9K-1X100GE-SE
  • A9K-1X100GE-TR

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

Details

A vulnerability in the parsing of malformed Internet Protocol version 6 (IPv6) packets in Cisco IOS XR Software for ASR 9000 Series Aggregation Services Routers could allow an unauthenticated, remote attacker to cause a lockup and eventual reload of a Network Processor (NP) chip and a line card processing traffic. Only Trident-based line cards on Cisco ASR 9000 Series Aggregation Services Routers are affected by this vulnerability.

The vulnerability is due to insufficient logic in parsing malformed IPv6 packets. An attacker could exploit this vulnerability by sending a stream of malformed IPv6 packets to the affected device. An exploit could allow the attacker to cause a lockup and eventual reload of an NP chip and a line card, leading to a denial of service (DoS) condition.

This vulnerability could be exploited repeatedly to cause an extended DoS condition.

A device does not need to be configured for IPv6 functionality to be affected by this vulnerability. If interfaces on the Trident-based line card do not have IPv6 functionality enabled, the attacker can only send malformed traffic from an adjacent host. If a device has IPv6 functionality enabled, the vulnerability can be exploited from a remote network.

While certain intermediate devices may block malformed IPv6 packets, the possibility still exists for a malformed packet to originate from a remote network and exploit this vulnerability on an affected device.

This vulnerability has been documented in Cisco bug ID CSCun71928 (registered customers only) and has been assigned the Common Vulnerabilities and Exposures (CVE) CVE-2014-2176.


Vulnerability Scoring Details

Cisco has scored the vulnerability in this advisory based on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this security advisory is in accordance with CVSS version 2.0.

CVSS is a standards-based scoring method that conveys vulnerability severity and helps organizations determine the urgency and priority of a response.

Cisco has provided a base and temporal score. Customers can also compute environmental scores that help determine the impact of the vulnerability in their own networks.

Cisco has provided additional information regarding CVSS at the following link:

http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html

Cisco has also provided a CVSS calculator to compute the environmental impact for individual networks at the following link:

http://intellishield.cisco.com/security/alertmanager/cvss



CSCun71928 - Cisco IOS XR Software IPv6 Malformed Packet Denial of Service Vulnerability

Calculate the environmental score of CSCun71928

CVSS Base Score - 7.1

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Medium

None

None

None

Complete

CVSS Temporal Score - 5.9

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed


Impact

Successful exploitation of this vulnerability could cause a lockup and eventual reload of an NP chip and the affected line card.

All traffic passing through that card will be affected by this condition.

Software Versions and Fixes

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.

This vulnerability is corrected in the following Cisco IOS XR Software SMUs:

  • asr9k-p-4.1.2.CSCun71928 for version 4.1.2
  • asr9k-p-4.2.1.CSCun71928 and asr9k-px-4.2.1.CSCun71928 for version 4.2.1
  • asr9k-px-4.2.3.CSCun71928 and asr9k-p-4.2.3.CSCun71928 for version 4.2.3
  • asr9k-px-4.3.1.CSCun71928 for version 4.3.1
  • asr9k-px-4.3.2.CSCun71928 for version 4.3.2
  • asr9k-px-4.3.4.CSCuo22306 for version 4.3.4
  • asr9k-px-5.1.1.CSCuo22306 for version 5.1.1

Cisco IOS XR Software Release 5.1.2 is not affected by this vulnerability.

Note: Cisco IOS XR Software SMUs for additional versions will be published when available.

Workarounds

There are no workarounds for this vulnerability.

Additional mitigations that can be deployed on Cisco devices within the network are available in the companion document Identifying and Mitigating Exploitation of the Cisco IOS XR Software IPv6 Malformed Packet Denial of Service Vulnerability, which is available at the following link: http://tools.cisco.com/security/center/viewAMBAlert.x?alertId=33986

Obtaining Fixed Software

Cisco has released free software updates that address the vulnerability described in this advisory. Prior to deploying software, customers are advised to consult their maintenance providers or check the software for feature set compatibility and known issues that are specific to their environments.

Customers may only install and expect support for feature sets they have purchased. By installing, downloading, accessing, or otherwise using such software upgrades, customers agree to follow the terms of the Cisco software license at http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.html.

Customers with Service Contracts

Customers with contracts should obtain upgraded software through their regular update channels. For most customers, upgrades should be obtained through the Software Navigator on Cisco.com at http://www.cisco.com/cisco/software/navigator.html.

Customers using Third Party Support Organizations

Customers with Cisco products that are provided or maintained through prior or existing agreements with third-party support organizations, such as Cisco Partners, authorized resellers, or service providers, should contact that organization for assistance with the appropriate course of action.

The effectiveness of any workaround or fix depends on specific customer situations, such as product mix, network topology, traffic behavior, and organizational mission. Because of the variety of affected products and releases, customers should consult their service providers or support organizations to ensure that any applied workaround or fix is the most appropriate in the intended network before it is deployed.

Customers without Service Contracts

Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco Technical Assistance Center (TAC):

  • +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

Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade. Customers without service contracts should request free upgrades through the TAC.

Refer to Cisco Worldwide Contacts at http://www.cisco.com/en/US/support/tsd_cisco_worldwide_contacts.html for additional TAC contact information, including localized telephone numbers, instructions, and e-mail addresses for support in various languages.

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 TAC during the investigation of customer cases.


Status of this Notice: Final

THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.

A stand-alone copy or Paraphrase of the text of this document that omits the distribution URL in the following section is an uncontrolled copy, and may lack important information or contain factual errors.


Distribution

This advisory is posted on Cisco Security at the following link:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20140611-ipv6

Additionally, a text version of this advisory is clear signed with the Cisco PSIRT PGP key and circulated among the following e-mail addresses:

  • cust-security-announce@cisco.com
  • first-bulletins@lists.first.org
  • bugtraq@securityfocus.com
  • vulnwatch@vulnwatch.org
  • cisco@spot.colorado.edu
  • cisco-nsp@puck.nether.net
  • full-disclosure@lists.grok.org.uk

Future updates of this advisory, if any, will reside on Cisco.com but may not be announced on mailing lists. Users can monitor this advisory's URL for any updates.


Revision History

Revision 1.1 2014-June-13 Added information about 4.1.2-based SMU to the "Software Versions and Fixes" section.
Revision 1.0 2014-June-11 Initial public release.

Cisco Security Procedures

Complete information about reporting security vulnerabilities in Cisco products, obtaining assistance with security incidents, and registering to receive security information from Cisco is available on Cisco.com at http://www.cisco.com/web/about/security/psirt/security_vulnerability_policy.html. This web page includes instructions for press inquiries regarding Cisco Security Advisories. All Cisco Security Advisories are available at http://www.cisco.com/go/psirt.