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Cisco ASR 9000 Series Routers Line Card IP Version 4 Denial of Service Vulnerability

Advisory ID: cisco-sa-20110720-asr9k

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110720-asr9k

Revision 1.0

For Public Release 2011 July 20 16:00  UTC (GMT)


Summary

Cisco 9000 Series Aggregation Services Routers (ASR) running Cisco IOS XR Software version 4.1.0 contain a vulnerability that may cause a network processor in a line card to lock up while processing an IP version 4 (IPv4) packet. As a consequence of the network processor lockup, the line card that is processing the offending packet will automatically reload.

Cisco has released a free software maintenance upgrade (SMU) to address this vulnerability.

There are no workarounds for this vulnerability.

This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110720-asr9k.

Affected Products

Vulnerable Products

This vulnerability affects the following Cisco ASR 9000 Series devices when they are running Cisco IOS XR Software version 4.1.0 without the SMU asr9k-p-4.1.0.CSCtr26695.tar installed:

  • Cisco ASR 9006 router
  • Cisco ASR 9010 router

To determine the software running on a Cisco ASR 9000 Series device, log in to the device and issue the show version brief command to display the system banner. The system banner confirms that the device is running Cisco IOS XR Software by displaying text similar to Cisco IOS XR Software. The software version is displayed after the text Cisco IOS XR Software.

The following example identifies a Cisco ASR 9010 that is running Cisco IOS XR Software Release 4.1.0:

RP/0/0/CPU0:Router#show version brief
Fri Jul  8 18:54:39.222 CEST

Cisco IOS XR Software, Version 4.1.0[Default]
Copyright (c) 2011 by Cisco Systems, Inc.


ROM: System Bootstrap, Version 1.05(20101118:025914) [ASR9K ROMMON],

Router uptime is 9 weeks, 1 day, 5 hours, 53 minutes
System image file is "bootflash:disk0/asr9k-os-mbi-4.1.0/mbiasr9k-rp.vm"

cisco ASR9K Series (MPC8641D) processor with 4194304K bytes of memory.
MPC8641D processor at 1333MHz, Revision 2.2
ASR-9010-CHASSIS

4 Management Ethernet
8 WANPHY controller(s)
8 TenGigE
8 DWDM controller(s)
40 GigabitEthernet
4 SONET/SDH
2 Packet over SONET/SDH
1 MgmtMultilink
219k bytes of non-volatile configuration memory.
975M bytes of compact flash card.
33994M bytes of hard disk.
1605616k bytes of disk0: (Sector size 512 bytes).
1605616k bytes of disk1: (Sector size 512 bytes).

To determine which SMUs are active on the device, issue the show install active summary command. This command will return a list of all SMUs installed, as shown in the following example:

RP/0/0/CPU0:Router#show install active summary
Fri Jul  8 19:02:15.887 CEST
  Active Packages:
    disk0:asr9k-doc-p-4.1.0
    disk0:asr9k-mini-p-4.1.0
    disk0:asr9k-k9sec-p-4.1.0
    disk0:asr9k-video-p-4.1.0

Note: The preceding output shows a device without the SMU asr9k-p-4.1.0.CSCtr26695.tar installed. Also note that Cisco IOS XR Software can include multiple SMUs and the output may differ from the preceding example.

Products Confirmed Not Vulnerable

The following products are confirmed not vulnerable:

  • Cisco Carrier Routing System (CRS) running any version of Cisco IOS XR Software
  • Cisco XR 12000 Series Routers running any version of Cisco IOS XR Software
  • Cisco 12000 Series Routers running any version of Cisco IOS Software
  • Cisco IOS Software
  • Cisco IOS XE Software
  • Cisco NX-OS Software
  • Cisco ASR 1000 and 5000 Series routers running any version of software
  • Cisco ASR 9000 Series routers running any version of Cisco IOS XR Software other than 4.1.0
  • Cisco ASR 9000 Series routers running Cisco IOS XR Software version 4.1.0 and with the SMU asr9k-p-4.1.0.CSCtr26695.tar installed
    To determine which SMUs are active on the device, issue the show install active summary command. This will return a list of all SMUs installed:
    RP/0/0/CPU0:Router#show install active summary
    Fri Jul  8 19:02:15.887 CEST
      Active Packages:
        disk0:asr9k-p-4.1.0.CSCtr26695-1.0.0
        disk0:asr9k-p-4.1.0.CSCto96804-1.0.0
        disk0:asr9k-p-4.1.0.CSCto95435-1.0.0
        disk0:asr9k-doc-p-4.1.0
        disk0:asr9k-mini-p-4.1.0
        disk0:asr9k-k9sec-p-4.1.0
        disk0:asr9k-video-p-4.1.0
    Note: The preceding output shows a device with the SMU asr9k-p-4.1.0.CSCtr26695.tar installed (in bold). Also note that Cisco IOS XR Software can include multiple SMUs and the output may differ from the preceding example.

Details

Cisco ASR 9000 Series routers are designed to provide carrier-class reliability using the Cisco IOS XR Software modular operating system, offering service and application-level intelligence focused on optimized video delivery and mobile aggregation in Carrier Ethernet Services networks.

Cisco IOS XR Software is a distributed operating system designed for continuous system operation combined with service flexibility and high performance.

Cisco ASR 9000 Series devices running Cisco IOS XR Software version 4.1.0 contain a vulnerability that may cause a network processor in a line card to lock up while processing an IPv4 packet. As a consequence of the network processor lockup, the line card that is processing the offending packet will automatically reload.

This vulnerability can be triggered only by IPv4 packets. If only IP version 6 (IPv6) is in use, the device is not vulnerable.

Both transit IPv4 packets and IPv4 packets directed to the device itself may trigger this vulnerability.

One or both the following messages may appear in the system log:

  • PLATFORM-DIAGS-3-PUNT_FABRIC_DATA_PATH_FAILED
  • PLATFORM-DIAGS-0-LC_NP_LOOPBACK_FAILED

This vulnerability is documented as CSCtr26695 (registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2011-2549

Vulnerability Scoring Details

Cisco has provided scores for the vulnerabilities in this advisory based on the Common Vulnerability Scoring System (CVSS). The CVSS scoring in this Security Advisory is done in accordance with CVSS version 2.0.

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

Cisco has provided a base and temporal score. Customers can then compute environmental scores to assist in determining the impact of the vulnerability in individual networks.

Cisco has provided an FAQ to answer additional questions regarding CVSS at
http://www.cisco.com/web/about/security/intelligence/cvss-qandas.html .

Cisco has also provided a CVSS calculator to help compute the environmental impact for individual networks at
http://intellishield.cisco.com/security/alertmanager/cvss .

CSCtr26695 ASR9k:Line Card Issue with NP lockup

Calculate the environmental score of CSCtr26695

CVSS Base Score - 7.8

Access Vector

Access Complexity

Authentication

Confidentiality Impact

Integrity Impact

Availability Impact

Network

Low

None

None

None

Complete

CVSS Temporal Score - 6.8

Exploitability

Remediation Level

Report Confidence

High

Official-Fix

Confirmed

Impact

Successful exploitation of the vulnerability described in this advisory may cause the affected line card to reload. Repeated exploitation could result in a sustained denial of service (DoS) condition.

Software Versions and Fixes

When considering software upgrades, also consult http://www.cisco.com/go/psirt and any subsequent advisories to determine exposure and a complete upgrade solution.

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 Technical Assistance Center (TAC) or your contracted maintenance provider for assistance.

Each row of the Cisco IOS XR Software table (below) names a Cisco IOS XR Software release train. If a given release train is vulnerable, then the earliest possible releases that contain the fix, if available at the time of Advisory, are listed in the "First Fixed Release" column of the table.

Major Release

Availability of Repaired Releases

 

SMU ID

SMU Name

First Fixed Release

3.2.X through 4.0.X

Not affected

4.1.0

AA05118

asr9k-p-4.1.0.CSCtr26695.tar

4.1.1

Note: At the time of this advisory, Release 4.1.1 is expected to be available on July 29, 2011.

Workarounds

There are no workarounds for this vulnerability.

Obtaining Fixed Software

Cisco has released free software updates that address these vulnerabilities. Prior to deploying software, customers should consult their maintenance provider or check the software for feature set compatibility and known issues specific to their environment.

Customers may only install and expect support for the feature sets they have purchased. By installing, downloading, accessing or otherwise using such software upgrades, customers agree to be bound by the terms of Cisco's software license terms found at http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.html , or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public/sw-center/sw-usingswc.shtml .

Do not contact psirt@cisco.com or security-alert@cisco.com for software upgrades

Customers with Service Contracts

Customers with contracts should obtain upgraded software through their regular update channels. For most customers, this means that upgrades should be obtained through the Software Center on Cisco's worldwide website at http://www.cisco.com.

Customers using Third Party Support Organizations

Customers whose Cisco products 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 support organization for guidance and assistance with the appropriate course of action in regards to this advisory.

The effectiveness of any workaround or fix is dependent on specific customer situations, such as product mix, network topology, traffic behavior, and organizational mission. Due to the variety of affected products and releases, customers should consult with their service provider or support organization to ensure any applied workaround or fix is the most appropriate for use in the intended network before it is deployed.

Customers without Service Contracts

Customers who purchase direct from Cisco but do not hold a Cisco service contract, and customers who purchase through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should acquire 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

Customers should have their product serial number available and be prepared to give the URL of this notice as evidence of entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC.

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

Exploitation and Public Announcements

The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory.

This vulnerability was found during the resolution of multiple customer service requests.

We would like to thank the Internet Measurement Group from the University of Washington for their help and support on troubleshooting this issue.

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's worldwide website at:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20110720-asr9k

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
  • first-teams@first.org
  • bugtraq@securityfocus.com
  • vulnwatch@vulnwatch.org
  • cisco@spot.colorado.edu
  • cisco-nsp@puck.nether.net
  • full-disclosure@lists.grok.org.uk
  • comp.dcom.sys.cisco@newsgate.cisco.com

Future updates of this advisory, if any, will be placed on Cisco's worldwide website, but may or may not be actively announced on mailing lists or newsgroups. Users concerned about this problem are encouraged to check the above URL for any updates.


Revision History

Revision 1.0

2011-July-20

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 website at http://www.cisco.com/web/about/security/psirt/security_vulnerability_policy.html. This includes instructions for press inquiries regarding Cisco security notices. All Cisco security advisories are available at http://www.cisco.com/go/psirt.