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Cisco IOS XR Software Route Processor Denial of Service Vulnerability

Advisory ID: cisco-sa-20120530-iosxr

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120530-iosxr

Revision 2.1

Last Updated  2012 August 23 20:37  UTC (GMT)

For Public Release 2012 May 30 16:00  UTC (GMT)


Summary

Cisco IOS XR Software contains a vulnerability when handling crafted packets that may result in a denial of service condition. The vulnerability only exists on Cisco 9000 Series Aggregation Services Routers (ASR) Route Switch Processor (RSP-4G and RSP-8G), Route Switch Processor 440 (RSP440), and Cisco Carrier Routing System (CRS) Performance Route Processor (PRP). The vulnerability is a result of improper handling of crafted packets and could cause the route processor, which processes the packets, to be unable to transmit packets to the fabric.

Cisco has released free software updates that address this vulnerability. This advisory is available at the following link:
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120530-iosxr

Affected Products

This vulnerability affects IOS XR Software version 4.2.0 running on the Cisco ASR 9000 Series RSP440 and IOS XR Software versions prior to 4.2.0 running on the Cisco ASR 9000 Series RSP-4G or RSP-8G. It also affects IOS XR Software versions 4.0.3, 4.0.4, 4.1.0, 4.1.1, 4.1.2, and 4.2.0 running on the CRS Performance Route Processor.

Vulnerable Products

To determine the Cisco IOS XR 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 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 9000 series device that is running Cisco IOS XR Software Release 4.2.0:
RP/0/RSP1/CPU0:ASR9006-D#show version | inc Cisco IOS XR Software
Fri Apr 27 22:40:32.486 UTC
Cisco IOS XR Software, Version 4.2.0[Default]
The following example identifies a Cisco CRS series device that is running Cisco IOS XR Software Release 4.0.4:
RP/0/RP0/CPU0:CRS-G#show version | inc Cisco IOS XR Software
Fri Apr 27 22:28:14.304 UTC
Cisco IOS XR Software, Version 4.0.4[Default]
Additional information about Cisco IOS XR Software release naming conventions is available in "White Paper: Cisco IOS Reference Guide" at the following link: http://www.cisco.com/web/about/security/intelligence/ios-ref.html#9

Additional information about Cisco IOS XR Software time-based release model is available in "White Paper: Guidelines for Cisco IOS XR Software" at the following link: http://www.cisco.com/en/US/prod/collateral/iosswrel/ps8803/ps5845/product_bulletin_c25-478699.html

In order to determine whether a Cisco ASR 9000 series device with affected software is using an RSP440, the following command can be run:
RP/0/RSP0/CPU0:ASR9006-D#show inventory all | include Route Switch Processor
Thu May  3 18:50:46.129 UTC
NAME: "module 0/RSP0/CPU0", DESCR: "ASR9K Route Switch Processor with 440G/slot Fabric and 6GB"
NAME: "module 0/RSP1/CPU0", DESCR: "ASR9K Route Switch Processor with 440G/slot Fabric and 6GB"
Only devices that are equipped with Performance Route Processors are affected. In order to determine whether a Cisco CRS series device with affected software is using a Performance Route Processor, the following command can be run:
RP/0/RP0/CPU0:CRS-G#show inventory all | include Performance Route Processor
Wed May  2 14:49:06.994 EDT
NAME: "0/RP0/*", DESCR: "Cisco CRS Series 8 Slots 12 GB Performance Route Processor"
NAME: "0/RP1/*", DESCR: "Cisco CRS Series 8 Slots 12 GB Performance Route Processor"

Products Confirmed Not Vulnerable

Only Cisco ASR 9000 Series RSP440, RSP-4G, and RSP-8G devices and Cisco Carrier Routing System Performance Route Processor devices are affected.

No other Cisco products are currently known to be affected by this vulnerability, including other Route Processors such as the Cisco CRS-1 Distributed Route Processor (DRP), RP-A or RP-B.

Details

Cisco IOS XR Software is affected by this vulnerability, which is present on two different platforms with specific configurations.

Vulnerable software versions must be combined with one of the following Route Processors in order to be affected:

Platform
Route Processor Part ID
 ASR 9000
 A9K-RSP440-SE
 ASR 9000
 A9K-RSP440-TR
 ASR 9000  A9K-RSP-4G
 ASR 9000  A9K-RSP-8G
 CRS  CRS-8-PRP-6G
 CRS  CRS-8-PRP-12G
 CRS  CRS-16-PRP-6G
 CRS  CRS-16-PRP-12G


This vulnerability has been documented in Cisco Bug IDs CSCty94537 and CSCua63591 (ASR 9000) and CSCtz62593 (CRS) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2012-2488.

Cisco IOS XR Software Route Processor Denial of Service Vulnerability

Cisco IOS XR Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.

The vulnerability is due to improper processing of crafted packets by Cisco 9000 Series Aggregation Services Routers (ASR) Route Switch Processor (RSP-4G or RSP-8G), Route Switch Processor 440 (RSP440), or Carrier Routing System (CRS) Performance Route Processor. An attacker could exploit this vulnerability by sending a crafted packet to a vulnerable system; this vulnerability cannot be triggered by IP traffic transiting a vulnerable device. An exploit could allow the attacker to cause the packets originating on the Route Processor CPU to stop transmitting to the fabric, resulting in a DoS condition.

Vulnerability Scoring Details

Cisco has provided the score for the vulnerability 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 the 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 compute the environmental impact for individual networks at:

 

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

CSCty94537, CSCua63591, CSCtz62593 - Cisco IOS XR Software Route Processor Denial of Service Vulnerability

Calculate the environmental score of CSCty94537CSCua63591, and CSCtz62593

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 - 6.4

Exploitability

Remediation Level

Report Confidence

Functional

Official-Fix

Confirmed

Impact

Successful exploitation of the vulnerability could cause the route processor on an affected device to stop transmitting packets from the route processor CPU to the fabric. As a result, the affected RSP440, RSP-4G, RSP-8G, or Performance Route Processor will experience a DoS, failing to transmit all of its route processor-based protocols (for example, Intermediate System - Intermediate System, Border Gateway Protocol, ICMP).

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.

For IOS XR running on Cisco ASR 9000 Series RSP440, the vulnerability is present in software version 4.2.0 and is fixed with SMU name 4.2.0_asr9k-px_REC_SMUS_2012-05-15.tar.

For IOS XR running on Cisco ASR 9000 Series RSP-4G or RSP-8G, the vulnerability is present in versions prior to 4.2.0. The following SMUs for ASR 9000 Series RSP-4G or RSP-8G devices correct this vulnerability:

IOS XR Version
SMU ID
SMU Name
 4.0.1  AA06294 
 asr9k-p-4.0.1.CSCua63591
 4.0.3  AA06313  asr9k-p-4.0.3.CSCua63591
 4.1.0  AA06306  asr9k-p-4.1.0.CSCua63591
 4.1.1  AA06308  asr9k-p-4.1.1.CSCua63591
 4.1.2  AA06305  asr9k-p-4.1.2.CSCua63591

For IOS XR running on CRS Performance Route Processor, the vulnerability is present in versions 4.0.3, 4.0.4, 4.1.0, 4.1.1, 4.1.2, and 4.2.0. The following SMUs for CRS series devices correct this vulnerability:

IOS XR Version
SMU ID
SMU Name
4.0.3
AA06162  hfr-px-4.0.3.CSCtz62593
4.0.4 AA06161  hfr-px-4.0.4.CSCtz62593
4.1.0 AA06163  hfr-px-4.1.0.CSCtz62593
4.1.1 AA06164  hfr-px-4.1.1.CSCtz62593
4.1.2 AA06165  hfr-px-4.1.2.CSCtz62593
4.2.0 AA06166  hfr-px-4.2.0.CSCtz62593

This vulnerability will be fixed in IOS XR version 4.2.1 for both Cisco ASR 9000 series devices and CRS series devices.

Workarounds

There are no workarounds for the vulnerability described in this document.

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 provider or check the software for feature set compatibility and known issues that are 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.

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 while diagnosing issues encountered in customer networks.

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 Intelligence Operations at the following link:

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20120530-iosxr

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 2.1 2012-August-23 Doc updated to correct first published date
Revision 2.0 2012-August-15 Updated affected platforms to include RSP-4G and RSP-8G on ASR 9000 Series, prior to IOS XR 4.2.0
Revision 1.1 2012-May-31 Updated Software Versions and Fixes to clarify SMU names and to provide links to relevant Software Downloads pages
Revision 1.0 2012-May-30 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/en/US/products/products_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.