Products & Services
Support

Product Categories


Popular Downloads


Manage Software

How to Buy

For Home

Linksys Products Store
Linksys is now part of Belkin
Products for everyone

All Ordering Options

Training & Events Partners
Guest

Cisco Security Advisory

Cisco IOS MPLS Forwarding Infrastructure Denial of Service Vulnerability

Advisory ID: cisco-sa-20080924-mfi

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-mfi

Revision 1.1

For Public Release 2008 September 24 16:00  UTC (GMT)

Related Resources:

View related Alert

Summary

Cisco IOS Software Multi Protocol Label Switching (MPLS) Forwarding Infrastructure (MFI) is vulnerable to a Denial of Service (DoS) attack from specially crafted packets. Only the MFI is affected by this vulnerability. Older Label Forwarding Information Base (LFIB) implementation, which is replaced by MFI, is not affected.

Cisco has released free software updates that address this vulnerability.

This advisory is posted at http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20080924-mfi.

Note: The September 24, 2008 IOS Advisory bundled publication includes twelve Security Advisories. Eleven of the advisories address vulnerabilities in Cisco's IOS software, and one advisory addresses vulnerabilities in Cisco Unified Communications Manager. Each Advisory lists the releases that correct the vulnerability described in the Advisory.

Individual publication links are listed below:

Affected Products

Devices that run Cisco IOS software (including those that support Cisco IOS Software Modularity) and support MFI are affected if they are configured for MPLS.

Vulnerable Products

A device that runs Cisco IOS software and supports MFI will have mfi_ios in the output of the show subsys command. The following example shows output from a device that supports MFI:

Router#show subsys name mfi_ios
             Class         Version 
mfi_ios      Protocol    1.000.001
Router#

The following example shows output from a device that is configured for MPLS:

Router#show mpls interface
Interface      IP           Tunnel  BGP Static Operational 
Ethernet0/0    Yes (ldp)    No      No  No     Yes
Router#

To determine the software running on a Cisco product, log in to the device and issue the "show version" command to display the system banner. Cisco IOS software will identify itself as "Internetwork Operating System Software" or simply "IOS". On the next line of output, the image name will be displayed between parentheses, followed by "Version" and the IOS release name. Other Cisco devices will not have the "show version" command or will give different output.

The following example identifies a Cisco product that is running Cisco IOS release 12.4(11)T2:

Router#show version 
Cisco IOS Software,7200 Software (C7200-ADVSECURITYK9-M), Version 12.4(11)T2, RELEASE SOFTWARE (fc4) 
Technical Support: http://www.cisco.com/techsupport 
Copyright (c) 1986-2007 by Cisco Systems, Inc. 
Compiled Tue 01-May-07 04:19 by prod_rel_team
 
 <output truncated>

Additional information on the Cisco IOS release naming conventions can be found on the document entitled "White Paper: Cisco IOS Reference Guide", which is available at http://www.cisco.com/warp/public/620/1.html

Products Confirmed Not Vulnerable

Devices running Cisco IOS software versions that do not include MFI are not vulnerable.

Devices that are not configured for MPLS are not vulnerable.

Devices that are running Cisco IOS XR software are not vulnerable.

No other Cisco products are currently known to be affected by these vulnerabilities.

Details

In newer versions of Cisco IOS software, a new packet forwarding infrastructure was introduced to improve scalability and performance. This forwarding infrastructure, called MFI, is transparent to the user. MFI manages MPLS data structures used for forwarding and replaces the older implementation, Label Forwarding Information Base (LFIB). Cisco IOS MFI implementation is vulnerable to a DoS attack from specially crafted packets that are handled in the software path, including transit packets that are handled in the software path. Such packets can be sent from the local segment to the interfaces that are configured for MPLS or via tunnel interfaces that are configured for MPLS. To target a remote system in an MPLS network, an attacker needs to have access to the MPLS network through an MPLS-enabled interface. MPLS packets are dropped on interfaces that are not configured for MPLS.

Devices that support MFI will have mfi_ios in the output of the show subsys command. Interfaces that are enabled for MPLS can be seen by the show mpls interface command.

More information on MFI can be found at the following link:

http://www.cisco.com/en/US/docs/ios/mpls/configuration/guide/mp_lsc_removed.html

This vulnerability is documented in the Cisco Bug ID CSCsk93241 ( registered customers only) and has been assigned Common Vulnerabilities and Exposures (CVE) ID CVE-2008-3804.

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 .

CSCsk93241 - Chunk memory corruption on LFDp Input Proc

Calculate the environmental score of CSCsk93241

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 this vulnerability may result in the reload of the device, leading to a 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 software table (below) names a Cisco IOS release train. If a given release train is vulnerable, then the earliest possible releases that contain the fix (along with the anticipated date of availability for each, if applicable) are listed in the "First Fixed Release" column of the table. The "Recommended Release" column indicates the releases which have fixes for all the published vulnerabilities at the time of this Advisory. A device running a release in the given train that is earlier than the release in a specific column (less than the First Fixed Release) is known to be vulnerable. Cisco recommends upgrading to a release equal to or later than the release in the "Recommended Releases" column of the table.

Major Release

Availability of Repaired Releases

Affected 12.0-Based Releases

First Fixed Release

Recommended Release

There are no affected 12.0 based releases

Affected 12.1-Based Releases

First Fixed Release

Recommended Release

There are no affected 12.1 based releases

Affected 12.2-Based Releases

First Fixed Release

Recommended Release

12.2

Not Vulnerable

 

12.2B

Not Vulnerable

 

12.2BC

Not Vulnerable

 

12.2BW

Not Vulnerable

 

12.2BX

Not Vulnerable

 

12.2BY

Not Vulnerable

 

12.2BZ

Not Vulnerable

 

12.2CX

Not Vulnerable

 

12.2CY

Not Vulnerable

 

12.2CZ

Not Vulnerable

 

12.2DA

Not Vulnerable

 

12.2DD

Not Vulnerable

 

12.2DX

Not Vulnerable

 

12.2EW

Not Vulnerable

 

12.2EWA

Not Vulnerable

 

12.2EX

Not Vulnerable

 

12.2EY

12.2(44)EY; Available on 16-DEC-08

 

12.2EZ

Not Vulnerable

 

12.2FX

Not Vulnerable

 

12.2FY

Not Vulnerable

 

12.2FZ

Not Vulnerable

 

12.2IRB

Not Vulnerable

 

12.2IXA

Not Vulnerable

 

12.2IXB

Not Vulnerable

 

12.2IXC

Not Vulnerable

 

12.2IXD

Not Vulnerable

 

12.2IXE

Not Vulnerable

 

12.2IXF

Not Vulnerable

 

12.2IXG

Not Vulnerable

 

12.2JA

Not Vulnerable

 

12.2JK

Not Vulnerable

 

12.2MB

Not Vulnerable

 

12.2MC

Not Vulnerable

 

12.2S

Releases prior to 12.2(22)S are not vulnerable.

Release 12.2(22)S and later and prior to 12.2(30)S are vulnerable,

release 12.2(30)S and later are not vulnerable

12.2(33)SB2; Available on 26-SEP-08

12.2SB

12.2(31)SB12

12.2(33)SB

12.2(33)SB2; Available on 26-SEP-08

12.2SBC

Vulnerable; first fixed in 12.2SB

12.2(33)SB2; Available on 26-SEP-08

12.2SCA

12.2(33)SCA1

12.2(33)SCA1

12.2SE

12.2(44)SE3; Available on 30-SEP-08

12.2(46)SE

12.2(46)SE

12.2SEA

Not Vulnerable

 

12.2SEB

Not Vulnerable

 

12.2SEC

Not Vulnerable

 

12.2SED

Vulnerable; first fixed in 12.2SE

12.2(46)SE

12.2SEE

Vulnerable; first fixed in 12.2SE

12.2(46)SE

12.2SEF

Not Vulnerable

 

12.2SEG

Note: Releases prior to 12.2(25)SEG4 are vulnerable, release 12.2(25)SEG4 and later are not vulnerable;

12.2(25)SEG6

12.2SG

12.2(50)SG; Available on 24-NOV-08

12.2(46)SG1

12.2SGA

Not Vulnerable

 

12.2SL

Not Vulnerable

 

12.2SM

Not Vulnerable

 

12.2SO

Not Vulnerable

 

12.2SRA

Vulnerable; first fixed in 12.2SRB

12.2(33)SRB4

12.2(33)SRC2

12.2SRB

12.2(33)SRB4

12.2(33)SRB4

12.2SRC

12.2(33)SRC1

12.2(33)SRC2

12.2SU

Not Vulnerable

 

12.2SV

Vulnerable; contact TAC

 

12.2SVA

Vulnerable; contact TAC

 

12.2SVC

Vulnerable; contact TAC

 

12.2SVD

Vulnerable; contact TAC

 

12.2SW

Note: Releases prior to 12.2(25)SW4 are vulnerable, release 12.2(25)SW4 and later are not vulnerable;

12.2(25)SW12

12.2SX

Not Vulnerable

 

12.2SXA

Not Vulnerable

 

12.2SXB

Not Vulnerable

 

12.2SXD

Not Vulnerable

 

12.2SXE

Not Vulnerable

 

12.2SXF

Not Vulnerable

 

12.2SXH

12.2(33)SXH3

12.2(33)SXH3

12.2SY

Not Vulnerable

 

12.2SZ

Not Vulnerable

 

12.2T

Not Vulnerable

 

12.2TPC

Not Vulnerable

 

12.2XA

Not Vulnerable

 

12.2XB

Not Vulnerable

 

12.2XC

Not Vulnerable

 

12.2XD

Not Vulnerable

 

12.2XE

Not Vulnerable

 

12.2XF

Not Vulnerable

 

12.2XG

Not Vulnerable

 

12.2XH

Not Vulnerable

 

12.2XI

Not Vulnerable

 

12.2XJ

Not Vulnerable

 

12.2XK

Not Vulnerable

 

12.2XL

Not Vulnerable

 

12.2XM

Not Vulnerable

 

12.2XN

Vulnerable; first fixed in 12.2SB

12.2(33)SB2; Available on 26-SEP-08

12.2(33)SRC2

12.2(33)XNA2

12.2XNA

Not Vulnerable

 

12.2XNB

Not Vulnerable

 

12.2XO

Not Vulnerable

 

12.2XQ

Not Vulnerable

 

12.2XR

Not Vulnerable

 

12.2XS

Not Vulnerable

 

12.2XT

Not Vulnerable

 

12.2XU

Not Vulnerable

 

12.2XV

Not Vulnerable

 

12.2XW

Not Vulnerable

 

12.2YA

Not Vulnerable

 

12.2YB

Not Vulnerable

 

12.2YC

Not Vulnerable

 

12.2YD

Not Vulnerable

 

12.2YE

Not Vulnerable

 

12.2YF

Not Vulnerable

 

12.2YG

Not Vulnerable

 

12.2YH

Not Vulnerable

 

12.2YJ

Not Vulnerable

 

12.2YK

Not Vulnerable

 

12.2YL

Not Vulnerable

 

12.2YM

Not Vulnerable

 

12.2YN

Not Vulnerable

 

12.2YO

Not Vulnerable

 

12.2YP

Not Vulnerable

 

12.2YQ

Not Vulnerable

 

12.2YR

Not Vulnerable

 

12.2YS

Not Vulnerable

 

12.2YT

Not Vulnerable

 

12.2YU

Not Vulnerable

 

12.2YV

Not Vulnerable

 

12.2YW

Not Vulnerable

 

12.2YX

Not Vulnerable

 

12.2YY

Not Vulnerable

 

12.2YZ

Not Vulnerable

 

12.2ZA

Not Vulnerable

 

12.2ZB

Not Vulnerable

 

12.2ZC

Not Vulnerable

 

12.2ZD

Not Vulnerable

 

12.2ZE

Not Vulnerable

 

12.2ZF

Not Vulnerable

 

12.2ZG

Not Vulnerable

 

12.2ZH

Not Vulnerable

 

12.2ZJ

Not Vulnerable

 

12.2ZL

Not Vulnerable

 

12.2ZP

Not Vulnerable

 

12.2ZU

Not Vulnerable

 

12.2ZX

Vulnerable; first fixed in 12.2SB

12.2(33)SB2; Available on 26-SEP-08

12.2ZY

Not Vulnerable

 

12.2ZYA

Not Vulnerable

 

Affected 12.3-Based Releases

First Fixed Release

Recommended Release

There are no affected 12.3 based releases

Affected 12.4-Based Releases

First Fixed Release

Recommended Release

12.4

Not Vulnerable

 

12.4JA

Not Vulnerable

 

12.4JK

Not Vulnerable

 

12.4JL

Not Vulnerable

 

12.4JMA

Not Vulnerable

 

12.4JMB

Not Vulnerable

 

12.4JMC

Not Vulnerable

 

12.4JX

Not Vulnerable

 

12.4MD

Not Vulnerable

 

12.4MR

Not Vulnerable

 

12.4SW

Not Vulnerable

 

12.4T

Not Vulnerable

 

12.4XA

Not Vulnerable

 

12.4XB

Not Vulnerable

 

12.4XC

Not Vulnerable

 

12.4XD

Not Vulnerable

 

12.4XE

Not Vulnerable

 

12.4XF

Not Vulnerable

 

12.4XG

Not Vulnerable

 

12.4XJ

Not Vulnerable

 

12.4XK

Not Vulnerable

 

12.4XL

Not Vulnerable

 

12.4XM

Not Vulnerable

 

12.4XN

Not Vulnerable

 

12.4XP

Not Vulnerable

 

12.4XQ

12.4(15)XQ1

12.4(15)XQ1

12.4XR

Vulnerable; migrate to any release in 12.4T

12.4(15)T7

12.4XT

Not Vulnerable

 

12.4XV

Not Vulnerable

 

12.4XW

Not Vulnerable

 

12.4XY

12.4(15)XY4

12.4(15)XY4

12.4XZ

12.4(15)XZ1

12.4(15)XZ2

12.4YA

Not Vulnerable

 


Workarounds

MPLS is normally enabled on physical and logical interfaces that are shared with other MPLS-enabled devices. It can be disabled on interfaces where MPLS is not necessary and from which a potential attack can be launched. This action may help to limit the exposure of this vulnerability.

If it is not possible to disable MPLS on interfaces from which an attack can be launched, there are no workarounds to mitigate 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/warp/public/687/Directory/DirTAC.shtml 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 internally.

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-20080924-mfi

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-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
  • 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 1.1

2009-April-16

Removed references to the combined software table, as it is now outdated.

Revision 1.0

2008-Sep-24

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.


Download this document (PDF)
View Printable Version