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Cisco Security Advisory

IPv6 Crafted Packet Vulnerability

Advisory ID: cisco-sa-20050729-ipv6

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20050729-ipv6

Revision 2.0

For Public Release 2005 July 29 08:00  UTC (GMT)

Related Resources:

View related Alert

Summary

Cisco Internetwork Operating System (IOS®) Software is vulnerable to a Denial of Service (DoS) and potentially an arbitrary code execution attack from a specifically crafted IPv6 packet. The packet must be sent from a local network segment. Only devices that have been explicitly configured to process IPv6 traffic are affected. Upon successful exploitation, the device may reload or be open to further exploitation.

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-20050729-ipv6.

Affected Products

Vulnerable Products

This issue affects all Cisco devices running any unfixed version of Cisco IOS or Cisco IOS XR code that supports, and is configured for, IPv6. A system which supports IPv6, if not specifically configured for IPv6, is not affected. You can use the show ipv6 interface command to determine whether IPv6 is enabled on a system.

Sample output of the show ipv6 interface command is shown below for two systems, one not configured for IPv6 and one configured for IPv6.

An empty output or an error message will be displayed if IPv6 is disabled or unsupported on the system.

Router#show ipv6 int fa 0/0

-here you see blank output

In the example below the system is vulnerable.

Router#show ipv6 interface
Serial1/0 is up, line protocol is up
  IPv6 is enabled, link-local address is FE80::A8BB:CCFF:FE00:D200
  Global unicast address(es):
    2001:1:33::3, subnet is 2001:1:33::/64 
  Joined group address(es):
    FF02::1
    FF02::1:FF00:3
    FF02::1:FF00:D200
  MTU is 1500 bytes
  ICMP error messages limited to one every 100 milliseconds
  ICMP redirects are enabled
  ND DAD is enabled, number of DAD attempts: 1
  ND reachable time is 30000 milliseconds
Router#

A router that has IPv6 enabled on a physical or logical interface is vulnerable to this issue even if ipv6 unicast-routing is globally disabled. The show ipv6 interface command can be used to determine whether IPv6 is enabled on any interface.

Note:  Cisco 6500 and 7600 series systems that run 12.2(17a)SX, 12.2(17b)SXA or 12.2(17d)SXB based images automatically enable IPv6 on interfaces where Multi Protocol Label Switching (MPLS) is enabled. MPLS is enabled on an interface by the mpls ip or tag-switching ip commands. You can use the show ipv6 interface command to determine whether IPv6 is enabled on any interface.

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 shows a product running IOS release 12.3(6) with an image name of C2600-JS-MZ:

Cisco Internetwork Operating System Software IOS (tm)

C2600 Software (C2600-JS-MZ), Version 12.3(6), RELEASE SOFTWARE (fc1)

Additional information about Cisco IOS release naming can be found at http://www.cisco.com/web/about/security/intelligence/ios-ref.html.

A system that is running a Cisco IOS XR version prior to 3.2 is also affected by this vulnerability if configured for IPv6. The show ipv6 interface command can be used to identify whether IPv6 is enabled on a system running Cisco IOS XR.

Products Confirmed Not Vulnerable

Products that are not running Cisco IOS or Cisco IOS XR are not affected.

Products running any version of Cisco IOS that do not have IPv6 configured interfaces are not vulnerable.

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

Details

IPv6 is the "Internet Protocol Version 6", designed by the Internet Engineering Task Force (IETF) to replace the current version Internet Protocol, IP Version 4 (IPv4).

A vulnerability exists in the processing of IPv6 packets. Crafted packets from the local segment received on logical interfaces (that is, tunnels including 6to4 tunnels) as well as physical interfaces can trigger this vulnerability. Crafted packets can not traverse a 6to4 tunnel and attack a box across the tunnel.

The crafted packet must be sent from a local network segment to trigger the attack. This vulnerability can not be exploited one or more hops from the IOS device.

This issue is documented in Cisco bug ID CSCef68324 ( registered customers only) for Cisco IOS, and CSCeh74956 ( registered customers only) for Cisco IOS XR.

Vulnerability Scoring Details

Cisco has not provided scores for the vulnerability in this advisory based on the Common Vulnerability Scoring System (CVSS).  At the time of original publication, CVSS scoring in Cisco security publications was not yet adopted

Impact

Successful exploitation of the vulnerability on Cisco IOS may result in a reload of the device or execution of arbitrary code. Repeated exploitation could result in a sustained DoS attack or execution of arbitrary code on Cisco IOS devices.

Successful exploitation of the vulnerability on Cisco IOS-XR may result in a restart of the IPv6 neighbor discovery process. A restart of this process will only affect IPv6 traffic passing through the system. All other processes and traffic will be unaffected. Repeated exploitation could result in a sustained DoS attack on IPv6 traffic.

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 describes a release train and the platforms or products for which it is intended. If a given release train is vulnerable, then the earliest possible releases that contain the fix (the First Fixed Release) and the anticipated date of availability for each are listed in the Rebuild and Maintenance columns. 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. The release should be upgraded at least to the indicated release or a later version (greater than or equal to the First Fixed Release label).

Major Release

Availability of Repaired Releases

Affected 12.0-Based Release

Rebuild

Maintenance

12.0S

12.0(26)S6

 
 

12.0(27)S5

 
 

12.0(28)S3

 
 

12.0(30)S2

12.0(31)S

12.0SL

Vulnerable; migrate to 12.0(31)S or later

12.0ST

Vulnerable; migrate to 12.0(31)S or later

12.0SY

Vulnerable; migrate to 12.0(31)S or later

Affected 12.1-Based Release

Rebuild

Maintenance

12.1XU

Vulnerable; migrate to 12.3(15) or later

12.1XV

Vulnerable; migrate to 12.3(15) or later

12.1YB

Vulnerable; migrate to 12.3(15) or later

12.1YC

Vulnerable; migrate to 12.3(15) or later

12.1YD

Vulnerable; migrate to 12.3(15) or later

12.1YE

Vulnerable; migrate to 12.3(15) or later

12.1YF

Vulnerable; migrate to 12.3(15) or later

12.1YH

Vulnerable; migrate to 12.3(15) or later

12.1YI

Vulnerable; migrate to 12.3(15) or later

Affected 12.2-Based Release

Rebuild

Maintenance

12.2B

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2BC

12.2(15)BC2h

12.2BW

Vulnerable; migrate to 12.3(15) or later

12.2BY

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2BX

Vulnerable; migrate to 12.3(7)XI4 or later

12.2BZ

Vulnerable; migrate to 12.3(7)XI4 or later

12.2CX

Vulnerable; migrate to 12.3(13a)BC or later

12.2CY

Vulnerable; migrate to 12.3(13a)BC or later

12.2DD

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2DX

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2EU

12.2(20)EU1

 

12.2EW

12.2(20)EW2

 

12.2EWA

12.2(20)EWA2

12.2(25)EWA1

 

12.2EZ

12.2(25)EZ1

 

12.2JA

Vulnerable; migrate to 12.3(4)JA or later

12.2JK

12.2(15)JK4

12.2MB

12.2(4)MB13b

 

12.2MC

12.2(15)MC2c

12.2(15)MC1c is vulnerable; migrate to 12.4(2)MR

12.2MX

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2S

12.2(14)S14

 

12.2(18)S9

 

12.2(20)S8

 

12.2(25)S4

 

12.2SEB

12.2(25)SEB3

12.2SEC

12.2(25)SEC1

12.2SO

Vulnerable; contact TAC

12.2SU

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2SV

12.2(18)SV3, 12.2(22)SV1, 12.2(23)SV1, 12.2(24)SV1, 12.2(25)SV2

12.2(26)SV

12.2SW

12.2(25)SW3a

12.2SX

Vulnerable; migrate to 12.2(17d)SXB8 or later

12.2SXA

Vulnerable; migrate to 12.2(17d)SXB8 or later

12.2SXB

12.2(17d)SXB8

 

12.2SXD

12.2(18)SXD4

 

12.2SXE

12.2(18)SXE1

 

12.2SY

Vulnerable; migrate to 12.2(17d)SXB8 or later

12.2SZ

Vulnerable; migrate to 12.2(20)S8 or later

12.2T

12.2(13)T16

 

12.2(15)T16

 

12.2XA

Vulnerable; migrate to 12.3(15) or later

12.2XB

Vulnerable; migrate to 12.3(15) or later

12.2XC

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2XD

Vulnerable; migrate to 12.3(15) or later

12.2XE

Vulnerable; migrate to 12.3(15) or later

12.2XF

Vulnerable; migrate to 12.3(13a)BC or later

12.2XG

Vulnerable; migrate to 12.3(15) or later

12.2XH

Vulnerable; migrate to 12.3(15) or later

12.2XI

Vulnerable; migrate to 12.3(15) or later

12.2XJ

Vulnerable; migrate to 12.3(15) or later

12.2XK

Vulnerable; migrate to 12.3(15) or later

12.2XL

Vulnerable; migrate to 12.3(15) or later

12.2XM

Vulnerable; migrate to 12.3(15) or later

12.2XN

Vulnerable; migrate to 12.3(15) or later

12.2XQ

Vulnerable; migrate to 12.3(15) or later

12.2XR

Vulnerable; migrate to 12.3(4)JA or later

12.2XT

Vulnerable; migrate to 12.3(15) or later

12.2XU

Vulnerable; migrate to 12.3(15) or later

12.2XW

Vulnerable; migrate to 12.3(15) or later

12.2XZ

Vulnerable; migrate to 12.3(15) or later

12.2YA

12.2(4)YA10

 

12.2YB

Vulnerable; migrate to 12.3(15) or later

12.2YC

Vulnerable; migrate to 12.3(15) or later

12.2YD

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2YE

Vulnerable; migrate to 12.2(25)S4 or later

12.2YF

Vulnerable; migrate to 12.3(15) or later

12.2YG

Vulnerable; migrate to 12.3(15) or later

12.2YH

Vulnerable; migrate to 12.3(15) or later

12.2YJ

Vulnerable; migrate to 12.3(15) or later

12.2YK

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2YL

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2YM

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2YN

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2YO

Vulnerable; migrate to 12.2(17d)SXB8 or later

12.2YP

Vulnerable; migrate to 12.3(15) or later

12.2YQ

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2YR

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2YT

Vulnerable; migrate to 12.2(15)T16 or later

12.2YU

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2YV

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2YW

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2YX

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2YY

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2YZ

Vulnerable; migrate to 12.2(20)S8 or later

12.2ZA

Vulnerable; migrate to 12.2(17d)SXB8 or later

12.2ZB

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2ZC

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2ZD

12.2(13)ZD3

 

12.2ZE

Vulnerable; migrate to 12.3(15) or later

12.2ZF

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2ZG

Vulnerable; contact TAC

12.2ZH

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2ZJ

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2ZL

Vulnerable; contact TAC

12.2ZN

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.2ZO

Vulnerable; migrate to 12.2(15)T16 or later

12.2ZP

Vulnerable; migrate to 12.3(8)XY6 or later

Affected 12.3-Based Release

Rebuild

Maintenance

12.3

12.3(3h)

 

12.3(5e)

 

12.3(6e)

 

12.3(9d)

 

12.3(10d)

 

12.3(12b)

 

12.3(13a)

12.3(15)

12.3B

12.3(5a)B5

 

12.3BC

12.3(9a)BC6

12.3(13a)BC

12.3BW

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.3JA

 

12.3(4)JA

12.3JK

 

12.3(2)JK

12.3T

12.3(7)T9

 

12.3(8)T8

 

12.3(11)T5

 

12.3(14)T2

 

12.3XA

12.3(2)XA4

12.3XB

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.3XC

12.3(2)XC3

 

12.3XD

Vulnerable; contact TAC

12.3XE

12.3(2)XE3

12.3XF

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.3XG

12.3(4)XG4

12.3XH

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.3XI

12.3(7)XI4

 

12.3XJ

Vulnerable; migrate to 12.3(11)YF3 or later

12.3XK

12.3(4)XK3

12.3XL

Vulnerable; contact TAC

12.3XM

Vulnerable; migrate to fixed 12.3(14)T2 or later

12.3XQ

12.3(4)XQ1

 

12.3XR

12.3(7)XR4

 

12.3XS

Vulnerable; migrate to 12.4(1) or later

12.3XT

Vulnerable; contact TAC

12.3XU

Vulnerable; migrate to 12.4(2)T or later

12.3XW

Vulnerable; migrate to 12.3(11)YF3 or later

12.3XX

Vulnerable; migrate to 12.4(1) or later

12.3XY

12.3(8)XY6

 

12.3YA

12.3(8)YA1

 

12.3YD

Vulnerable; migrate to 12.4(2)T

12.3YF

12.3(11)YF3

 

12.3YG

12.3(8)YG2

 

12.3YH

Vulnerable; migrate to 12.3(8)YI1 or later

12.3YI

12.3(8)YI1

 

12.3YJ

12.3(11)YJ

 

12.3YK

Vulnerable; contact TAC

12.3YQ

12.3(14)YQ1

 

12.3YS

 

12.3(11)YS

12.3YT

 

12.3(14)YT

12.3YU

 

12.3(14)YU

Affected 12.4-Based Release

Rebuild

Maintenance

12.4

 

12.4(1)

12.4MR

 

12.4(2)MR

12.4T

 

12.4(2)T

Product

First Fixed Release

Cisco IOS XR

IOS XR 3.2

Contact TAC to obtain SMU AA01233 for IOS XR 3.0.1.

Contact TAC to obtain SMU AA01234 for IOS XR 3.1.0.

For further information on the terms "Rebuild" and "Maintenance, " please consult the following URL: http://www.cisco.com/web/about/security/intelligence/ios-ref.html


Workarounds

The effectiveness of any workaround 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 is the most appropriate for use in the intended network before it is deployed.

In networks where IPv6 is not needed but enabled, disabling IPv6 processing on an IOS device will eliminate exposure to this vulnerability. On a router which is configured for IPv6, this must be done by issuing the command no ipv6 enable and no ipv6 address on each interface.

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

This vulnerability was disclosed on July 27, 2005 at the Black Hat security conference.

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-20050729-ipv6

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 1.8

2005-August-11

Status changed from Interim to Final.

Revision 1.7

2005-August-05

Software Versions and Fixes table updated for Cisco IOS XR.

Revision 1.6

2005-August-03

Added a note to the Affected Products section. Software Versions and Fixes table updated for 12.2EZ.

Revision 1.5

2005-August-02

Software Versions and Fixes table updated for 12.2JK, 12.2MC, 12.2ZD, 12.3XA, 12.3XE, 12.3XG, and 12.3XK; removed 12.2CZ.

Revision 1.4

2005-August-01

Software Versions and Fixes table updated for 12.2BC, 12.2EZ, 12.2SEB, and 12.2SW.

Revision 1.3

2005-July-31

Software Versions and Fixes table updated.

Revision 1.2

2005-July-30

IOS XR added to Affected Products. Wording changes made in the Workarounds section. Software Versions and Fixes table updated.

Revision 1.1

2005-July-29

Software Versions and Fixes table updated. First paragraph in the Vulnerable Products section updated.

Revision 1.0

2005-July-29

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.


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