Cisco Security Advisory-
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 software updates that address this vulnerability.
This advisory is posted at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20050729-ipv6.
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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.
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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.
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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.
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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
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This vulnerability was disclosed on July 27, 2005 at the Black Hat security conference.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show LessRevision 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.
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