-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Cisco Security Advisory: Multiple Crafted IPv6 Packets Cause Reload Revision 1.0 For Public Release 2005 January 26 1600 UTC (GMT) - -------------------------------------------------------------------------- Contents Summary Affected Products Details Impact Software Versions and Fixes Obtaining Fixed Software Workarounds Exploitation and Public Announcements Status of This Notice: FINAL Distribution Revision History Cisco Security Procedures - -------------------------------------------------------------------------- Summary ======= Cisco Internetwork Operating System (IOS) Software is vulnerable to a Denial of Service (DoS) attack from crafted IPv6 packets when the device has been configured to process IPv6 traffic. This vulnerability requires multiple crafted packets to be sent to the device which may result in a reload upon successful exploitation. Cisco has made free software available to address this vulnerability. There are workarounds available to mitigate the effects. This issue is tracked by CERT/CC VU#472582 This advisory is available at http://www.cisco.com/warp/public/707/cisco-sa-20050126-ipv6.shtml. Affected Products ================= Vulnerable Products Only the Cisco devices running IOS and configured for IPv6 are affected. A router will display all IPv6 enabled interfaces with the show ipv6 interface command. An empty output or an error message will be displayed if IPv6 is disabled or unsupported on the system. In this case the system is not vulnerable. Sample output of show ipv6 interface command is shown below for a system configured for IPv6. 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 [TENTATIVE] 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. Products Confirmed Not Vulnerable * Products that are not running Cisco IOS 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 that can be exploited to cause the reload of a system. Crafted packets received on logical interfaces (that is, tunnels including 6to4 tunnels) as well as physical interfaces can trigger this vulnerability. Multiple crafted IPv6 packets need to be sent to exploit this vulnerability. Such crafted packets can be sent remotely. This issue is documented in Cisco bug ID CSCed40933 ( registered customers only) . Impact ====== Successful exploitation of this vulnerability results in a reload of the device. Repeated exploitation could result in a sustained DoS attack. Software Versions and Fixes =========================== +-----------------------------------------------------+ | Major | Availability of Repaired Releases | | Release | | |------------+----------------------------------------| | Affected | | | | | | 12.0-Based | Rebuild | Interim | Maintenance | | | Release | | | | | |------------+-------------+---------+-------------+--| | | 12.0(23)S | | | | | | and before | | | | | | are not | | | | | | vulnerable. | | | | | |-------------+---------+-------------+--| | | 12.0(24)S6 | | | | |12.0S |-------------+---------+-------------+--| | | 12.0(25)S3 | | | | | |-------------+---------+-------------+--| | | 12.0(26)S2 | | | | | |-------------+---------+-------------+--| | | 12.0(27)S1 | | | | | |-------------+---------+-------------+--| | | | | 12.0(28)S | | |------------+-------------+---------+-------------+--| | 12.0SX | 12.0(25)SX8 | | | | |------------+-------------------------------------+--| | 12.0SZ | 12.0(27)SZ | | |------------+-------------------------------------+--| | Affected | | | | | | 12.2-Based | Rebuild | Interim | Maintenance | | | Release | | | | | |------------+-------------------------------------+--| | | 12.2(2)B - 12.2(4)B7 Migrate to | | | | 12.2(13)T14 or later | | |12.2B |-------------------------------------+--| | | 12.2(4)B8 AND FWD Migrate to 12.3 | | | | (7)T or later | | |------------+-------------------------------------+--| | 12.2BC | Migrate to 12.3(9a)BC | | |------------+-------------------------------------+--| | 12.2BX | Migrate to 12.3(7)XI1 | | |------------+-------------------------------------+--| | 12.2BZ | Migrate to 12.3(7)XI1 | | |------------+-------------------------------------+--| | 12.2CX | No plan. | | |------------+-------------------------------------+--| | 12.2CZ | No plan. | | |------------+-------------------------------------+--| | 12.2EW | 12.2(18)EW1 | | |------------+-------------------------------------+--| | 12.2EWA | | | 12.2(20)EWA | | |------------+-------------+---------+-------------+--| | 12.2JK | 12.2(15)JK2 | | | | |------------+-------------------------------------+--| | 12.2MC | Migrate to 12.3(11)T | | |------------+-------------------------------------+--| | | 12.2(14)S9 | | | | | |-------------+---------+-------------+--| | | 12.2(18)S5 | | | | | |-------------+---------+-------------+--| | 12.2S | 12.2(20)S3 | | | | | |-------------+---------+-------------+--| | | 12.2(22)S1 | | | | | |-------------+---------+-------------+--| | | | | 12.2(25)S | | |------------+-------------------------------------+--| | 12.2SE | 12.2(25)SE | | |------------+-------------------------------------+--| | 12.2SU | 12.2(14)SU1 | | | | |------------+-------------------------------------+--| | 12.2SV | 12.2(23)SV | | |------------+-------------------------------------+--| | 12.2SW | 12.2(23)SW | | |------------+-------------------------------------+--| | 12.2SX | Migrate to 12.2(17d)SXB2 or later | | |------------+-------------------------------------+--| | 12.2SXA | Migrate to 12.2(17d)SXB1 or later | | |------------+-------------------------------------+--| | 12.2SXB | 12.2(17d) | | | | | | SXB1 | | | | |------------+-------------+---------+-------------+--| | 12.2SXD | | | 12.2(18)SXD | | |------------+-------------------------------------+--| | 12.2SY | Migrate to 12.2(17d)SXB2 or later | | |------------+-------------------------------------+--| | 12.2SZ | Migrate to 12.2(20)S4 | | |------------+-------------------------------------+--| | | 12.2(13)T14 | | | | |12.2T |-------------+---------+-------------+--| | | 12.2(15)T12 | | | | |------------+-------------------------------------+--| | 12.2YT | Migrate to 12.2(15)T13 or later | | |------------+-------------------------------------+--| | 12.2YU | Migrate to 12.3(4)T6 or later | | |------------+-------------------------------------+--| | 12.2YV | Migrate to 12.3(4)T6 or later | | |------------+-------------------------------------+--| | 12.2YZ | Migrate to 12.2(20)S4 or later | | |------------+-------------------------------------+--| | 12.2ZC | Migrate to 12.3T or later | | |------------+-------------------------------------+--| | 12.2ZD | Migrate to 12.3 or later | | |------------+-------------------------------------+--| | 12.2ZE | Migrate to 12.3 or later | | |------------+-------------------------------------+--| | 12.2ZF | Migrate to 12.3(4)T6 or later | | |------------+-------------------------------------+--| | 12.2ZG | Migrate to 12.3(4)T6 or later | | |------------+-------------------------------------+--| | 12.2ZH | Migrate to 12.3(4)T6 or later | | |------------+-------------------------------------+--| | 12.2ZI | Migrate to 12.2(18)S or later | | |------------+-------------------------------------+--| | 12.2ZJ | Migrate to 12.3 or later | | |------------+-------------------------------------+--| | 12.2ZL | Migrate to 12.3(7)T or later | | |------------+-------------------------------------+--| | 12.2ZN | Migrate to 12.3(2)T6 or later | | |------------+-------------------------------------+--| | 12.2ZO | Migrate to 12.2(15)T12 or later | | |------------+-------------------------------------+--| | 12.2ZP | Migrate to 12.3(8)XY or later | | |------------+-------------------------------------+--| | Affected | | | | | | 12.3-Based | Rebuild | Interim | Maintenance | | | Release | | | | | |------------+-------------+---------+-------------+--| | | 12.3(3f) | | | | | |-------------+---------+-------------+--| | | 12.3(5c) | | | | |12.3 |-------------+---------+-------------+--| | | 12.3(6a) | | | | | |-------------+---------+-------------+--| | | | | 12.3(9) | | |------------+-------------+---------+-------------+--| | 12.3BC | | | 12.3(9a)BC | | |------------+-------------+---------+-------------+--| | 12.3B | 12.3(5a)B2 | | | | |------------+-------------------------------------+--| | 12.3BW | Migrate to 12.3(5a)B2 or later | | |------------+-------------------------------------+--| | 12.3JA | | | 12.3(2)JA | | |------------+-------------+---------+-------------+--| | | 12.3(2)T6 | | | | | |-------------+---------+-------------+--| | 12.3T | 12.3(4)T6 | | | | | |-------------+---------+-------------+--| | | | | 12.3(7)T | | |------------+-------------------------------------+--| | 12.3XA | Migrate to 12.3(7)T or later | | |------------+-------------------------------------+--| | 12.3XB | Migrate to 12.3(8)T or later | | |------------+-------------------------------------+--| | 12.3XC | Migrate 12.3(2)XC3 or later | | |------------+-------------------------------------+--| | 12.3XD | 12.3(4)XD4 | | | | |------------+-------------------------------------+--| | 12.3XE | 12.3(2)XE1 | | |------------+-------------------------------------+--| | 12.3XF | Migrate to 12.3(11)T or later | | |------------+-------------------------------------+--| | 12.3XG | 12.3(4)XG2 | | | | |------------+-------------------------------------+--| | 12.3XH | Migrate to 12.3(11)T or later | | |------------+-------------------------------------+--| | 12.3XI | | | 12.3(7)XI | | |------------+-------------------------------------+--| | 12.3XJ | 12.3(7)XJ | | |------------+-------------------------------------+--| | 12.3XK | 12.3(4)XK1 | | | | |------------+-------------+---------+-------------+--| | 12.3XL | | | 12.3(7)XL | | |------------+-------------+---------+-------------+--| | 12.3XM | | | 12.3(7)XM | | |------------+-------------------------------------+--| | 12.3XN | Migrate to 12.3(14)T or later | | |------------+-------------------------------------+--| | 12.3XQ | 12.3(4)XQ | | |------------+-------------------------------------+--| | 12.3XR | | | 12.3(7)XR | | |------------+-------------------------------------+--| | 12.3XS | 12.3(7)XS | | |------------+-------------------------------------+--| | 12.3XT | 12.3(2)XT | | |------------+-------------------------------------+--| | 12.3XU | 12.3(8)XU | | |------------+-------------------------------------+--| | 12.3XX | | | 12.3(8)XX | | |------------+-------------+---------+-------------+--| | 12.3XW | | | 12.3(8)XW | | |------------+-------------+---------+-------------+--| | 12.3XY | | | 12.3(8)XY | | |------------+-------------+---------+-------------+--| | 12.3XZ | | | 12.3(2)XZ | | |------------+-------------+---------+-------------+--| | 12.3YA | | | 12.3(8)YA | | |------------+-------------+---------+-------------+--| | 12.3YD | | | 12.3(8)YD | | |------------+-------------+---------+-------------+--| | 12.3YE | | | 12.3(4)YE | | |------------+-------------+---------+-------------+--| | 12.3YF | | | 12.3(11)YF | | |------------+-------------+---------+-------------+--| | 12.3YG | | | 12.3(8)YG | | |------------+-------------+---------+-------------+--| | 12.3YH | | | 12.3(8)YH | | +-----------------------------------------------------+ When considering software upgrades, please also consult http://www.cisco.com/en /US/products/products_security_advisories_listing.html 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) for assistance. Obtaining Fixed Software ======================== 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 agreement with third-party support organizations such as Cisco Partners, authorized resellers, or service providers should contact that support organization for assistance with the upgrade, which should be free of charge. Customers without Service Contracts Customers who purchase direct from Cisco but who do not hold a Cisco service contract and customers who purchase through third-party vendors but are unsuccessful at obtaining fixed software through their point of sale should get their 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 Please have your product serial number available and give the URL of this notice as evidence of your entitlement to a free upgrade. Free upgrades for non-contract customers must be requested through the TAC. Please do not contact either "psirt@cisco.com" or "security-alert@cisco.com" for software upgrades. See http://www.cisco.com/warp/public/687/Directory/DirTAC.shtml for additional TAC contact information, including special localized telephone numbers and instructions and e-mail addresses for use in various languages. 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/public/sw-license-agreement.html, or as otherwise set forth at Cisco.com Downloads at http://www.cisco.com/public /sw-center/sw-usingswc.shtml. 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. Although it is often difficult to block traffic transiting your network, it is possible to identify traffic which should never be allowed to target your infrastructure devices and block that traffic at the border of your network. Infrastructure access control lists (ACLs) are considered a network security best practice and should be considered as a long-term addition to good network security as well as a workaround for this specific vulnerability. The white paper entitled "Protecting Your Core: Infrastructure Protection Access Control Lists", available at http://www.cisco.com/warp/public/707/iacl.html, presents guidelines and recommended deployment techniques for infrastructure protection ACLs. Exceptions would include any devices which have a legitimate reason to access your infrastructure (for example, BGP peers, DNS servers, and so on). All other traffic must be able to traverse your network without terminating on any of your devices. Exploitation and Public Announcements ===================================== The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerability described in this advisory. Status of This Notice: FINAL ============================ THIS ADVISORY IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF THE INFORMATION ON THE ADVISORY OR MATERIALS LINKED FROM THE ADVISORY IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS NOTICE AT ANY TIME. A stand-alone copy or paraphrase of the text of this security advisory 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 will be posted on Cisco's worldwide website at http:// www.cisco.com/warp/public/707/cisco-sa-20050126-ipv6.shtml. 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 (includes CERT/CC) * bugtraq@securityfocus.com * vulnwatch@vulnwatch.org * cisco@spot.colorado.edu * cisco-nsp@puck.nether.net * full-disclosure@lists.netsys.com * comp.dcom.sys.cisco@newsgate.cisco.com * Various internal Cisco mailing lists 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 | 2005-January-26 | Initial public | | 1.0 | | 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/en/US/products/products_security_vulnerability_policy.h... . This includes instructions for press inquiries regarding Cisco security notices. All Cisco security advisories are available at http://www.cisco.com/go /psirt. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (GNU/Linux) iD8DBQFB97ElezGozzK2tZARAnf7AKCaIOMqvct4DE93oqAztxQJCT2KcgCg127I LHNvmFV/3Dga2ijk5r5XuP8= =HD3z -----END PGP SIGNATURE-----