__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Cisco Multiple Crafted IPv6 Packets Cause Reload [Cisco Document ID: 63844] January 26, 2005 17:00 GMT Number P-111 ______________________________________________________________________________ PROBLEM: 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. PLATFORM: Only the Cisco devices running IOS and configured for IPv6 are affected. DAMAGE: Successful exploitation of this vulnerability results in a reload of the device. Repeated exploitation could result in a sustained DoS attack. SOLUTION: Upgrade to the appropriate version. ______________________________________________________________________________ VULNERABILITY The risk is LOW. This vulnerability required multiple crafted ASSESSMENT: packats to be sent to the device which may result in a reload upon successful exploitation. There is limited impact on production networks. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/p-111.shtml ORIGINAL BULLETIN: Cisco Document ID: 63844 http://www.cisco.com/en/US/products/products_security_ advisory09186a00803be76e.shtml ______________________________________________________________________________ [***** Start Cisco Document ID: 63844 *****] Cisco Security Advisory: Multiple Crafted IPv6 Packets Cause Reload Document ID: 63844 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 Release Availability of Repaired Releases Affected 12.0-Based Release Rebuild Interim Maintenance 12.0S 12.0(23)S and before are not vulnerable. 12.0(24)S6 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 Release Rebuild Interim Maintenance 12.2B 12.2(2)B - 12.2(4)B7 Migrate to 12.2(13)T14 or later 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 12.2S 12.2(14)S9 12.2(18)S5 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 12.2T 12.2(13)T14 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 Release Rebuild Interim Maintenance 12.3 12.3(3f) 12.3(5c) 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 12.3T 12.3(2)T6 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 1.0 2005-January-26 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/en/US/products/ products_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. [***** End Cisco Document ID: 63844 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Cisco Systems for the information contained in this bulletin. _______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 (7x24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@ciac.org Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ Anonymous FTP: ftp.ciac.org PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. 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