__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Cisco RADIUS Authentication Bypass [Cisco Security Advisory Document ID: 65328] June 29, 2005 17:00 GMT Number P-237 [REVISED 01 Jul 2005] ______________________________________________________________________________ PROBLEM: Remote Authentication Dial In User Service (RADIUS) authentication on a device that is running certain versions of Cisco Internetworking Operating System (IOS) and configured with a fallback method to none can be bypassed. PLATFORM: Systems that are running the following release trains of Cisco IOS are affected if configured with RADIUS authentication and a none fallback method. * 12.2T based trains * 12.3 based trains * 12.3T based trains * 12.4 based trains DAMAGE: Successful exploitation of the vulnerability may result in bypassing the RADIUS authentication. SOLUTION: Upgrade to the appropriate version. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. Successful exploitation of the ASSESSMENT: vulnerability may result in bypassing the RADIUS authentication. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/p-237.shtml ORIGINAL BULLETIN: Cisco Security Advisory Document ID: 65328 http://www.cisco.com/en/US/products/products_security_ advisory09186a00804ae616.shtml ______________________________________________________________________________ REVISION HISTORY: 07/01/05 - revised to note change to Cisco Document ID: 65328, revision 1.1. Cisco added some new software to the Software Version and Fixes Table section. [***** Start Cisco Security Advisory Document ID: 65328 *****] Cisco Security Advisory:RADIUS Authentication Bypass Document ID: 65328 Revision 1.1 Last Updated 2005 July 1 1800 UTC For Public Release 2005 June 29 1600 UTC -------------------------------------------------------------------------------- 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 Remote Authentication Dial In User Service (RADIUS) authentication on a device that is running certain versions of Cisco Internetworking Operating System (IOS) and configured with a fallback method to none can be bypassed. Systems that are configured for other authentication methods or that are not configured with a fallback method to none are not affected. Only the systems that are running certain versions of Cisco IOSŪ are affected. Not all configurations using RADIUS and none are vulnerable to this issue. Some configurations using RADIUS, none and an additional method are not affected. Cisco has made free software available to address this vulnerability. There are workarounds available to mitigate the effects of the vulnerability. The vulnerabilities are documented as the following Cisco Bug IDs: CSCee45312 -- Radius authentication bypass when configured with a none fallback method This advisory will be posted at http://www.cisco.com/warp/public/707/cisco-sa-20050629-aaa.shtml. Affected Products Vulnerable Products Systems that are running the following release trains of Cisco IOS are affected if configured with RADIUS authentication and a none fallback method. 12.2T based trains 12.3 based trains 12.3T based trains 12.4 based trains A system configured for RADIUS authentication and none fallback method will have a command line in show running-configuration output which is similar to the following . aaa authentication login xxxxxx group radius none (This is an affected configuration)aaa authentication ppp xxxxxx group radius none (This is an affected configuration)A system that is configured for RADIUS authentication with local and none fallback methods is also affected. An example to this configuration may look like similar to the following. aaa authentication login xxxxxx group radius local none (This is an affected configuration)aaa authentication ppp xxxxxx group radius local none (This is an affected configuration)A system is only vulnerable if none method is used as a fallback to RADIUS without any other method in between, or if only local method is used in between. Systems that are configured for RADIUS authentication with a fallback method other than local prior to none method are not affected. Refer to the Details section for more information about affected and unaffected configurations. Products Confirmed Not Vulnerable Products that are not running Cisco IOS are not affected. Products running Cisco IOS versions 12.1 and earlier (including 12.0S) and 12.2 mainline are not affected. Products that are running Cisco IOS are not affected unless they are configured for RADIUS authentication with a fallback method to none. No other Cisco products are currently known to be affected by this vulnerability. Details Authentication, Authorization, and Accounting (AAA) network security services provide the primary framework through which access control is set up on a device. AAA authentication services are used to control access to different services on a system. Multiple AAA authentication services can be configured on a system to fall back to a backup authentication method in case the primary authentication method is unavailable. AAA authentication can be used for different purposes (controlling access to the routers, authenticating remote subscribers etc.). Refer to the following URL for more information on AAA: http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fsecur_c/fsaaa/index.htm Remote Authentication Dial In User Service (RADIUS) is defined in RFC2865 and describes a protocol for carrying authentication, authorization, and configuration information. There is a vulnerability in AAA RADIUS authentication if none is used as a fallback method. Sending a sufficiently long username will bypass the RADIUS authentication and succeed. Following algorithm can be used to determine whether a configuration is vulnerable: 1. Are you using an affected version of IOS? No: You are not vulnerable. Yes: Go to step 2. 2. Is AAA RADIUS Authentication used? No: You are not vulnerable. Yes: Go to step 3. 3. Is none used as an alternative to RADIUS? No: You are not vulnerable. Yes: Go to step 4. 4. Is there any other method between RADIUS and none? No: You are vulnerable. Yes: Go to step 5. 5. Is the other authentication method local? No: You are not vulnerable. Yes: Go to step 4. Based on the algorithm above sample affected and unaffected configurations are given below. aaa authentication login xxxxxx group radius none (This is an affected configuration)aaa authentication login xxxxxx group radius local none (This is an affected configuration)aaa authentication login xxxxxx group radius group tacacs+ none (This is an unaffected configuration)aaa authentication login xxxxxx group radius enable none (This is an unaffected configuration)aaa authentication login xxxxxx group radius line none (This is an unaffected configuration)aaa authentication login xxxxxx group radius local line none (This is an unaffected configuration)Removing the none fallback method or putting at least one additional method other than local between RADIUS and none will mitigate this vulnerability. Impact Successful exploitation of the vulnerability may result in bypassing the RADIUS authentication. Software Versions and Fixes 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. 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). For further information on the terms "Rebuild" and "Maintenance, " please consult the following URL: http://www.cisco.com/warp/public/620/1.html Major Release Availability of Repaired Releases Affected 12.2-Based Release Rebuild Maintenance 12.2B Vulnerable; migrate to 12.3(11)T or later 12.2BC Vulnerable; migrate to 12.3(13)BC, available TBD 12.2BW Vulnerable; migrate to 12.3(10) or later 12.2BX Vulnerable; migrate to 12.3(7)XI6, available TBD 12.2BY Vulnerable; migrate to 12.3(11)T or later 12.2BZ Vulnerable; migrate to 12.3(7)XI6, available TBD 12.2CX Vulnerable; migrate to 12.3(13)BC, available TBD 12.2CY Vulnerable; migrate to 12.3(13)BC, available TBD 12.2CZ Vulnerable; contact TAC 12.2EW Vulnerable; migrate to 12.2(25)EWA2, available 7-July-05 12.2EWA 12.2(25)EWA2, available 7-July-05 12.2EY 12.2(25)EY2 12.2EZ Vulnerable; migrate to 12.2(25)SEC, available 21-July-05 12.2JA Vulnerable; migrate to 12.3(7)JA, available on 08-Aug-05 12.2JK Vulnerable; contact TAC 12.2MB Vulnerable; migrate to 12.2SW 12.2MC Vulnerable; migrate to 12.3(11)T or later 12.2MX Vulnerable; migrate to 12.3(11)T or later 12.2SE 12.2(25)SEB2 12.2(25)SEC, available 21-July-05 12.2SXD 12.2(18)SXD5 12.2SXE 12.2(18)SXE2, available 18-July-05 12.2T Vulnerable; migrate to 12.3 train 12.2XB Vulnerable; migrate to 12.3(10) or later 12.2XC Vulnerable; migrate to 12.3(11)T or later 12.2XD Vulnerable; migrate to 12.3(10) or later 12.2XE Vulnerable; migrate to 12.3(10) or later 12.2XF Vulnerable; migrate to 12.3(13)BC, available TBD 12.2XG Vulnerable; migrate to 12.3(10) or later 12.2XH Vulnerable; migrate to 12.3(10) or later 12.2XI Vulnerable; migrate to 12.3(10) or later 12.2XJ Vulnerable; migrate to 12.3(10) or later 12.2XK Vulnerable; migrate to 12.3(10) or later 12.2XL Vulnerable; migrate to 12.3(10) or later 12.2XM Vulnerable; migrate to 12.3(10) or later 12.2XQ Vulnerable; migrate to 12.3(10) or later 12.2XR/12.2(2)XR/12.2(4)XR Vulnerable; migrate to 12.3(10) or later 12.2XT Vulnerable; migrate to 12.3(10) or later 12.2XW Vulnerable; migrate to 12.3(10) or later 12.2YA Vulnerable; contact TAC 12.2YB Vulnerable; migrate to 12.3(10) or later 12.2YC Vulnerable; migrate to 12.3(10) or later 12.2YD Vulnerable; migrate to 12.3(11)T or later 12.2YF Vulnerable; migrate to 12.3(10) or later 12.2YG Vulnerable; migrate to 12.3(10) or later 12.2YH Vulnerable; migrate to 12.3(10) or later 12.2YJ Vulnerable; migrate to 12.3(10) or later 12.2YL Vulnerable; migrate to 12.3(11)T or later 12.2YM Vulnerable; migrate to 12.3(11)T or later 12.2YN Vulnerable; migrate to 12.3(11)T or later 12.2YP Vulnerable; migrate to 12.3(10) or later 12.2YQ Vulnerable; migrate to 12.3(11)T or later 12.2YR Vulnerable; migrate to 12.3(11)T or later 12.2YT Vulnerable; migrate to 12.3(10) or later 12.2YU Vulnerable; migrate to 12.3(11)T or later 12.2YV Vulnerable; migrate to 12.3(11)T or later 12.2YW Vulnerable; migrate to 12.3(11)T or later 12.2YY Vulnerable; migrate to 12.3(11)T or later 12.2ZB Vulnerable; migrate to 12.3(11)T or later 12.2ZC Vulnerable; migrate to 12.3(11)T or later 12.2ZD Vulnerable; migrate to 12.3(11)T or later 12.2ZE Vulnerable; migrate to 12.3(10) or later 12.2ZF Vulnerable; migrate to 12.3(11)T or later 12.2ZG Vulnerable; migrate to 12.3(11)T or later 12.2ZH Vulnerable; contact TAC 12.2ZJ Vulnerable; migrate to 12.3(11)T or later 12.2ZL Vulnerable; contact TAC 12.2ZN Vulnerable; migrate to 12.3(11)T or later 12.2ZO Vulnerable; migrate to 12.3(10) or later 12.2ZP Vulnerable; migrate to 12.3(11)T or later Affected 12.3-Based Release Rebuild Maintenance 12.3 12.3(10) 12.3B Vulnerable; migrate to 12.3(11)T or later 12.3BC 12.3(13)BC, available TBD 12.3BW Vulnerable; migrate to 12.3(11)T or later 12.3JA 12.3(7)JA, available on 08-Aug-05 12.3T 12.3(7)T11, available TBD 12.3(11) 12.3(8)T4 12.3XA Vulnerable; migrate to 12.3(11)T or later 12.3XB Vulnerable; migrate to 12.3(11)T or later 12.3XC Vulnerable; contact TAC 12.3XD Vulnerable; migrate to 12.3(11)T or later 12.3XE Vulnerable; migrate to 12.3(11)T or later 12.3XF Vulnerable; migrate to 12.3(11)T or later 12.3XG Vulnerable; migrate to 12.3(11)T or later 12.3XH Vulnerable; migrate to 12.3(11)T or later 12.3XI 12.3(7)XI6, available TBD 12.3XJ Vulnerable; migrate to 12.3(11)T or later 12.3XK Vulnerable; migrate to 12.3(14)T or later 12.3XL 12.3(11)XL 12.3XM Vulnerable; migrate to 12.3(14)T or later 12.3XN Vulnerable; migrate to 12.3(14)T or later 12.3XQ Vulnerable; migrate to 12.3(14)T or later 12.3XR Vulnerable; contact TAC 12.3XS Vulnerable; migrate to 12.3(14)T or later 12.3XT Vulnerable; contact TAC 12.3XU Vulnerable; contact TAC 12.3XW Vulnerable; migrate to 12.3(11)T or later 12.3XX Vulnerable; migrate to 12.3(14)T or later 12.3XY 12.3(8)XY5 12.3YA Vulnerable; migrate to 12.3(14)T or later 12.3YB Vulnerable; contact TAC 12.3YD 12.3(8)YD 12.3YF 12.3(11)YF 12.3YG 12.3(8)YG 12.3YH 12.3(8)YH 12.3YI 12.3(8)YI 12.3YJ 12.3(11)YJ 12.3YK 12.3(11)YK 12.3YL 12.3(11)YL 12.3YN 12.3(11)YN 12.3YR 12.3(11)YR 12.3YS 12.3(11)YS 12.3YQ 12.3(14)YQ Affected 12.4-Based Release Rebuild Maintenance 12.4 12.4(1) 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. 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. Removing none as a fallback to RADIUS or putting an additional method other than local between RADIUS and none will mitigate this vulnerability. For example, an affected system which has a configuration similar to the following aaa authentication login xxxxxx group radius none can be changed to one of the followingaaa authentication login xxxxxx group radius aaa authentication login xxxxxx group radius enable aaa authentication login xxxxxx group radius enable none aaa authentication login xxxxxx group radius line none as a workaround. Warning: Removing none as a fallback method may create problems if the RADIUS server becomes unavailable. With a none fallback in place, all authentication requests will succeed when the RADIUS server is unavailable. Removing none fallback method or replacing it with enable or another mechanism may result in authentication failure if RADIUS server becomes unavailable. 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-20050629-aaa.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.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 2005-July-1 Added 12.2XR/12.2(2)XR/12.2(4)XR to Software Version and Fixes Table. Updated 12.2T row. Revision 1.0 2005-Jun-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/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. -------------------------------------------------------------------------------- Updated: Jul 01, 2005 Document ID: 65328 [***** End Cisco Security Advisory Document ID: 65328 *****] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Cisco 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. LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC) P-227: Step-by-Step Interactive Training Vulnerability P-228: ISA Server 2000 Cumulative Update P-229: Vulnerability in Microsoft Agent Could Allow Spoofing (890046) P-230: Vulnerability in Telnet Client Could Allow Information Disclosure (896428) P-231: Security Vulnerability in the lpadmin(1M) Utility P-232: VERITAS Security Updates P-233: RealNetworks Security Update P-234: RealPlayer SMIL File Vulnerability P-235: FTPSERV.NLM Abend and Security fixes P-236: Adobe Reader and Acrobat Malicious PDF Document