__________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Cisco Catalyst Enable Password Bypass Vulnerability April 25, 2003 21:00 GMT Number N-083 [REVISED May 8, 2003] [REVISED Jan 6, 2005] ______________________________________________________________________________ PROBLEM: Cisco Catalyst software permits unauthorized access to the enable mode. Once initial access is granted, access can be obtained for the higher level "enable" mode without a password. PLATFORM: Cisco Catalyst 4000, 6000, and 6500 with the Catalyst OS software version 7.5(1) only. DAMAGE: This vulnerability permits unauthorized access to the configuration mode and unauthorized configuration changes on a Catalyst switch. SOLUTION: Apply workaround or upgrade as stated in Cisco's advisory. ______________________________________________________________________________ VULNERABILITY The risk is MEDIUM. Command line access is provided through the ASSESSMENT: console, telnet, or ssh. Therefore, anyone who can obtain command line access to an affected switch can bypass password authentication to obtain "enable" mode access without knowledge of the "enable" password. ______________________________________________________________________________ LINKS: CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/n-083.shtml ORIGINAL BULLETIN: Cisco Security Advisory Document ID: 42340 http://www.cisco.com/warp/public/707/ cisco-sa-20030424-catos.shtml ______________________________________________________________________________ Revision 5/8/03: Workaround section, added information about AAA authentication configurations. Revision 1/6/05: Updated URL for the Configuring TACACS+, RADIUS, and Kerberos on Cisco Catalyst Switches document, found in the Workarounds section of Cisco Document ID: 42340 (below). [****** Start of Cisco Security Advisory ******] Cisco Security Advisory: Cisco Catalyst Enable Password Bypass Vulnerability Revision 1.4 Last Updated 2005 January 05 23:15 (GMT) For Public Release 2003 April 24 08:00 (GMT) -------------------------------------------------------------------------------- Please provide your feedback on this document. -------------------------------------------------------------------------------- Contents Summary Affected Products Details Impact Software Versions and Fixes Obtaining Fixed Software Workarounds Exploitation and Public Announcements Status of This Notice Distribution Revision History Cisco Security Procedures -------------------------------------------------------------------------------- Summary Cisco Catalyst software permits unauthorized access to the enable mode in the 7.5(1) release. Once initial access is granted, access can be obtained for the higher level "enable" mode without a password. This problem is resolved in version 7.6(1). Customers with vulnerable releases are urged to upgrade as soon as possible. This issue is documented in Cisco Bug ID CSCea42030. This advisory is available at http://www.cisco.com/warp/public/707/ cisco-sa-20030424-catos.shtml. Affected Products All users of Cisco Catalyst 4000, 6000, and 6500 with the Catalyst OS software version 7.5(1) only. No other releases of Cisco Catalyst OS software are affected by this vulnerability. Additionally, Catalyst hardware running Cisco IOSŪ software is not affected by this vulnerability. No other Cisco products are affected by this vulnerability. Details Anyone who can obtain command line access to an affected switch can bypass password authentication to obtain "enable" mode access without knowledge of the "enable" password. If local user authentication is enabled, a valid username can be used to gain access to the switch without a valid password. This same local user could then enter enable without a valid password. Command line access is provided through the console, telnet access, or ssh access methods; http access mode is not affected. This problem was introduced with the local user authentication feature in software version 7.5(1), and is corrected in version 7.6(1). Bug ID CSCea42030 Impact This vulnerability permits unauthorized access to the configuration mode and unauthorized configuration changes on a Catalyst switch. Software Versions and Fixes This vulnerability is repaired in version 7.6(1) which is currently available. Obtaining Fixed Software Cisco is offering free software upgrades to remedy this vulnerability for all affected customers. Customers may only install and expect support for the feature sets they have purchased. 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 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 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) * email: tac@cisco.com. 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. 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 Workarounds Use of AAA authentication configurations will eliminate this vulnerability unless configured for fallback to local authentication. AAA configuration information and examples are provided in the following technical note: http://www.cisco.com/en/US/tech/tk59/technologies_tech_note09186a0080094ea4.shtml. Strictly limiting telnet and/or ssh access to the device will prevent the initial connection required to exploit this vulnerability. Telnet and/or ssh access can be controlled with the following command set: set ip permit
telnet set ip permit
ssh set ip permit enable This command set will deny all traffic not specified in the permit statements for each protocol. Additionally, out-of-band management solutions, isolated management VLAN configurations, and AAA authentication services can help mitigate this vulnerability by limiting the initial access necessary for exploitation. Exploitation and Public Announcements The Cisco PSIRT is not aware of any public announcements or malicious use of the vulnerabilities described in this advisory. This issue was reported to Cisco by a customer. Status of This Notice: Final This is a final notice. Although Cisco cannot guarantee the accuracy of all statements in this notice, all the facts have been checked to the best of our ability. Cisco does not anticipate issuing updated versions of this notice unless there is some material change in the facts. Should there be a significant change in the facts, Cisco may update this notice. Distribution This notice will be posted on Cisco's worldwide website at http://www.cisco.com/warp/public/707/cisco-sa-20030424-catos.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 * bugtraq@securityfocus.com * full-disclosure@lists.netsys.com * first-teams@first.org (includes CERT/CC) * cisco@spot.colorado.edu * cisco-nsp@puck.nether.net * comp.dcom.sys.cisco * Various internal Cisco mailing lists Future updates of this notice, if any, will be placed on Cisco's worldwide web. Users concerned about this problem are encouraged to check the URL given above for any updates. Revision History Revision 1.0 24-April-2003 Initial public release. Revision 1.1 24-April 2003 Added clarification under "Exploitation and Public Announcements" section. Revision 1.3 07-May-2003 Added link to AAA configuration examples. Revision 1.4 - January 2005. Updated the Configuring TACACS+, RADIUS, and Kerberos on Cisco Catalyst Switches document URL in the Workarounds section. 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/warp/public/707/sec_incident_response.shtml. This includes instructions for press inquiries regarding Cisco security notices. All Cisco Security Advisories are available at http://www.cisco.com/go/psirt. -------------------------------------------------------------------------------- This notice is Copyright 2003 by Cisco Systems, Inc. This notice may be redistributed freely after the release date given at the top of the text, provided that redistributed copies are complete and unmodified, and include all date and version information. -------------------------------------------------------------------------------- [****** End of Cisco Security Advisory ******] _______________________________________________________________________________ CIAC wishes to acknowledge the contributions of Cisco Systems, Inc. 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. 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