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The U.S. Department of Energy
Computer Incident Advisory Capability
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INFORMATION BULLETIN
Cisco Catalyst Enable Password Bypass Vulnerability
April 25, 2003 21:00 GMT Number N-083
[REVISED May 8, 2003]
______________________________________________________________________________
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.
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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.
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LINKS:
CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/n-083.shtml
ORIGINAL BULLETIN:
http://www.cisco.com/warp/public/707/
cisco-sa-20030424-catos.shtml
______________________________________________________________________________
Revision 5/8/03: Workaround section, added information about AAA authentication
configurations.
[****** Start of Cisco Security Advisory ******]
Cisco Security Advisory: Cisco Catalyst Enable Password Bypass Vulnerability
Revision 1.3
Last Updated 2003 May 07 13:59 (GMT)
For Public Release 2003 April 24 08:00 (GMT)
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Please provide your feedback on this document.
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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
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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/tk583/tk642/
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 <address> <mask> telnet
set ip permit <address> <mask> 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.
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.
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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.
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[****** 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
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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
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