Bugtraq mailing list archives
[Fwd: Cisco Catalyst SSH Protocol Mismatch Vulnerability]
From: Kevin van der Raad <k.van.der.raad () itsec nl>
Date: Thu, 14 Dec 2000 17:05:37 +0100
We stumbled across the following, and wanted to share this with you: -- Cisco Catalyst SSH Protocol Mismatch Vulnerability Revision 1.0 For Public Release 2000 December 13 10:00 AM US/Pacific (UTC+0700) _________________________________________________________________ Summary Non-Secure Shell (SSH) connection attempts to an enabled SSH service on a Cisco Catalyst 6000, 5000, or 4000 switch might cause a "protocol mismatch" error, resulting in a supervisor engine failure. The supervisor engine failure causes the switch to fail to pass traffic and reboots the switch. This problem is resolved in release 6.1(1c). Due to a very limited number of customer downloads, Cisco has chosen to notify affected customers directly. This vulnerability has been assigned Cisco bug ID CSCds85763. The full text of this advisory can be viewed at: http://www.cisco.com/warp/public/707/catalyst-ssh-protocolmismatch-pub.shtml. Affected Products Catalyst 6000, 5000, 4000 images with SSH support. Version 6.1(1), 6.1(1a), 6.1(1b) with 3 Data Encryption Standard (DES) features only. Only the following images are affected: cat4000-k9.6-1-1.bin cat5000-sup3cvk9.6-1-1a.bin cat5000-sup3k9.6-1-1.bin cat5000-supgk9.6-1-1.bin cat6000-sup2cvk9.6-1-1b.bin cat6000-sup2k9.6-1-1b.bin cat6000-supcvk9.6-1-1b.bin cat6000-supk9.6-1-1b.bin Cisco IOS 12.1 SSH implementation is not affected by this vulnerability. No other Cisco devices are affected. Details Non SSH protocol connection attempts to the SSH service cause a "protocol mismatch" error, which causes a switch to reload. SSH is not enabled by default, and must be configured by the administrator. To verify if your image is affected, run the command "show version". If the image filename is listed above, and you have enabled SSH, you are affected by this vulnerability and should upgrade to a fixed version immediately. Impact This vulnerability enables a Denial of Service attack on the Catalyst switch. Software Versions and Fixes This defect is resolved in Cisco Catalyst version 6.1(1c). Previous affected versions will be deferred, and will no longer be available for customer download. Getting Fixed Software Cisco is offering free software upgrades to remedy this vulnerability for all affected customers. Customers with contracts should obtain upgraded software through their regular update channels. For most customers, this means that upgrades should be obtained via the Software Center on Cisco's Worldwide Web site at http://www.cisco.com. Customers without contracts 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 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 The workaround for this vulnerability is to disable SSH service. For most customers using this image, SSH support is necessary, so the recommended action is to upgrade to a fixed version. Exploitation and Public Announcements This vulnerability was reported to Cisco by a customer who discovered the issue during routine networking tests. There has been no public disclosure, and no reports of malicious activity with regard to this vulnerability. Status of This Notice: FINAL This is a final notice. Although Cisco cannot guarantee the accuracy of all statements in this notice, all of 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 is available on Cisco's Worldwide Web site at http://www.cisco.com/warp/public/707/catalyst-ssh-protocolmismatch-pub.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 recipients: cust-security-announce () cisco com Various internal Cisco mailing lists Specifically affected customers Future updates of this notice, if any, will be placed on Cisco's Worldwide Web server, but may or may not be actively announced on mailing lists or newsgroups. Users concerned about this problem are encouraged to check the URL given above for any updates. Revision History Revision 1.0 For public release 13-DEC-2000 10:00 AM US/Pacific (UTC+0700) 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 Web site at http://www.cisco.com/warp/public/707/sec_incident_response.shtml. This includes instructions for press inquiries regarding Cisco security notices. _________________________________________________________________ This notice is copyright 2000 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, including all date and version information. _________________________________________________________________ -- Kevin van der Raad <mailto:k.van.der.raad () itsec nl> ITsec Nederland B.V. <http://www.itsec.nl> Exploit & Vulnerability Alerting Service P.O. box 5120 NL 2000 GC Haarlem Tel +31(0)23 542 05 78 Fax +31(0)23 534 54 77 -- ITsec Nederland B.V. may not be held liable for the effects or damages caused by the direct or indirect use of the information or functionality provided by this posting, nor the content contained within. Use them at your own risk. ITsec Nederland B.V. bears no responsibility for misuse of this posting or any derivatives thereof.
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- [Fwd: Cisco Catalyst SSH Protocol Mismatch Vulnerability] Kevin van der Raad (Dec 16)