Cisco Security Advisory: OpenSSH Server Vulnerabilities

2003-09-17T00:00:00
ID SECURITYVULNS:DOC:5125
Type securityvulns
Reporter Securityvulns
Modified 2003-09-17T00:00:00

Description

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        Cisco Security Advisory: OpenSSH Server Vulnerabilities

Revision Numeral: 1.0 INTERIM

For Public Release 2003 September 17 0700 GMT

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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: INTERIM
 Distribution
 Revision History
 Cisco Security Procedures

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Summary

New vulnerabilities in the OpenSSH leavingcisco.com implementation for SSH servers have been announced.

An affected network device, running an SSH server based on the OpenSSH implementation, may be vulnerable to a Denial of Service (DoS) attack when an exploit script is repeatedly executed against the same device. There are workarounds available to mitigate the effects of these vulnerabilities.

This advisory will be posted at http://www.cisco.com/warp/public/707/cisco-sa-20030917-openssh.shtml.

Affected Products

The following products, have their SSH server implementation based on the OpenSSH code, and are affected by the OpenSSH vulnerabilities.

 * Cisco Catalyst Switching Software (CatOS)

 * CiscoWorks 1105 Hosting Solution Engine (HSE)

 * CiscoWorks 1105 Wireless LAN Solution Engine (WLSE)

 * Cisco SN 5428 Storage Router

   Vulnerable versions are:

      * SN5428-2.5.1-K9

      * SN5428-3.2.1-K9

      * SN5428-3.2.2-K9

      * SN5428-3.3.1-K9

      * SN5428-3.3.2-K9

      * SN5428-2-3.3.1-K9

      * SN5428-2-3.3.2-K9

This does not include release sr2122-3.1.1-K9, which only contains SSL and no SSH. Cisco has not released code with SSH for the SN5420 storage router.

The following products, which incorporate a SSH server, have been confirmed to be not vulnerable to the OpenSSH vulnerabilities.

 * Cisco IOS, both SSH version 1.5 and SSH version 2.0

 * Cisco PIX Firewall

 * Cisco Catalyst 6000 FireWall Service Module (FWSM)

 * Cisco VPN3000 and Cisco VPN5000

No other Cisco products are currently known to be affected by these vulnerabilities.

Details

The buffer size or the number of channels in the fixed code is now correctly incremented only after a successful allocation where as initially they were being set before an allocation. Upon an allocation failure, which could be externally triggered, memory contents would be incorrectly erased by the cleanup process. This would result in a corruption of the memory which would eventually lead to a crash for the process using that memory.

The OpenSSH code diffs can be viewed at http://www.openssh.com/txt/buffer.adv leavingcisco.com.

Please note, the SSH server code under Cisco IOS has other vulnerabilities as documented by http://www.cisco.com/warp/public/707/ssh-packet-suite-vuln.shtml which may be triggered by the code written to exploit the OpenSHH vulnerabilities.

Cisco Catalyst Switching Software (CatOS)-This vulnerability is documented as Bug ID CSCecxxxxx. To be determined.

CiscoWorks 1105 Hosting Solution Engine (HSE)-This vulnerability is documented as Bug ID CSCecxxxxx. To be determined.

CiscoWorks 1105 Wireless LAN Solution Engine (WLSE)-This vulnerability is documented as Bug ID CSCecxxxxx. To be determined.

Cisco SN 5428 Storage Router-This vulnerability is documented as Bug ID CSCec32301 (registered customers only) . For more information on the SN 5428 please refer to http://www.cisco.com/en/US/products/hw/ps4159/ps2160/index.html.

Impact

An affected device, running an SSH server based on the OpenSSH implementation, may be vulnerable to a DoS attack when an exploit script is repeatedly executed against the same device.

Software Versions and Fixes

Cisco Catalyst Switching Software (CatOS)-To be determined.

CiscoWorks 1105 Hosting Solution Engine (HSE)-To be determined.

CiscoWorks 1105 Wireless LAN Solution Engine (WLSE)-To be determined.

Cisco SN 5428 Storage Router-Version 3.4.1, will incorporate this patch and will be available soon for the SN 5428, SN 5428-2, and the HP SR2122 (SN 5422).

Obtaining Fixed Software

Cisco is offering free software upgrades or patches to address these vulnerabilities for all affected customers. Customers may only install and expect support for the feature sets they have purchased. By installing, downloading, accessing or otherwise using such software upgrades or patches, 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 the Cisco Connection Online Software Center at http://www.cisco.com/public/sw-center/sw-usingswc.shtml.

Customers with service contracts should contact their regular update channels to obtain the free software upgrade(s) or patches identified via this advisory. For most customers with service contracts, this means that upgrades should be obtained through the Software Center on Cisco's worldwide website at http://www.cisco.com/tacpage/sw-center/. To access the software download URL, you must be a registered user and you must be logged in.

Customers whose Cisco products are provided or maintained through a 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 obtaining the free software upgrade(s).

Customers who purchased directly 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 obtain fixed software by contacting the Cisco Technical Assistance Center (TAC) using the contact information listed below. In these cases, customers are entitled to obtain an upgrade to a later version of the same release or as indicated by the applicable corrected software version in the Software Versions and Fixes section (noted above).

 * +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

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

The Cisco PSIRT recommends that affected users upgrade to a fixed software version of code as soon as it is available.

 * Restrict access to SSH server on the network device: Allow access to
   the network device only from trusted workstations by using ACL's / MAC
   filters that are available on the affected platforms.

 * As per best practices, if possible, ensure that the SSH server does
   not run on the default port of TCP 22 and is running on port higher
   than 1024 on critical network devices. This will prevent automated
   scanners from successfully exploiting this vulnerability.

Exploitation and Public Announcements

The Cisco PSIRT is not aware of any malicious use of the vulnerabilities described in this advisory, at this time.

These vulnerabilities have also been documented by CERT/CC at http://www.cert.org/advisories/CA-2003-24.html leavingcisco.com.

Status of This Notice: INTERIM

This is an interim advisory. Although Cisco cannot guarantee the accuracy of all statements in this advisory, all of the facts have been checked to the best of our ability. Cisco does not anticipate issuing updated versions of this advisory unless there is some material change in the facts. Should there be a significant change in the facts, Cisco may update this advisory.

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-20030917-openssh.shtml.

In addition to worldwide website posting, a text version of this advisory is clear-signed with the Cisco PSIRT PGP key having the fingerprint 8C82 5207 0CA9 ED40 1DD2 EE2A 7B31 A8CF 32B6 B590 and is posted to the following e-mail and Usenet news recipients:

 * cust-security-announce@cisco.com

 * bugtraq@securityfocus.com

 * first-teams@first.org (includes CERT/CC)

 * 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|2003-September-17|Initial public | |1.0 | |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/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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