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| From: | CISCO | | Date: | 17.09.2003 | | Subject: | Cisco Security Advisory: OpenSSH Server Vulnerabilities |
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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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