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AUSCERT External Security Bulletin Redistribution
ESB-2007.0391 -- [Solaris]
Security Vulnerability in the sshd(1M) Protocol Version 1 Implementation
May Allow a Denial of Service to the Host
2 July 2007
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AusCERT Security Bulletin Summary
---------------------------------
Product: sshd
Publisher: Sun Microsystems
Operating System: Solaris 10
Solaris 9
Impact: Denial of Service
Access: Remote/Unauthenticated
CVE Names: CVE-2006-4924
Ref: ESB-2006.0709
Original Bulletin:
http://sunsolve.sun.com/search/printfriendly.do?assetkey=1-26-102962-1
Revision History: July 2 2007: Patches released for Solaris 9
June 28 2007: Patches released for Solaris 10
June 11 2007: Initial Release
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Sun(sm) Alert Notification
* Sun Alert ID: 102962
* Synopsis: Security Vulnerability in the sshd(1M) Protocol Version
1 Implementation May Allow a Denial of Service to the Host
* Category: Security
* Product: Solaris 9 Operating System, Solaris 10 Operating System
* BugIDs: 6477720
* Avoidance: Patch, Workaround
* State: Resolved
* Date Released: 08-Jun-2007, 29-Jun-2007
* Date Closed: 29-Jun-2007
* Date Modified: 21-Jun-2007, 26-Jun-2007, 29-Jun-2007
1. Impact
A security vulnerability which affects the sshd(1M) daemon when
configured to use protocol version 1 may allow a remote user to cause
the daemon to consume an excessive amount of CPU power. This will
affect the performance and responsiveness of the system as a whole,
resulting in a denial of service (DoS) to the system.
This issue is also referenced in the following document:
CVE-2006-4924 at
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-4924
2. Contributing Factors
This issue can occur in the following releases:
SPARC Platform
* Solaris 9 without patch 113273-15
* Solaris 10 without patch 123324-03
x86 Platform
* Solaris 9 without patch 114858-12
* Solaris 10 without patch 123325-03
Notes:
1. Solaris 8 does not include the sshd(1M) daemon and is therefore
not impacted by this issue.
2. This issue only affects systems which are configured to run the
SSH service with version 1 of the SSH protocol.
A command such as the following can be used to determine if the sshd
daemon is running on a host:
$ pgrep sshd || echo "sshd not running"
To determine if sshd is configured to use version 1 of the protocol, a
command such as the following can be used to list the configured
protocols from the default configuration file (see sshd_config(4)):
$ grep Protocol /etc/ssh/sshd_config
Protocol 2,1
If '1' is included in the list of configured protocols (or if no
'Protocol' line is found as the default setting is '2,1'), then the
host is potentially affected by this issue; note that in order for
protocol version 1 to be truly supported on the host it must be
provided with a compatible host key via the HostKey directive, see
sshd_config(4) for more details.
3. Symptoms
If this issue is exploited to cause a denial of service on the host,
one or more sshd processes will be running and will be consuming an
unusually large percentage of CPU time. In addition, the host itself
may be generally unresponsive.
To determine the CPU usage of the processes running on the system, a
command such as the following can be used, which will sort the running
process by CPU consumption (in descending order):
$ prstat -s cpu
[...]
4. Relief/Workaround
To work around the described issue, sites may choose to disable
version 1 of the protocol by removing '1' from the list of supported
protocols in the /etc/ssh/sshd_config file (see sshd_config(4)). E.g.:
$ grep Protocol /etc/ssh/sshd_config
Protocol 2
and then restart the sshd daemon:
For Solaris 9:
# /etc/init.d/sshd stop ; /etc/init.d/sshd start
For Solaris 10:
# svcadm restart ssh
5. Resolution
This issue is addressed in the following releases:
SPARC Platform
* Solaris 9 with patch 113273-15 or later
* Solaris 10 with patch 123324-03 or later
x86 Platform
* Solaris 9 with patch 114858-12 or later
* Solaris 10 with patch 123325-03 or later
Change History
21-Jun-2007:
* Updated Contributing Factors and Resolution sections
26-Jun-2007:
* Updated Contributing Factors and Resolution sections
29-Jun-2007:
* Updated Contributing Factors and Resolution sections
* State: Resolved
This Sun Alert notification is being provided to you on an "AS IS"
basis. This Sun Alert notification may contain information provided by
third parties. The issues described in this Sun Alert notification may
or may not impact your system(s). Sun makes no representations,
warranties, or guarantees as to the information contained herein. ANY
AND ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR
NON-INFRINGEMENT, ARE HEREBY DISCLAIMED. BY ACCESSING THIS DOCUMENT
YOU ACKNOWLEDGE THAT SUN SHALL IN NO EVENT BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES THAT ARISE
OUT OF YOUR USE OR FAILURE TO USE THE INFORMATION CONTAINED HEREIN.
This Sun Alert notification contains Sun proprietary and confidential
information. It is being provided to you pursuant to the provisions of
your agreement to purchase services from Sun, or, if you do not have
such an agreement, the Sun.com Terms of Use. This Sun Alert
notification may only be used for the purposes contemplated by these
agreements.
Copyright 2000-2006 Sun Microsystems, Inc., 4150 Network Circle, Santa
Clara, CA 95054 U.S.A. All rights reserved
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