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AUSCERT External Security Bulletin Redistribution
ESB-2008.0474 -- [Solaris]
Security Vulnerability in the TCP Implementation of Solaris Systems May
Allow a Denial of Service When Accepting New Connections
While Undergoing a TCP "SYN Flood" Attack
12 May 2008
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AusCERT Security Bulletin Summary
---------------------------------
Product: TCP Implementation
Publisher: Sun Microsystems
Operating System: Solaris
Impact: Denial of Service
Access: Remote/Unauthenticated
CVE Names: CVE-2008-2121
Original Bulletin:
http://sunsolve.sun.com/search/printfriendly.do?assetkey=1-66-200864-1
Revision History: May 12 2008: Added CVE reference
May 8 2008: Initial Release
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Solution Type: Sun Alert
Solution 200864 : Security Vulnerability in the TCP Implementation
of Solaris Systems May Allow a Denial of Service When Accepting New
Connections While Undergoing a TCP "SYN Flood" Attack
Bug ID: 6402737
Product
Solaris 8 Operating System,
Solaris 9 Operating System,
Solaris 10 Operating
System
Date of Resolved Release: 06-May-2008
SA Document Body
Security Vulnerability in the TCP Implementation of Solaris Systems May
Allow a Denial of Service When Accepting New Connections While Undergoing
a TCP "SYN Flood" Attack
1. Impact
A security vulnerability in the TCP implementation of Solaris 8, 9 and
10 may allow a remote unprivileged user to cause a Solaris system
which is undergoing a "TCP SYN" flood condition to be slow to accept
new network connections. Such network connections may time out
without establishing a connection. This would lead to a Denial of
Service (DoS) to the network services provided by that system. In
addition, a uniprocessor system may also experience overall slowdown
due to high CPU usage, resulting in a Denial of Service to the system
as a whole.
2. Contributing Factors
This issue can occur in the following releases:
SPARC Platform
* Solaris 8 without patch 116965-33
* Solaris 9 without patch 114344-35
* Solaris 10 without patch 119998-01
x86 Platform
* Solaris 8 without patch 116966-32
* Solaris 9 without patch 119435-23
* Solaris 10 without patch 119999-01
Notes:
1. This issue affects hosts which have a value for the ndd(1M)
tunable 'tcp_conn_req_max_q0' which is considerably higher than
the default value of 1024. The higher the value, the greater the
impact of this issue if it is exploited on a host.
To determine the value of the 'tcp_conn_req_max_q0' tunable, the
following command can be used:
$ ndd -get /dev/tcp tcp_conn_req_max_q0
1024
3. Symptoms
If this issue is exploited, the following message may be seen on the
console:
WARNING: High TCP connect timeout rate!
System (port <port number>) may be under a SYN flood attack
4. Workaround
To work around the described issue, make sure the value of the ndd(1M)
tunable 'tcp_conn_req_max_q0' for TCP is not much higher than the
default of 1024, using commands such as the following:
$ ndd -get /dev/tcp tcp_conn_req_max_q0
4000
$ ndd -set /dev/tcp tcp_conn_req_max_q0 1024
$ ndd -get /dev/tcp tcp_conn_req_max_q0
1024
5. Resolution
This issue is addressed in the following releases:
SPARC Platform
* Solaris 8 with patch116965-33 or later
* Solaris 9 with patch 114344-35 or later
* Solaris 10 with patch 119998-01 or later
x86 Platform
* Solaris 8 with patch 116966-32 or later
* Solaris 9 with patch 119435-23 or later
* Solaris 10 with patch 119999-01 or later
Note: There are additional Solaris 8 and 9 patches which list 6402737
in their README, however these patches are not required to address the
issue described in this Sun Alert. These additional patches deliver an
updated kernel debugger (kadb(1M)). The patch-IDs are:
SPARC Platform
* Solaris 8 patch 117350-54 or later
* Solaris 9 patch 122300-25 or later
x86 Platform
* Solaris 8 patch 117351-54 or later
* Solaris 9 patch 122301-25 or later
For more information on Security Sun Alerts, see Technical
Instruction ID 213557.
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 2000-2008 Sun Microsystems, Inc., 4150 Network Circle, Santa
Clara, CA 95054 U.S.A. All rights reserved
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