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AUSCERT External Security Bulletin Redistribution
ESB-2005.0356 -- Sun Alert Notification 57746
Sun TCP Connections May Experience Performance Degradation
If Certain ICMP Error Messages Are Received
3 May 2005
AusCERT Security Bulletin Summary
Publisher: Sun Microsystems
Operating System: Solaris 10
Impact: Denial of Service
CVE Names: CAN-2004-0791 CAN-2004-0790
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Sun(sm) Alert Notification
* Sun Alert ID: 57746
* Synopsis: Sun TCP Connections May Experience Performance
Degradation If Certain ICMP Error Messages Are Received
* Category: Security
* Product: Solaris
* BugIDs: 5084452
* Avoidance: None
* State: Committed
* Date Released: 12-Apr-2005
* Date Closed:
* Date Modified:
This Sun Alert describes the Sun specific impact of the issues described
in the Internet-Draft (I-D) titled "ICMP attacks against TCP" written by
Fernando Gont. The I-D describes how TCP(7P) connections could be reset
and disconnected as a result of ICMP(7P) error messages. Solaris will not
drop established TCP connections based on ICMP errors. There is a
theoretical possibility that a TCP connection which is in the process of
being set up could be terminated before being established. However, there
is no risk of data corruption or compromise in this scenario.
The draft also describes ICMP messages which could impact the performance
of existing TCP connections. This issue affects all current versions of
Solaris and thus Sun plans on improving how ICMP errors are handled to
further mitigate the impact of such ICMP messages.
This issue is also described in the following documents:
IETF Internet Draft at
CERT Vulnerability Note VU#222750 at
CVEs CAN-2004-0790 at
CVEs CAN-2004-0791 at
2. Contributing Factors
This issue can occur in the following releases:
* Solaris 7
* Solaris 8
* Solaris 9
* Solaris 10
* Solaris 7
* Solaris 8
* Solaris 9
* Solaris 10
In order to verify if ICMP error messages are being sent to a specific
system on the network, a network monitoring tool such as snoop(1M) can be
used from either the specific system or another system on the same network.
The following command can be run (as "root"):
# snoop -o <output-file>
Afterwards, the snoop(1M) utility can display the packets captured in
the "output-file" using the "-v" and "-i" options, as in:
# snoop -v -i output-file icmp icmp6
and inspect the output for ICMP packets which will look similar to the
ICMP: ----- ICMP Header -----
ICMP: Type = 0 (Echo reply)
ICMP: Code = 0 (ID: 5417 Sequence number: 0)
ICMP: Checksum = be96
If the "Type" value and the "Code" value (for multiple packets) are
equal to any of the following combinations:
Type Code Name
---- ---- -----------------
4 0 Source Quench
3 * Net/Host/Protocol/Port Unreachable, etc.
5 * Redirect
6 0 Alternate Host Address
11 * Time Exceeded
12 * Parameter Problem
then the system may be the target of the described ICMP issue.
There is no workaround for this issue at this time.
A final resolution is pending completion.
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
notification may only be used for the purposes contemplated by these
Copyright 2000-2005 Sun Microsystems, Inc., 4150 Network Circle, Santa
Clara, CA 95054 U.S.A. All rights reserved.
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