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From: SGI Security Coordinator <agent99 () boytoy ! csd ! sgi ! com>
Date: 1996-12-24 15:18:33
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Happy Holidays.
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-----BEGIN PGP SIGNED MESSAGE-----
______________________________________________________________________________
Silicon Graphics Inc. Security Advisory
Title: TCP SYN and Ping Denial of Service Attacks
Title: CERT(sm) Advisory CA-96.21, CERT(sm) Advisory
Title: CA-96.26, Silicon Graphics Advisory 19960901
Number: 19961202-01-PX
Date: December 24, 1996
______________________________________________________________________________
Silicon Graphics provides this information freely to the SGI user community
for its consideration, interpretation, implementation and use. Silicon
Graphics recommends that this information be acted upon as soon as possible.
Silicon Graphics will not be liable for any indirect, special, or
consequential damages arising from the use of, failure to use or improper
use of any of the instructions or information in this Security Advisory.
______________________________________________________________________________
- ------------------
- --- Background ---
- ------------------
In September of 1996, two alternative technical magazines published
articles expanding upon historical documents and discussions about
a possible "Denial of Service" (DoS) attack in the TCP/IP protocol. In
these recent magazine articles, actual code to accomplish a SYN Denial
of Service attack was provided. A SYN DoS attack uses a flood of SYN
TCP/IP packets to consume all available new network connections on a
targeted host. The result is that the system is delayed in responding
to new network connections and/or stops servicing requests altogether.
Later in October 1996, a public newsgroup discussion started regarding
a "fat ping" or "ping of death" DoS attack. This particular ping DoS
attack uses a ping packet of an abnormal size exceeding the TCP/IP
specification to either cause a system crash or network programs to
stop processing in the targeted host.
The very nature of these attacks are an abuse of the defined standards
for the TCP/IP protocol and these vulnerabilities exist, to some degree,
in the Silicon Graphics Inc. product line which uses the TCP/IP protocol
for networking.
Since any solutions to these issues could potentially effect TCP/IP
interoperability, system stability and performance, Silicon Graphics
worked closely with other TCP/IP product vendors, standards groups and
external security organizations such as CERT to ensure a proper solution.
- --------------
- --- Impact ---
- --------------
Silicon Graphics systems that are subject to a SYN DoS attack may
experience varying degrees of degradation in network response and
performance.
Silicon Graphics systems subject to a ping DoS attack, may under
certain circumstances panic and require a reboot.
The nature of both the SYN and ping DoS attacks allow for remote
exploitation without a local account on the targeted system.
Although a Denial of Service attack does not directly indicate that
a system has had a compromise, a Denial of Service attack could be
used to divert attention from actual intrusion activity.
Systems most likely to be attacked are hosts that are directly connected
to the Internet as firewalls or servers (web, FTP, telnet, etc).
- --------------------------------------
- --- Attack Detection and Reporting ---
- --------------------------------------
During normal operation, detecting a SYN attack may be difficult since
the attack only effects new incoming network connection attempts.
Existing incoming network connections as well, as outgoing connections
will continue to function properly.
If an attack is suspected, any user on the system can execute the
following command:
% /usr/etc/netstat -a -f inet
If a large number of the connections are in the state of "SYN_RECEIVED",
this is a possible indication of a SYN Denial of Service attack is
occurring. However, a large number of connections in "SYN_RECEIVED"
may be normal depending on the systems purpose and user base eg. webserver
for Internet Service Provider.
Detection of a ping attack, could be possible using a packet tracing
program and monitoring for ping and other packets of abnormally large
size.
Sites experiencing SYN or ping denial of services attacks should report
these attacks to the Computer Emergency Response Team/CERT(sm) Coordination
Center or the computer security response organization in your area.
The CERT(sm) Coordination Center can be contacted at:
CERT(sm) Coordination Center
Internet: cert@cert.org
Phone: +1 412 / 268-7090
FAX: +1 412 / 268-6989
http://www.cert.org/
- ----------------
- --- Solution ---
- ----------------
There are no interim solutions for these issues. The only solution
for these vulnerabilities is the installation of a patch.
**** IRIX 3.x ****
Silicon Graphics Inc, no longer supports the IRIX 3.x operating system
and therefore has no patches to provide.
**** IRIX 4.x ****
Silicon Graphics Inc, does not support patches for the IRIX 4.x
operating system. An upgrade to 5.3 or better is required first.
**** IRIX 5.0.x, 5.1.x, 5.2 ****
For the IRIX operating systems versions 5.0.x, 5.1.x, and 5.2 an upgrade
to 5.3 or better is required first. When the upgrade is completed,
then the patches described in the following sections can be applied
depending on the final version of the upgrade.
**** IRIX 5.3 ****
For the IRIX operating system version 5.3, an inst-able patch has
been generated and made available via anonymous FTP and your
service/support provider. The patch is number 1529 and will
install only on IRIX 5.3.
The SGI anonymous FTP site is sgigate.sgi.com (204.94.209.1) or its
mirror, ftp.sgi.com. Patch 1529 can be found in the following
directories on the FTP server:
~ftp/Security
or
~ftp/Patches/5.3
##### Checksums ####
The actual patch will be a tar file containing the following files:
Filename: README.patch.1529
Algorithm #1 (sum -r): 03188 44 README.patch.1529
Algorithm #2 (sum): 43063 44 README.patch.1529
MD5 checksum: 6F6BDE312ADA6CC86BCC23DA1F8CAC88
Filename: patchSG0001529
Algorithm #1 (sum -r): 04373 26 patchSG0001529
Algorithm #2 (sum): 32498 26 patchSG0001529
MD5 checksum: 5542FAF3D35A5D5A9E69EEFD240A323F
Filename: patchSG0001529.dev_hdr
Algorithm #1 (sum -r): 55046 18 patchSG0001529.dev_hdr
Algorithm #2 (sum): 21666 18 patchSG0001529.dev_hdr
MD5 checksum: 12D756C9AAADDA464F628FB08B8012C2
Filename: patchSG0001529.eoe1_man
Algorithm #1 (sum -r): 58486 19 patchSG0001529.eoe1_man
Algorithm #2 (sum): 19828 19 patchSG0001529.eoe1_man
MD5 checksum: 971A700918352743FDFAD9DC7AAC7F08
Filename: patchSG0001529.eoe1_sw
Algorithm #1 (sum -r): 61823 3751 patchSG0001529.eoe1_sw
Algorithm #2 (sum): 2250 3751 patchSG0001529.eoe1_sw
MD5 checksum: 622F1D1511C9806299C69FBC312B3412
Filename: patchSG0001529.eoe2_man
Algorithm #1 (sum -r): 20509 16 patchSG0001529.eoe2_man
Algorithm #2 (sum): 64242 16 patchSG0001529.eoe2_man
MD5 checksum: B0491FEFB0CE1C0BC03F7A1345BDE250
Filename: patchSG0001529.eoe2_sw
Algorithm #1 (sum -r): 22111 1384 patchSG0001529.eoe2_sw
Algorithm #2 (sum): 16791 1384 patchSG0001529.eoe2_sw
MD5 checksum: E6ACC9007CE438C9F2A0F2E05B8DE224
Filename: patchSG0001529.idb
Algorithm #1 (sum -r): 61507 45 patchSG0001529.idb
Algorithm #2 (sum): 6895 45 patchSG0001529.idb
MD5 checksum: F2ED426C3A80CB89B88F95EB73C0146C
Filename: patchSG0001529.nfs_man
Algorithm #1 (sum -r): 22345 17 patchSG0001529.nfs_man
Algorithm #2 (sum): 21111 17 patchSG0001529.nfs_man
MD5 checksum: 8782FA52CAB650472352DABC1C38B823
Filename: patchSG0001529.nfs_sw
Algorithm #1 (sum -r): 47185 162 patchSG0001529.nfs_sw
Algorithm #2 (sum): 59946 162 patchSG0001529.nfs_sw
MD5 checksum: 1C8543E58D67133B82CE1BD9FFCC7741
**** IRIX 6.0.x, 6.1 ****
For the IRIX operating system versions 6.0.x and 6.1, an upgrade
to 6.2 or better is required first. When the upgrade is completed,
then the security patches described in the following sections can be
applied depending on the final version of the upgrade.
**** IRIX 6.2 ****
For the IRIX operating system version 6.2, an inst-able patch has
been generated and made available via anonymous FTP and your
service/support provider. The patch is number 1418 and will
install only on IRIX 6.2.
The SGI anonymous FTP site is sgigate.sgi.com (204.94.209.1) or its
mirror, ftp.sgi.com. Patch 1418 can be found in the following
directories on the FTP server:
~ftp/Security
or
~ftp/Patches/6.2
##### Checksums ####
The actual patch will be a tar file containing the following files:
Filename: README.patch.1418
Algorithm #1 (sum -r): 08227 19 README.patch.1418
Algorithm #2 (sum): 7263 19 README.patch.1418
MD5 checksum: 2A29C3E6BD2BC36BC3FBBF7F84D32F85
Filename: patchSG0001418
Algorithm #1 (sum -r): 15567 3 patchSG0001418
Algorithm #2 (sum): 32384 3 patchSG0001418
MD5 checksum: 518F314AB6B434D4C176A99E26FEABC8
Filename: patchSG0001418.eoe_man
Algorithm #1 (sum -r): 46721 72 patchSG0001418.eoe_man
Algorithm #2 (sum): 55830 72 patchSG0001418.eoe_man
MD5 checksum: 5714CBC0D1E35DC6767CA2BB4BAC02F8
Filename: patchSG0001418.eoe_sw
Algorithm #1 (sum -r): 12616 5926 patchSG0001418.eoe_sw
Algorithm #2 (sum): 21075 5926 patchSG0001418.eoe_sw
MD5 checksum: 2081563727DE1A58B1C2DBEC54628CC7
Filename: patchSG0001418.idb
Algorithm #1 (sum -r): 22595 24 patchSG0001418.idb
Algorithm #2 (sum): 53385 24 patchSG0001418.idb
MD5 checksum: 90AD7C6B4114CE94E954CEFC332F0E4F
**** IRIX 6.3 (Early Access for O2) ****
IRIX operating system version 6.3 (Early Access for O2) is a limited
release version. An update to "IRIX 6.3 for O2 including R10000"
is required for this security issue. This security issue has
been addressed in the "IRIX 6.3 for O2 including R10000" distribution
which will go to all registered O2 customers.
**** IRIX 6.4 S2MP (Origin200, Origin2000, Onyx2) ****
IRIX operating system version 6.4 S2MP (Origin200, Origin2000, Onyx2)
is a limited release version. A future release of the IRIX 6.4
operating system will be released that will have corrections for
this issue. Customers with the limited release will receive
the future IRIX 6.4 release when it is available.
- ------------------------
- --- Acknowledgments ---
- ------------------------
Silicon Graphics wishes to thank the Unix vendor community, FIRST
members and CERT organizations worldwide for their assistance in this
matter.
- -----------------------------------------
- --- SGI Security Information/Contacts ---
- -----------------------------------------
If there are questions about this document, email can be sent to
cse-security-alert@csd.sgi.com.
------oOo------
Silicon Graphics provides security information and patches for
use by the entire SGI community. This information is freely
available to any person needing the information and is available
via anonymous FTP and the Web.
The primary SGI anonymous FTP site for security information and patches
is sgigate.sgi.com (204.94.209.1). Security information and patches
are located under the directories ~ftp/security and ~ftp/patches,
respectively. The Silicon Graphics Security Headquarters Web page is
accessible at the URL http://www.sgi.com/Support/Secur/security.html.
For issues with the patches on the FTP sites, email can be sent to
cse-security-alert@csd.sgi.com.
For assistance obtaining or working with security patches, please
contact your SGI support provider.
------oOo------
Silicon Graphics provides a free security mailing list service
called wiretap and encourages interested parties to self-subscribe
to receive (via email) all SGI Security Advisories when they are
released. Subscribing to the mailing list can be done via the Web
(http://www.sgi.com/Support/Secur/wiretap.html) or by sending email
to SGI as outlined below.
% mail wiretap-request@sgi.com
subscribe wiretap <YourEmailAddress>
end
^d
In the example above, <YourEmailAddress> is the email address that you
wish the mailing list information sent to. The word end must be on a
separate line to indicate the end of the body of the message. The
control-d (^d) is used to indicate to the mail program that you are
finished composing the mail message.
------oOo------
Silicon Graphics provides a comprehensive customer World Wide Web site.
This site is located at http://www.sgi.com/Support/Secur/security.html.
------oOo------
For reporting *NEW* SGI security issues, email can be sent to
security-alert@sgi.com or contact your SGI support provider. A
support contract is not required for submitting a security report.
______________________________________________________________________________
This information is provided freely to all interested parties and may
be additional distributed provided that it is not altered in any way,
Silicon Graphics is appropriately credited and the document retains
and includes its valid PGP signature.
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