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______________________________________________________________________________
SGI Security Advisory
Title: IRIX TCP/IP Initial Sequence Numbers
Number: 20020303-01-A
Date: March 19, 2002
Reference: CERT CA-2001-09
Reference: SGI Security Advisory 19950123-02-I
Reference: SGI Security Advisory 19961202-01-PX
Reference: CERT CA-1996-21
Reference: CERT CA-1995-01
______________________________________________________________________________
SGI provides this information freely to the SGI user community for its
consideration, interpretation, implementation and use. SGI recommends
that this information be acted upon as soon as possible.
SGI provides the information in this Security Advisory on an "AS-IS" basis
only, and disclaims all warranties with respect thereto, express, implied
or otherwise, including, without limitation, any warranty of merchantability
or fitness for a particular purpose. In no event shall SGI be liable for
any loss of profits, loss of business, loss of data or for any indirect,
special, exemplary, incidental or consequential damages of any kind arising
from your use of, failure to use or improper use of any of the instructions
or information in this Security Advisory.
______________________________________________________________________________
- -----------------------
- --- Issue Specifics ---
- -----------------------
As part of on going security efforts, SGI acknowledges the "statistical
weaknesses in TCP/IP initial sequence numbers" vulnerability issue and
is investigating.
This was reported by Tim Newsham of Guardent and CERT:
http://www.cert.org/advisories/CA-2001-09.html
No further information is available at this time.
For the protection of all our customers, SGI does not disclose, discuss
or confirm vulnerabilities until a full investigation has occurred and
any necessary fixes are available for all vulnerable and supported IRIX
operating systems.
Until SGI has more definitive information to provide, customers are
encouraged to assume all security vulnerabilities as exploitable and take
appropriate steps according to local site security policies and requirements.
As further information becomes available, additional advisories will be
issued via the normal SGI security information distribution methods
including the wiretap mailing list.
- --------------------------
- --- Temporary Solution ---
- --------------------------
SGI has been tracking TCP ISN randomization issues over the years.
For details please see the following security advisories:
SGI Advisory 19950123-02-I
ftp://patches.sgi.com/support/free/security/advisories/19950123-02-I
CERT CA-1996-21
http://www.cert.org/advisories/CA-1996-21.html
SGI Advisory 19961202-01-PX
ftp://patches.sgi.com/support/free/security/advisories/19961202-01-PX
CERT CA-1995-01
http://www.cert.org/advisories/CA-1995-01.html
Thus far, SGI has implemented RFC 1948 with MD5 on IRIX 6.5.3 and
above using the tcpiss_md5 tunable kernel parameter. The default is
disabled.
To enable the tcpiss_md5 kernel parameter, perform the following
command as root:
# /usr/sbin/systune -b tcpiss_md5 1
To verify RFC 1948 has been enabled in IRIX, use the following command
as root:
# /usr/sbin/systune tcpiss_md5
This should return:
tcpiss_md5 = 1 (0x1)
SGI is investigating if more work in this area is needed beyond setting
tcpiss_md5=1 to fully address all issues presented in the CERT advisory.
- -------------------
- --- Information ---
- -------------------
SGI Security Advisories can be found at:
http://www.sgi.com/support/security/ and
ftp://patches.sgi.com/support/free/security/advisories/
SGI Security Patches can be found at:
http://www.sgi.com/support/security/ and
ftp://patches.sgi.com/support/free/security/patches/
SGI patches for IRIX can be found at the following patch servers:
http://support.sgi.com/irix/ and ftp://patches.sgi.com/
SGI freeware updates for IRIX can be found at:
http://freeware.sgi.com/
SGI fixes for SGI open sourced code can be found on:
http://oss.sgi.com/projects/
SGI patches and RPMs for Linux can be found at:
http://support.sgi.com/linux/ or
http://oss.sgi.com/projects/sgilinux-combined/download/security-fixes/
SGI patches for Windows NT or 2000 can be found at:
http://support.sgi.com/nt/
IRIX 5.2-6.4 Recommended/Required Patch Sets can be found at:
http://support.sgi.com/irix/ and ftp://patches.sgi.com/support/patchset/
IRIX 6.5 Maintenance Release Streams can be found at:
http://support.sgi.com/colls/patches/tools/relstream/index.html
IRIX 6.5 Software Update CDs can be obtained from:
http://support.sgi.com/irix/swupdates/
The primary SGI anonymous FTP site for security advisories and patches is
patches.sgi.com (216.32.174.211). Security advisories and patches are
located under the URL ftp://patches.sgi.com/support/free/security/
For security and patch management reasons, ftp.sgi.com (mirrors
patches.sgi.com security FTP repository) lags behind and does not do a
real-time update.
- ------------------------
- --- Acknowledgments ----
- ------------------------
SGI wishes to thank Tim Newsham, Guardent, CERT, and the members of
the Internet Community at large for their assistance in this matter.
- -----------------------------------------
- --- SGI Security Information/Contacts ---
- -----------------------------------------
If there are questions about this document, email can be sent to
security-info@sgi.com.
------oOo------
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------oOo------
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______________________________________________________________________________
This information is provided freely to all interested parties
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