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______________________________________________________________________________
Silicon Graphics Inc. Security Advisory
Title: talkd Vulnerability
Number: 19970701-01-PX
Date: July 23, 1997
______________________________________________________________________________
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 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
Silicon Graphics 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 ---
- -----------------------
The talkd(8) program is a support program for the user to user communications
program talk(1). As part of the start of talk communications between
two users, the talkd program obtains network hostname information from
DNS and then coordinates notifying users of a requested talk session.
A security vulnerability has been discovered in which manipulation of
provided network hostname information to the talkd program can be used
to execute arbitrary commands with root privileges.
Silicon Graphics Inc. has investigated the issue and recommends the
following steps for neutralizing the exposure. It is HIGHLY RECOMMENDED
that these measures be implemented on ALL SGI systems. This issue will
be corrected in future releases of IRIX.
- --------------
- --- Impact ---
- --------------
The talkd program (/usr/etc/talkd) is installed on all IRIX systems by
default.
For this particular vulnerability, a local account is not required.
Furthermore, the vulnerability can be exploited remotely.
This vulnerability can be utilized to execute commands with root
privileges.
This vulnerability has been public-ally discussed and reported in
AUSCERT advisory AA-97.01 and CERT advisory CA-97.04.
- --------------------------
- --- Temporary Solution ---
- --------------------------
Although patches are available for this issue, it is realized that
there may be situations where installing the patches immediately may
not be possible.
The steps below can be used to remove the vulnerability by disabling
the talkd program.
1) Become the root user on the system.
% /bin/su -
Password:
#
2) Edit the file /etc/inetd.conf . Place a "#" as
the first character of the talkd line to comment out
and deactivate the service.
# vi /usr/etc/inetd.conf
{Find the following line}
ntalk dgram udp wait root /usr/etc/talkd talkd
{Place a "#" as the first character of the ntalk line}
#ntalk dgram udp wait root /usr/etc/talkd talkd
{Save the file and exit}
3) Force inetd to re-read the configuration file.
# /etc/killall -HUP inetd
4) Return to previous level.
# exit
$
- ----------------
- --- Solution ---
- ----------------
OS Version Vulnerable? Patch # Other Actions
---------- ----------- ------- -------------
IRIX 3.x yes not avail Note 1
IRIX 4.x yes not avail Note 1
IRIX 5.0.x yes not avail Note 1
IRIX 5.1.x yes not avail Note 1
IRIX 5.2 yes not avail Note 1
IRIX 5.3 yes 2132
IRIX 6.0.x yes not avail Note 1
IRIX 6.1 yes not avail Note 1
IRIX 6.2 yes 2133
IRIX 6.3 yes 2133
IRIX 6.4 yes 2133
NOTES
1) upgrade operating system or see "Temporary Solution" section.
Patches are available via anonymous FTP and your service/support provider.
The SGI anonymous FTP site is sgigate.sgi.com (204.94.209.1) or its
mirror, ftp.sgi.com. Security information and patches can be found
in the ~ftp/security and ~ftp/patches directories, respectfully.
##### Patch File Checksums ####
The actual patch will be a tar file containing the following files:
Filename: README.patch.2132
Algorithm #1 (sum -r): 58795 8 README.patch.2132
Algorithm #2 (sum): 22126 8 README.patch.2132
MD5 checksum: 1C16F01A682CC8DB605DEC4C515B3ADD
Filename: patchSG0002132
Algorithm #1 (sum -r): 39922 1 patchSG0002132
Algorithm #2 (sum): 24988 1 patchSG0002132
MD5 checksum: 1BD1683D23D164F954BEE893B3CF8B2F
Filename: patchSG0002132.eoe2_sw
Algorithm #1 (sum -r): 29839 26 patchSG0002132.eoe2_sw
Algorithm #2 (sum): 636 26 patchSG0002132.eoe2_sw
MD5 checksum: EDB8C15F7D22F7104770D591952346E7
Filename: patchSG0002132.idb
Algorithm #1 (sum -r): 54227 1 patchSG0002132.idb
Algorithm #2 (sum): 34895 1 patchSG0002132.idb
MD5 checksum: 82E411637E20CB15E9EEFA3BA330F93D
Filename: README.patch.2133
Algorithm #1 (sum -r): 53634 8 README.patch.2133
Algorithm #2 (sum): 26859 8 README.patch.2133
MD5 checksum: 20FE236BEAC79EC8614BE84B5E291841
Filename: patchSG0002133
Algorithm #1 (sum -r): 05188 1 patchSG0002133
Algorithm #2 (sum): 27188 1 patchSG0002133
MD5 checksum: A4E881E9682DA41DE8897DE71D2EE42C
Filename: patchSG0002133.eoe_sw
Algorithm #1 (sum -r): 24652 27 patchSG0002133.eoe_sw
Algorithm #2 (sum): 6068 27 patchSG0002133.eoe_sw
MD5 checksum: 7ECC472AFE5105D195BCC2B75834D666
Filename: patchSG0002133.idb
Algorithm #1 (sum -r): 45369 1 patchSG0002133.idb
Algorithm #2 (sum): 35211 1 patchSG0002133.idb
MD5 checksum: 5BE2481FB3F325399BEE961AF0FB476C
- ------------------------
- --- Acknowledgments ---
- ------------------------
Silicon Graphics Inc. wishes to thank the CERT Coordination Center
and AUSCERT for their assistance in this issue.
- -----------------------------------------------------------
- --- Silicon Graphics Inc. Security Information/Contacts ---
- -----------------------------------------------------------
If there are questions about this document, email can be sent to
cse-security-alert@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/security.
For issues with the patches on the FTP sites, email can be sent to
cse-security-alert@sgi.com.
For assistance obtaining or working with security patches, please
contact your SGI support provider.
------oOo------
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------oOo------
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------oOo------
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______________________________________________________________________________
This information is provided freely to all interested parties and may
be redistributed 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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