AUSCERT External Security Bulletin Redistribution

              ESB-97.149 -- SGI Security Advisory 19971102-01-PX
                         Vulnerability in at(1) program
                              19 Novemeber 1997


Silicon Graphics Inc. has released the following advisory concerning a
vulnerability in the at(1) program.  Information regarding this
vulnerability has been previously described in CERT Advisory CA-97.18
(re-released as AUSCERT ESB-97.072 on June 13, 1997).  

This vulnerability may allow users with a local account to execute
commands with root privileges.

The following security bulletin is provided as a service to AUSCERT's
members.  As AUSCERT did not write this document, AUSCERT has had no
control over its content.  As such, the decision to use any or all of this
information is the responsibility of each user or organisation, and should
be done so in accordance with site policies and procedures.

NOTE: This is only the original release of the security bulletin.  It will
not be updated when the original bulletin is.  If downloading at a later
date, it is recommended that the bulletin is retrieved from the original
authors to ensure that the information is still current.

Contact information for SGI is included in the Security Bulletin
below.  If you have any questions or need further information, please
contact them directly.

Previous advisories and external security bulletins can be retrieved from:


If you believe that your system has been compromised, contact AUSCERT or your
representative in FIRST (Forum of Incident Response and Security Teams).

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 4477
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
	AUSCERT personnel answer during Queensland business hours
	which are GMT+10:00 (AEST).
	On call after hours for emergencies.

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                Silicon Graphics Inc. Security Advisory

        Title:   Vulnerability in at(1) program
        Title:   CERT CA-97.18
        Number:  19971102-01-PX
        Date:    November 18, 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 at(1) program is used by local users to read commands from standard
input to be executed at a later time.  These commands are run as the
user using the at(1) program.

In normal operation, the at(1) program runs as a setuid root privileged
program inorder to perform its tasks.  Unfortunately, a buffer overrun
has been discovered in the at(1) program which could allow arbitrary
commands to be run as the privileged user root.

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 at(1) program is installed on all Silicon Graphics IRIX systems by

A local account is required in order to exploit this vulnerability both
locally and remotely.

This vulnerability can be utilized to execute commands with root

This vulnerability has been publically discussed in Usenet newsgroups
and mailing lists and also reported in CERT Advisory CA-97.18.

- - --------------------------
- - --- 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 removing
the permissions of the at(1) program.

     1) Become the root user on the system.

                % /bin/su -

     2) Remove the permissions on the at(1) program.

                # /bin/chmod 0 /usr/bin/at

                           *** NOTE ***

               Removing the permissions from the at(1)
               program will prevent the program from
               executing, even for root user.

     3) 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          2225
   IRIX 6.0.x        yes          not avail    Note 1
   IRIX 6.1          yes          not avail    Note 1
   IRIX 6.2          yes          2230
   IRIX 6.3          yes          2232
   IRIX 6.4          yes          2233


     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 ( 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.2225
Algorithm #1 (sum -r):    17470 8 README.patch.2225
Algorithm #2 (sum):       32106 8 README.patch.2225
MD5 checksum:             42A1501001E07C40544C93859E7C6E1B

Filename:                 patchSG0002225
Algorithm #1 (sum -r):    12944 1 patchSG0002225
Algorithm #2 (sum):       30466 1 patchSG0002225
MD5 checksum:             C8158D7B6552684FB4B89949627F6CFC

Filename:                 patchSG0002225.eoe1_sw
Algorithm #1 (sum -r):    58136 49 patchSG0002225.eoe1_sw
Algorithm #2 (sum):       9067 49 patchSG0002225.eoe1_sw
MD5 checksum:             A97C10C3461E249585895CA72652A2E3

Filename:                 patchSG0002225.idb
Algorithm #1 (sum -r):    15748 1 patchSG0002225.idb
Algorithm #2 (sum):       34188 1 patchSG0002225.idb
MD5 checksum:             0B7C6DC178A5C327E53F875A113E1971

Filename:                 README.patch.2230
Algorithm #1 (sum -r):    58607 17 README.patch.2230
Algorithm #2 (sum):       35215 17 README.patch.2230
MD5 checksum:             4340DCE3BA3469941F1361BB6208EDB1

Filename:                 patchSG0002230
Algorithm #1 (sum -r):    46535 2 patchSG0002230
Algorithm #2 (sum):       5679 2 patchSG0002230
MD5 checksum:             945EC35A9340CF2A74721701589AE3EC

Filename:                 patchSG0002230.eoe_man
Algorithm #1 (sum -r):    34340 606 patchSG0002230.eoe_man
Algorithm #2 (sum):       28556 606 patchSG0002230.eoe_man
MD5 checksum:             83D6EF44CAE016B7C509A63A450E2EEA

Filename:                 patchSG0002230.eoe_sw
Algorithm #1 (sum -r):    21159 1954 patchSG0002230.eoe_sw
Algorithm #2 (sum):       52976 1954 patchSG0002230.eoe_sw
MD5 checksum:             E3CA682069D56992A92FC0B1385C8C6F

Filename:                 patchSG0002230.idb
Algorithm #1 (sum -r):    27782 15 patchSG0002230.idb
Algorithm #2 (sum):       1450 15 patchSG0002230.idb
MD5 checksum:             42654CBFA3AD648A9DBBDAA5C3115E31

Filename:                 README.patch.2232
Algorithm #1 (sum -r):    30727 12 README.patch.2232
Algorithm #2 (sum):       55743 12 README.patch.2232
MD5 checksum:             DD9402D2434B1513A3B9886D70CD9243

Filename:                 patchSG0002232
Algorithm #1 (sum -r):    55916 3 patchSG0002232
Algorithm #2 (sum):       20486 3 patchSG0002232
MD5 checksum:             FE63680542E429EA91D33AA15EB06537

Filename:                 patchSG0002232.eoe_man
Algorithm #1 (sum -r):    43804 36 patchSG0002232.eoe_man
Algorithm #2 (sum):       27383 36 patchSG0002232.eoe_man
MD5 checksum:             6EE21B2D5362295BDC20D5F84BA7DEC4

Filename:                 patchSG0002232.eoe_sw
Algorithm #1 (sum -r):    03690 421 patchSG0002232.eoe_sw
Algorithm #2 (sum):       11833 421 patchSG0002232.eoe_sw
MD5 checksum:             C5AD8C10999347F8FA67871B5B98CB63

Filename:                 patchSG0002232.idb
Algorithm #1 (sum -r):    38374 4 patchSG0002232.idb
Algorithm #2 (sum):       4337 4 patchSG0002232.idb
MD5 checksum:             0610B31450652A09F343E2B1ED3E939A

Filename:                 README.patch.2233
Algorithm #1 (sum -r):    51881 11 README.patch.2233
Algorithm #2 (sum):       41695 11 README.patch.2233
MD5 checksum:             5D7F90A9AE9F2A483059E6D8D08DF317

Filename:                 patch2233.pgp.and.chksums
Algorithm #1 (sum -r):    00000 0 patch2233.pgp.and.chksums
Algorithm #2 (sum):       0 0 patch2233.pgp.and.chksums
MD5 checksum:             D41D8CD98F00B204E9800998ECF8427E

Filename:                 patchSG0002233
Algorithm #1 (sum -r):    18405 3 patchSG0002233
Algorithm #2 (sum):       23610 3 patchSG0002233
MD5 checksum:             462695A8E5958C4B6A78960F001A2351

Filename:                 patchSG0002233.eoe_man
Algorithm #1 (sum -r):    43804 36 patchSG0002233.eoe_man
Algorithm #2 (sum):       27383 36 patchSG0002233.eoe_man
MD5 checksum:             6EE21B2D5362295BDC20D5F84BA7DEC4

Filename:                 patchSG0002233.eoe_sw
Algorithm #1 (sum -r):    24542 347 patchSG0002233.eoe_sw
Algorithm #2 (sum):       6782 347 patchSG0002233.eoe_sw
MD5 checksum:             B5D1408146E7B71B1F5A8290ABCF5A4F

Filename:                 patchSG0002233.idb
Algorithm #1 (sum -r):    50085 3 patchSG0002233.idb
Algorithm #2 (sum):       41850 3 patchSG0002233.idb
MD5 checksum:             B41E8A31941E47BD46682CFB4641882F

- - ------------------------
- - --- Acknowledgments ---
- - ------------------------

Silicon Graphics wishes to thank the CERT Coordination Center
for their assistance in this matter.

- - -----------------------------------------------------------
- - --- Silicon Graphics Inc. Security Information/Contacts ---
- - -----------------------------------------------------------

If there are questions about this document, email can be sent to


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 (  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/security.html.

For issues with the patches on the FTP sites, email can be sent to

For assistance obtaining or working with security patches, please
contact your SGI support provider.


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/security/wiretap.html) or by sending email
to SGI as outlined below.

% mail wiretap-request@sgi.com
subscribe wiretap <YourEmailAddress>

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.


Silicon Graphics provides a comprehensive customer World Wide Web site.
This site is located at http://www.sgi.com/Support/security/security.html.


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 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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