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CERT* Advisory CA-97.15
Original issue date: May 28, 1997
Last revised: ---

Topic: Vulnerability in SGI login LOCKOUT

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   The text of this advisory was originally released on April 10, 1997, as
   AUSCERT Advisory AA-97.12, developed by the Australian Computer Emergency
   Response Team. To more widely broadcast this information, we are reprinting
   the AUSCERT advisory here with their permission. Only the contact
   information at the end has changed: AUSCERT contact information has been
   replaced with CERT/CC contact information.

   We will update this advisory as we receive additional information.
   Look for it in an "Updates" section at the end of the advisory.


AUSCERT has received information that a vulnerability exists in the login
program when the LOCKOUT parameter in /etc/default/login is set to a number
greater than zero. This vulnerability is known to be present in IRIX 5.3
and 6.2. Other versions of IRIX may also be vulnerable.

This vulnerability may allow users to create arbitrary or corrupt certain
files on the system.

Exploit information involving this vulnerability has been made publicly

At this stage, AUSCERT is unaware of any official vendor patches.  AUSCERT
recommends that sites apply the workaround given in Section 3 until vendor
patches are made available.

This advisory will be updated as more information becomes available.

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1.  Description

    Under the IRIX operating system, there is a file /etc/default/login
    which contains default security logging configuration options.  If
    the parameter LOCKOUT is included in this file, and is set to a value
    greater than zero, it causes accounts to be locked after a specified
    number of consecutive unsuccessful login attempts by the same user.

    When LOCKOUT is enabled users may be able to create arbitrary or
    corrupt certain files on the system, due to an inadequate check in
    the login verification process.

    Sites can determine if this functionality is enabled by using the

        % grep '^LOCKOUT' /etc/default/login

    If the number on the same line as LOCKOUT is greater than zero the
    vulnerability may be exploited.

    Information involving this vulnerability has been made publicly

    Silicon Graphics Inc. has informed AUSCERT that they are investigating
    this vulnerability.

2.  Impact

    Users may create arbitrary or corrupt certain files on the system.

3.  Workarounds/Solution

    AUSCERT recommends that sites prevent the exploitation of this
    vulnerability by immediately applying the workaround given in Section

    Currently there are no vendor patches available that address this
    vulnerability.  AUSCERT recommends that official vendor patches be
    installed when they are made available.

3.1 Disable the LOCKOUT parameter

    To prevent the exploitation of the vulnerability described in this
    advisory, AUSCERT recommends that the functionality provided with the
    LOCKOUT parameter be disabled.

    The LOCKOUT parameter can be disabled by editing /etc/default/login
    and commenting out the line containing the LOCKOUT parameter. The
    comment character for /etc/default/login is "#".

    Note that after applying this workaround, accounts will not be
    automatically locked using the LOCKOUT parameter functionality.

- ---------------------------------------------------------------------------
AUSCERT thanks to Alan J Rosenthal from The University of Toronto and
Silicon Graphics Inc. for their assistance in this matter.
- ---------------------------------------------------------------------------

If you believe that your system has been compromised, contact the CERT
Coordination Center or your representative in the Forum of Incident Response 
and Security Teams (see

CERT/CC Contact Information 
- ---------------------------- 
Email    This email address is being protected from spambots. You need JavaScript enabled to view it.

Phone    +1 412-268-7090 (24-hour hotline)
                CERT personnel answer 8:30-5:00 p.m. EST(GMT-5) / EDT(GMT-4)
                and are on call for emergencies during other hours.

Fax      +1 412-268-6989

Postal address
         CERT Coordination Center
         Software Engineering Institute
         Carnegie Mellon University
         Pittsburgh PA 15213-3890

Using encryption
   We strongly urge you to encrypt sensitive information sent by email. We can
   support a shared DES key or PGP. Contact the CERT/CC for more information. 
   Location of CERT PGP key

Getting security information
   CERT publications and other security information are available from

   CERT advisories and bulletins are also posted on the USENET newsgroup 

   To be added to our mailing list for advisories and bulletins, send 
   email to
        This email address is being protected from spambots. You need JavaScript enabled to view it. 
   In the subject line, type 
        SUBSCRIBE  your-email-address 

- ---------------------------------------------------------------------------
* Registered U.S. Patent and Trademark Office.

Copyright 1997 Carnegie Mellon University
This material may be reproduced and distributed without permission provided
it is used for noncommercial purposes and the copyright statement is

The CERT Coordination Center is part of the Software Engineering Institute
(SEI). The SEI is sponsored by the U.S. Department of Defense.
- ---------------------------------------------------------------------------

This file:
               click on "CERT Advisories"
May 28, 1997
- ------------
After the AUSCERT advisory was published, we received this information from
Silicon Graphics:

At this time, Silicon Graphics does not have any public information
for the login LOCKOUT issue.  Silicon Graphics has communicated with
CERT and other external security parties and is actively investigating
this issue.   When more Silicon Graphics information (including any
possible patches) is available for release, that information will
be released via the SGI security mailing list, wiretap.
For subscribing to the wiretap mailing list and other SGI security
related information, please refer to the Silicon Graphics Security
Headquarters website located at:


Revision history

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