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Home : Advisories : Vulnerability in SGI login LOCKOUT

Title: Vulnerability in SGI login LOCKOUT
Released by: CERT
Date: 28th May 1997
Printable version: Click here

Hash: SHA1


CERT* Advisory CA-97.15

Original issue date: May 28, 1997

Last Revised: September 30, 1997

              Updated copyright statement

              A complete revision history is at the end of this file.

Topic: Vulnerability in SGI login LOCKOUT

- -----------------------------------------------------------------------------

   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.

- ---------------------------------------------------------------------------

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 http://www.first.org/team-info/)

CERT/CC Contact Information

- ----------------------------

Email    cert@cert.org

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


   In the subject line, type

        SUBSCRIBE  your-email-address

- ------------------------------------------------------------------------------

Copyright 1997 Carnegie Mellon University. Conditions for use, disclaimers,

and sponsorship information can be found in

http://www.cert.org/legal_stuff.html and http://ftp.cert.org/pub/legal_stuff .

If you do not have FTP or web access, send mail to cert@cert.org with

"copyright" in the subject line.

CERT is registered in the U.S. Patent and Trademark Office.

- ---------------------------------------------------------------------------

This file: http://info.cert.org/pub/cert_advisories/CA-97.15.sgi_login


               click on "CERT Advisories"



September 19, 1997

- ------------------

Silicon Graphics Inc. has issued Security Advisory, "IRIX LOCKOUT and

login/scheme Buffer Overrun" 19970508-02-PX, September 15, 1997.

This SGI advisory addresses the vulnerabilities discussed in the

following documents:

           AUSCERT AA-97.12 and CERT CA-97.15

           AUSCERT AA-97.22 and CERT CA-97.21

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.

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

Sept. 30, 1997  Updated copyright statement

Sept. 19, 1997  Updates Section. Added updated vendor information for

                Silicon Graphics, Inc.


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