Conference minotr::security_advisory

147.0. "Information Only: CERT CA-97.15, SGI login LOCKOUT" by MINOTR::NOBLE (Your Data, Your Job...Protect Both) Thu May 29 1997 08:30

    The DIGITAL Corporate Information Security Group has received the
    following external security notice.  It should be noted that DIGITAL
    does not support the software identified, nor have the reported
    problems been verified by DIGITAL.
    
    This third party notice is being provided as information only.  No
    security action is required.  Nor is any recommendation being made with
    regards the solution(s) identified.
    
    Should you happen to be using the third party software impacted by
    this notice, please use due discretion before implementing any or all
    of the solution(s) identified.
    
    If you are an internal user of the software impacted in this notice,
    and have any questions regarding this notice, then please contact your
    IT Cluster Security Manager.  An up-to-date list can be found at URL
    http://www-is-security.mso.dec.com/
      
                                  -=<>=-
    

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

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
available.

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
    command:

        % grep '^LOCKOUT' /etc/default/login
        LOCKOUT=3

    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
    available.

    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
    3.1.

    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.
- ---------------------------------------------------------------------------
===============================================================================

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* 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
included.

The CERT Coordination Center is part of the Software Engineering Institute
(SEI). The SEI is sponsored by the U.S. Department of Defense.
    
==========================================================================
    
UPDATES
 
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:
 
        http://www.sgi.com/Support/Secur/security.html
 

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