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_____________________________________________________________________________

                          SGI Security Advisory

        Title:      IRIX nsd symlink vulnerability
        Number:     20020501-01-I
        Date:       May 1, 2002
        Reference:  CAN-2002-0174
______________________________________________________________________________

- -----------------------
- --- Issue Specifics ---
- -----------------------

It has been reported that nsd was not checking the permissions and ownership
of its dump file "/var/tmp/nsd.dump" prior to writing to it.  

If a user was to first create a symlink from another file pointing to
/var/tmp/nsd.dump and then an already-privileged user sent a USR1 signal to
the nsd process, the file could be damaged or modified. If successfully
exploited, this could lead to a root compromise.

SGI has investigated the issue and recommends the following steps for
neutralizing the exposure.  It is HIGHLY RECOMMENDED that these measures be
implemented on ALL vulnerable SGI systems.


- --------------
- --- Impact ---
- --------------

The nsd daemon is installed by default on IRIX 6.5 systems as part of
eoe.sw.base.

This vulnerability may not be exploited by a remote user, a local account
is required.

This vulnerability has been fixed in IRIX 6.5.11.

This vulnerability was assigned the following CVE:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2002-0174


- ----------------------------
- --- Temporary Workaround ---
- ----------------------------

There is no effective workaround for this problem.  SGI's recommendation 
is to upgrade to IRIX 6.5.11 or later.


- ----------------
- --- Solution ---
- ----------------

SGI has not provided patches for this vulnerability. Our recommendation is
to upgrade to IRIX 6.5.11 or later.


   OS Version     Vulnerable?     Patch #      Other Actions
   ----------     -----------     -------      -------------    
   IRIX 3.x        unknown                     Note 1
   IRIX 4.x        unknown                     Note 1
   IRIX 5.x        unknown                     Note 1
   IRIX 6.0.x      unknown                     Note 1          
   IRIX 6.1        unknown                     Note 1         
   IRIX 6.2        unknown                     Note 1
   IRIX 6.3        unknown                     Note 1
   IRIX 6.4        unknown                     Note 1
   IRIX 6.5          yes                       Notes 2 & 3
   IRIX 6.5.1        yes                       Notes 2 & 3
   IRIX 6.5.2        yes                       Notes 2 & 3
   IRIX 6.5.3        yes                       Notes 2 & 3
   IRIX 6.5.4        yes                       Notes 2 & 3
   IRIX 6.5.5        yes                       Notes 2 & 3
   IRIX 6.5.6        yes                       Notes 2 & 3
   IRIX 6.5.7        yes                       Notes 2 & 3
   IRIX 6.5.8        yes                       Notes 2 & 3
   IRIX 6.5.9        yes                       Notes 2 & 3
   IRIX 6.5.10       yes                       Notes 2 & 3
   IRIX 6.5.11       no
   IRIX 6.5.12       no
   IRIX 6.5.13       no
   IRIX 6.5.14       no
   IRIX 6.5.15       no
   IRIX 6.5.16       no

   
   NOTES
 
     1) This version of the IRIX operating has been retired. Upgrade to an
        actively supported IRIX operating system.  See
        http://support.sgi.com/irix/news/index.html#policy for more
        information.

     2) If you have not received an IRIX 6.5.X CD for IRIX 6.5, contact your 
        SGI Support Provider or URL: http://support.sgi.com/irix/swupdates/

     3) Upgrade to IRIX 6.5.11 or a later version of IRIX.


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

SGI wishes to thank FIRST and the users of the Internet Community at
large for their assistance in this matter.


- -------------
- --- Links ---
- ------------- 

SGI Security Advisories can be found at:
http://www.sgi.com/support/security/ and
ftp://patches.sgi.com/support/free/security/advisories/

SGI Security Patches can be found at:
http://www.sgi.com/support/security/ and 
ftp://patches.sgi.com/support/free/security/patches/

SGI patches for IRIX can be found at the following patch servers:
http://support.sgi.com/irix/ and ftp://patches.sgi.com/

SGI freeware updates for IRIX can be found at:
http://freeware.sgi.com/

SGI fixes for SGI open sourced code can be found on:
http://oss.sgi.com/projects/

SGI patches and RPMs for Linux can be found at:
http://support.sgi.com/linux/ or 
http://oss.sgi.com/projects/sgilinux-combined/download/security-fixes/

SGI patches for Windows NT or 2000 can be found at:
http://support.sgi.com/nt/

IRIX 5.2-6.4 Recommended/Required Patch Sets can be found at:
http://support.sgi.com/irix/ and ftp://patches.sgi.com/support/patchset/

IRIX 6.5 Maintenance Release Streams can be found at:
http://support.sgi.com/colls/patches/tools/relstream/index.html

IRIX 6.5 Software Update CDs can be obtained from:
http://support.sgi.com/irix/swupdates/

The primary SGI anonymous FTP site for security advisories and patches is
patches.sgi.com (216.32.174.211).  Security advisories and patches are
located under the URL ftp://patches.sgi.com/support/free/security/

For security and patch management reasons, ftp.sgi.com (mirrors
patches.sgi.com security FTP repository) lags behind and does not do a
real-time update.


- -----------------------------------------
- --- SGI Security Information/Contacts ---
- -----------------------------------------

If there are questions about this document, email can be sent to
security-info@sgi.com.

                      ------oOo------

SGI 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 advisories and patches is
patches.sgi.com (216.32.174.211).  Security advisories and patches are
located under the URL ftp://patches.sgi.com/support/free/security/

The SGI 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 
security-info@sgi.com.

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

                      ------oOo------

SGI provides a free security mailing list service called wiretap and 
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subscribe wiretap <YourEmailAddress> 
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In the example above, <YourEmailAddress> is the email address that you wish
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                      ------oOo------

SGI provides a comprehensive customer World Wide Web site. This site is 
located at http://www.sgi.com/support/security/ .

                      ------oOo------

If there are general security questions on SGI systems, email can be sent to
security-info@sgi.com.

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, SGI is appropriately credited and the document retains and 
      includes its valid PGP signature.

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