CERT Advisory 048

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CERT Advisory

 · 4 years ago

  

 
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CA-92:13                       CERT Advisory 
                               June 4, 1992 
                          SunOS NIS Vulnerability 
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The Computer Emergency Response Team/Coordination Center (CERT/CC) has 
received information concerning several vulnerabilities with NIS under 
Sun Microsystems, Inc. SunOS.  These vulnerabilities exist in NIS under 
SunOS 4.1, 4.1.1, and 4.1.2, and may or may not exist in earlier versions 
of NIS. 

Sun has provided fixes for SunOS 4.1, 4.1.1, and 4.1.2 for these 
vulnerabilities.  The patch file containing these fixes is available 
through your local Sun Answer Center and through anonymous ftp from 
ftp.uu.net (137.39.1.9) in the /systems/sun/sun-dist directory.  Note 
that these fixes will probably not be compatible with SunOS 4.0.3 and 
earlier versions of the operating system. 

Fix                              PatchID      Filename            Checksum 
/usr/etc/{ypserv,ypxfrd,portmap} 100482-2     100482-02.tar.Z     53416   284 

Please note that Sun will occasionally update patch files.  If you 
find that the checksum is different, please contact Sun or the CERT/CC 
for verification. 

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I.   Description 

     A security vulnerability exists under NIS allowing unauthorized access 
     to NIS information. 

II.  Impact 

     A user on a remote host can obtain copies of the NIS maps from a 
     system running NIS.  The remote user can attempt to guess passwords 
     for the system using the obtained NIS password map information. 

III. Solution 

     A.  Obtain and install the patch from Sun or from ftp.uu.net following 
         the instructions provided in the "README" file.   

         1.  As root, rename the existing versions of 
             /usr/etc/{ypserv,ypxfrd,portmap} and modify the 
             permissions to prevent misuse. 

             # mv /usr/etc/ypserv /usr/etc/ypserv.orig 
             # mv /usr/etc/ypxfrd /usr/etc/ypxfrd.orig 
             # mv /usr/etc/portmap /usr/etc/portmap.orig 
             # chmod 0400 /usr/etc/ypserv.orig  
             # chmod 0400 /usr/etc/ypxfrd.orig 
             # chmod 0400 /usr/etc/portmap.orig 

         2.  Copy the new binaries into the /usr/etc directory. 

             # cp `arch`/{4.1, 4.1.1, 4.1.2}/ypserv /usr/etc/ypserv 
             # cp `arch`/{4.1, 4.1.1, 4.1.2}/ypxfrd /usr/etc/ypxfrd 
             # cp `arch`/{4.1, 4.1.1, 4.1.2}/portmap /usr/etc/portmap 
             # chown root /usr/etc/ypserv /usr/etc/ypxfrd /usr/etc/portmap 
             # chmod 755 /usr/etc/ypserv /usr/etc/ypxfrd /usr/etc/portmap 

         3.  Copy the securenets file to the /var/yp directory.  Any 
             site that has an existing /var/yp/securenets file should  
             rename it prior copying the new version of the file. 

             # cp `arch`/{4.1, 4.1.1, 4.1.2}/securenets /var/yp 
             # chown root /var/yp/securenets 
             # chmod 644 /var/yp/securenets 

         4.  Edit the /var/yp/securenets file to reflect the correct 
             configuration for your site.  See the "README" file for 
             details of the file syntax and special instructions for 
             hosts with multiple Ethernet interfaces.  The file should 
             not contain any blank lines. 
  
         5.  Reboot the system to invoke the new binaries. 

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The CERT/CC would like to thank Casper Dik of the University of Amsterdam, 
The Netherlands, and Peter Lamb of the Division of Information Technology, 
Commonwealth Scientific and Industrial Research Organization, Australia, 
for their assistance.  We also wish to thank Sun Microsystems, Inc. for 
their response to this vulnerability. 
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If you believe that your system has been compromised, contact CERT/CC or 
your representative in FIRST (Forum of Incident Response and Security Teams). 

Internet E-mail: cert@cert.org 
Telephone: 412-268-7090 (24-hour hotline) 
           CERT/CC personnel answer 7:30 a.m.-6:00 p.m. EST(GMT-5)/EDT(GMT-4), 
           on call for emergencies during other hours. 

Computer Emergency Response Team/Coordination Center (CERT/CC) 
Software Engineering Institute 
Carnegie Mellon University 
Pittsburgh, PA 15213-3890 

Past advisories, information about FIRST representatives, and other 
information related to computer security are available for anonymous ftp 
from cert.org (192.88.209.5). 

 
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