Mandrake alert: Updated gdm packages fix vulnerabilities

Posted by dave on Aug 21, 2003 4:10 PM EDT
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Several vulnerabilities were discovered in versions of gdm prior to 2.4.1.6. The first vulnerability is that any user can read any text file on the system due to code originally written to be run as the user logging in was in fact being run as the root user. This code is what allows the examination of the ~/.xsession-errors file. If a user makes a symlink from this file to any other file on the system during the session and ensures that the session lasts less than ten seconds, the user can read the file provided it was readable as a text file.

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________________________________________________________________________

                Mandrake Linux Security Update Advisory
________________________________________________________________________

Package name:           gdm
Advisory ID:            MDKSA-2003:085
Date:                   August 21st, 2003

Affected versions:	9.0, 9.1, Corporate Server 2.1
________________________________________________________________________

Problem Description:

 Several vulnerabilities were discovered in versions of gdm prior to
 2.4.1.6.  The first vulnerability is that any user can read any text
 file on the system due to code originally written to be run as the user
 logging in was in fact being run as the root user.  This code is what
 allows the examination of the ~/.xsession-errors file.  If a user makes
 a symlink from this file to any other file on the system during the
 session and ensures that the session lasts less than ten seconds, the
 user can read the file provided it was readable as a text file.
 
 Another two vulnerabilities were found in the XDMCP code that could be
 exploited to crash the main gdm daemon which would inhibit starting
 any new sessions (although the current session would be unaffected).
 The first problem here is due to the indirect query structure being
 used right after being freed due to a missing 'continue' statement in a
 loop; this happens if a choice of server expired and the client tried
 to connect.
 
 The second XDMCP problem is that when authorization data is being
 checked as a string, the length is not checked first.  If the data is
 less than 18 bytes long, the daemon may wander off the end of the
 string a few bytes in the strncmp which could cause a SEGV.
 
 These updated packages bring gdm to version 2.4.1.6 which is not
 vulnerable to any of these problems.  Also note that XDMCP support is
 disabled by default in gdm.
________________________________________________________________________

References:
  
  http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0547
  http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0548
  http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0549
________________________________________________________________________

Updated Packages:
  
 Corporate Server 2.1:
 47a2d84bfff0e842657e789e085b434d  corporate/2.1/RPMS/gdm-2.4.1.6-0.2mdk.i586.rpm
 8536d89374219e42ad6ca6c441ffb0d1  corporate/2.1/RPMS/gdm-Xnest-2.4.1.6-0.2mdk.i586.rpm
 35ab7f8231548f1daa4571bfb5e77054  corporate/2.1/SRPMS/gdm-2.4.1.6-0.2mdk.src.rpm

 Corporate Server 2.1/x86_64:
 252fc231c85e88411ca50a05f0404688  x86_64/corporate/2.1/RPMS/gdm-2.4.1.6-0.2mdk.x86_64.rpm
 3f8b47c14e0d7fc4c2d76171e3ee0b5a  x86_64/corporate/2.1/RPMS/gdm-Xnest-2.4.1.6-0.2mdk.x86_64.rpm
 35ab7f8231548f1daa4571bfb5e77054  x86_64/corporate/2.1/SRPMS/gdm-2.4.1.6-0.2mdk.src.rpm

 Mandrake Linux 9.0:
 47a2d84bfff0e842657e789e085b434d  9.0/RPMS/gdm-2.4.1.6-0.2mdk.i586.rpm
 8536d89374219e42ad6ca6c441ffb0d1  9.0/RPMS/gdm-Xnest-2.4.1.6-0.2mdk.i586.rpm
 35ab7f8231548f1daa4571bfb5e77054  9.0/SRPMS/gdm-2.4.1.6-0.2mdk.src.rpm

 Mandrake Linux 9.1:
 9d8a97cc5f475f16eeb73caa9d7d8e6b  9.1/RPMS/gdm-2.4.1.6-0.3mdk.i586.rpm
 4f866c5b5b4903d1b0751bcb6dc28d0f  9.1/RPMS/gdm-Xnest-2.4.1.6-0.3mdk.i586.rpm
 91f0ff2421135e32f604d6cb82081439  9.1/SRPMS/gdm-2.4.1.6-0.3mdk.src.rpm

 Mandrake Linux 9.1/PPC:
 0cb8fbd74766c4d0036cab36d57b6081  ppc/9.1/RPMS/gdm-2.4.1.6-0.3mdk.ppc.rpm
 fb0df358c4d6c9a7cf3982c4d3258004  ppc/9.1/RPMS/gdm-Xnest-2.4.1.6-0.3mdk.ppc.rpm
 91f0ff2421135e32f604d6cb82081439  ppc/9.1/SRPMS/gdm-2.4.1.6-0.3mdk.src.rpm
________________________________________________________________________

Bug IDs fixed (see https://qa.mandrakesoft.com for more information):
________________________________________________________________________

To upgrade automatically, use MandrakeUpdate or urpmi.  The verification
of md5 checksums and GPG signatures is performed automatically for you.

A list of FTP mirrors can be obtained from:

  http://www.mandrakesecure.net/en/ftp.php

All packages are signed by MandrakeSoft for security.  You can obtain
the GPG public key of the Mandrake Linux Security Team by executing:

  gpg --recv-keys --keyserver http://www.mandrakesecure.net 0x22458A98

Please be aware that sometimes it takes the mirrors a few hours to
update.

You can view other update advisories for Mandrake Linux at:

  http://www.mandrakesecure.net/en/advisories/

MandrakeSoft has several security-related mailing list services that
anyone can subscribe to.  Information on these lists can be obtained by
visiting:

  http://www.mandrakesecure.net/en/mlist.php

If you want to report vulnerabilities, please contact

  security_linux-mandrake.com

Type Bits/KeyID     Date       User ID
pub  1024D/22458A98 2000-07-10 Linux Mandrake Security Team
  <security linux-mandrake.com>
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