MDKSA-2002:025 - fix for insecure default kdm configuration

From: Mandrake Linux Security Team (security@linux-mandrake.com)
Date: Wed Mar 20 2002 - 19:47:13 PST

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    ________________________________________________________________________
    
                    Mandrake Linux Security Update Advisory
    ________________________________________________________________________
    
    Package name:           kdm
    Advisory ID:            MDKSA-2002:025
    Date:                   March 20th, 2002
    Affected versions:      7.1, 7.2, 8.0, Corporate Server 1.0.1
    ________________________________________________________________________
    
    Problem Description:
    
     A problem was discovered with the default configuration of the kdm
     display manager in Mandrake Linux.  By default, it allows XDMCP
     connections from any host, which can be used to obtain a login screen
     on your system remotely.  This can be used to get a list of users on
     that host, as displayed by kdm.  It can also be used to circumvent
     access control mechanisms such as tcpwrappers and root login
     restrictions on the console and via remote.
    
    Solution:
    
     To disable remote connections, edit the /etc/X11/xdm/Xaccess file and
     change the following two lines:
    
       *                         #any host can get a login window
       *  CHOOSER BROADCAST      #any indirect host can get a chooser
    
     to:
    
       #*                         #any host can get a login window
       #*  CHOOSER BROADCAST      #any indirect host can get a chooser
    
    
     Please note that Mandrake Linux 8.1 and 8.2 are not vulnerable to this
     as newer versions of kdm have a configuration option in the 
     /usr/share/config/kdm/kdmrc file which explicitly have XDMCP support
     disabled.
    
     Also please note that this is only valid if you are running kdm.
    ________________________________________________________________________
    
    References:
    
     http://www.procheckup.com/security_info/vuln_pr0208.html
     http://www.kb.cert.org/vuls/id/634847
    ________________________________________________________________________
    
    Updated Packages:
    
     There are no updated packages available.  Please refer to the Solution
     noted above for the fix.
    ________________________________________________________________________
    
    Bug IDs fixed (see https://qa.mandrakesoft.com for more information):
    
    ________________________________________________________________________
    
    To upgrade automatically, use MandrakeUpdate.  The verification of md5
    checksums and GPG signatures is performed automatically for you.
    
    If you want to upgrade manually, download the updated package from one 
    of our FTP server mirrors and upgrade with "rpm -Fvh *.rpm".  A list of
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      http://www.mandrakesecure.net/en/ftp.php
    
    Please verify the update prior to upgrading to ensure the integrity of
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      rpm --checksig <filename>
    
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    Please be aware that sometimes it takes the mirrors a few hours to 
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    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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