Mandrake alert: fix for insecure default kdm configuration

Posted by dave on Mar 20, 2002 6:44 PM EDT
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A problem was discovered with the default configuration of the kdm display manager in Mandrake Linux.

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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.


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


#* #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: ________________________________________________________________________

Updated Packages:

There are no updated packages available. Please refer to the Solution noted above for the fix. ________________________________________________________________________

Bug IDs fixed (see 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 FTP mirrors can be obtained from:

Please verify the update prior to upgrading to ensure the integrity of the downloaded package. You can do this with the command:

rpm --checksig <filename>

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

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

You can view other update advisories for Mandrake Linux at:

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

If you want to report vulnerabilities, please contact ________________________________________________________________________

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