Security Vulnerability Involving the Common Desktop Environment (CDE) dtlogin(1X) Command When Parsing XDMCP Requests (CERT VU#179804)

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Impact

A local or remote unprivileged user may be able to gain unauthorized root privileges or cause a denial of service due to a "double-free" vulnerability in the CDE login service dtlogin(1X) which can be triggered when parsing invalid X Display Manager Control Protocol (XDMCP) packets. If the dtlogin(1X) program is killed, users will be unable to login on any Sun Ray devices attached to the server, and the console will display the command line login prompt.

This issue is also described in CERT Vulnerability VU #179804 (see http://www.kb.cert.org/vuls/id/179804)

Contributing Factors

This issue can occur in the following releases:

SPARC Platform

• Solaris 7 without patch 107180-31
• Solaris 8 without patch 108919-21
• Solaris 9 without patch 112807-09

x86 Platform

• Solaris 7 wthout patch 107181-31
• Solaris 8 without patch 108920-21
• Solaris 9 without patch 114210-08

This issue may occur on systems running dtlogin(1X). To determine if dtlogin(1X) is running on a system, use the "ps" command as shown below:

    % ps -ef | grep dtlogin

Symptoms

If an application core file is captured for this issue, it will be found in "/core" and will contain a stack trace similar to the following:

    core 'core' of 2999:	/usr/dt/bin/dtlogin -daemon
    ff310dd8 XdmcpDisposeARRAY8 (0, 0, fef66fc0, fef6a680, ff080fe4, 0) + 4
    ff310e74 XdmcpDisposeARRAYofARRAY8 (ffbffb70, 0, 0, 0, ffbffc44, ff) + 1c
    00025528 request_respond (ffbffc44, 20, 6, ffbffbfc, 6, 0) + 464
    00024398 ProcessRequestSocket (6, 43c00, 1ac, ffbffc44, 270, 18) + 244
    00023f68 WaitForSomething (40, 20, 3f400, 6, 3ec00, 1) + 208
    000190e8 main     (2, 0, 48618, 48400, ffbffe7c, 48400) + 338
    00015b68 _start   (0, 0, 0, 0, 0, 0) + 10

Workaround

If dtlogin(1X) exits unexpectedly, it may be restarted using the following command as root:

    # /etc/init.d/dtlogin start

To reduce the possibility of the described issue from occurring, network administrators should block UDP(7P) packets to port 177 across any firewall where XDMCP remote session service is not required.

If no graphical login access is required for local console users, Sun Ray devices, or remote XDMCP sessions, dtlogin(1X) may be disabled completely by running the following command as root:

    # /usr/dt/bin/dtconfig -d

and then stop the currently running dtlogin:

    # /usr/dt/bin/dtconfig -kill

If XDMCP remote session access to a machine is not required at all, but graphical login access for the console and/or Sun Ray devices is required, dtlogin(1X) can be configured to not listen for XDMCP connections by editing the "/etc/dt/config/Xconfig file" and removing the "#" symbol at the beginning of the following line:

    #  Dtlogin.requestPort    0

If the "/etc/dt/config/Xconfig" file does not exist, create it by doing the following:

    # mkdir -p /etc/dt/config
    # cp /usr/dt/config/Xconfig /etc/dt/config
    # /etc/init.d/dtlogin reset

Note: Controlling access via the access control list in the "Xaccess" file is not effective at preventing this issue.

Resolution

This issue is addressed in the following releases:

SPARC Platform

• Solaris 7 with patch 107180-31 or later
• Solaris 8 with patch 108919-21 or later
• Solaris 9 with patch 112807-09 or later

x86 Platform

• Solaris 7 with patch 107181-31 or later
• Solaris 8 with patch 108920-21 or later
• Solaris 9 with patch 114210-08 or later

Modification History


Date: 10-MAY-2004

• Updated Contributing Factors and Resolution sections

Date: 11-JUN-2004

• Updated Relief/Workaround section

Date: 03-AUG-2004

• State: Resolved
• Updated Contributing Factors and Resolution sections

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