document id		Synopsis		Date
57619		X Display Manager (xdm(1)) May Crash Due to Invalid XDMCP Request		9 Aug 2004

Description

Top

Sun(sm) Alert Notification

Sun Alert ID: 57619
Synopsis: X Display Manager (xdm(1)) May Crash Due to Invalid XDMCP Request
Category: Security
Product: Solaris
BugIDs: 5023755
Avoidance: Workaround, Patch
State: Engineering Complete
Date Released: 09-Aug-2004
Date Closed:
Date Modified:

1. Impact

A remote unprivileged user may be able to crash the X Display Manager (xdm(1)) when using an invalid X Display Manager Control Protocol (XDMCP) request, thus causing a Denial of Service (DoS).

2. Contributing Factors

This issue can occur in the following releases:

SPARC Platform

Solaris 7
Solaris 8
Solaris 9 without patch 112785-38

x86 Platform

Solaris 7
Solaris 8
Solaris 9 without patch 112786-27

3. Symptoms

If the described issue occurs, the X Display Manager will exit without warning.

Solution Summary

Top

4. Relief/Workaround

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 XDMCP remote session access to a machine is not required at all, but graphical login access via xdm(1M) for console devices is required, xdm(1M) can be configured to not listen for XDMCP connections by editing the "/usr/openwin/lib/X11/xdm/xdm-config" file and adding the following line:

    DisplayManager.requestPort: 0

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

5. Resolution

This issue is addressed in the following releases:

SPARC Platform

Solaris 9 with patch 112785-34 or later

x86 Platform

Solaris 9 with patch 112786-27 or later

A final resolution is pending completion.

This Sun Alert notification is being provided to you on an "AS IS" basis. This Sun Alert notification may contain information provided by third parties. The issues described in this Sun Alert notification may or may not impact your system(s). Sun makes no representations, warranties, or guarantees as to the information contained herein. ANY AND ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT, ARE HEREBY DISCLAIMED. BY ACCESSING THIS DOCUMENT YOU ACKNOWLEDGE THAT SUN SHALL IN NO EVENT BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES THAT ARISE OUT OF YOUR USE OR FAILURE TO USE THE INFORMATION CONTAINED HEREIN. This Sun Alert notification contains Sun proprietary and confidential information. It is being provided to you pursuant to the provisions of your agreement to purchase services from Sun, or, if you do not have such an agreement, the Sun.com Terms of Use. This Sun Alert notification may only be used for the purposes contemplated by these agreements.