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Sun Solaris X Display Manager does not properly handle invalid XDMCP requests

Vulnerability Note VU#139504

Original Release Date: 2004-08-11 | Last Revised: 2004-08-11

Overview

There is a vulnerability in the way Sun Solaris handles invalid X Display Manager Control Protocol (XDMCP) requests. Exploitation of this vulnerability could allow an attacker to cause the X Display Manager (XDM) to crash.

Description

The X Display Manager (xdm(1)) is responsible for managing collections of X displays from local or remote servers using the X Display Manager Control Protocol (XDMCP). The Sun Solaris X Display Manager contains a denial-of-service vulnerability that could be triggered by an invalid XDMCP packet.

Impact

A remote attacker with the ability to send XDMCP packets to a vulnerable system could cause the X Display Manager to crash.

Solution

Apply patch

Sun has issued an advisory which addresses this issue. For more information on patches available for your system, please refer to Sun Security Alert 57619.


Restrict access

Block or restrict UDP(7P) packets destined for port 177/udp from untrusted networks such as the Internet.

Disable XDMCP connections

According to the Sun Security Alert, 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.

Vendor Information

139504
 
Affected   Unknown   Unaffected

Sun Microsystems Inc.

Updated:  August 11, 2004

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

Please refer to Sun Security Alert 57619.

If you have feedback, comments, or additional information about this vulnerability, please send us email.


CVSS Metrics

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A

References

Credit

This vulnerability was reported by Sun Microsystems.

This document was written by Damon Morda.

Other Information

CVE IDs: None
Severity Metric: 4.30
Date Public: 2004-08-09
Date First Published: 2004-08-11
Date Last Updated: 2004-08-11 18:39 UTC
Document Revision: 14

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