__________________________________________________________

                       The U.S. Department of Energy
                   Computer Incident Advisory Capability
                           ___  __ __    _     ___
                          /       |     /_\   /
                          \___  __|__  /   \  \___
             __________________________________________________________

                             INFORMATION BULLETIN

Sun Linux Vulnerability in VNC Package may allow local or remote unauthorized access
                             [Sun Alert ID: 56161]

September 2, 2003 18:00 GMT                                       Number N-140
______________________________________________________________________________
PROBLEM:       A vulnerability with the VNC DES authentication scheme 
               implementation may allow a local or remote unpriviledged user 
               to gain unauthorized access to the system. 
PLATFORM:      Sun Linux 5.0 
DAMAGE:        The intruder can gain access to the cookie and gain access to 
               the system. 
SOLUTION:      Apply patches as stated in Sun's Security Notification. 
______________________________________________________________________________
VULNERABILITY  The risk is MEDIUM. An unauthorized user could break into the 
ASSESSMENT:    encrypted channel and take over the system. 
______________________________________________________________________________
LINKS: 
 CIAC BULLETIN:      http://www.ciac.org/ciac/bulletins/n-140.shtml 
 ORIGINAL BULLETIN:                                                           
                     http://www.sunsolve.sun.com/pub-cgi/retrieve.pl?doc=
                     fsalert%2F56161&zone_32=category%3Asecurity 
______________________________________________________________________________
[***** Start Sun Alert ID: 56161 *****]

Sun(sm) Alert Notification 
Sun Alert ID: 56161 
Synopsis: Sun Linux Vulnerability in VNC Package May Allow Local or Remote 
          Unauthorized Access 
Category: Security 
Product: Sun Linux 
BugIDs: 4892275 
Avoidance: Workaround 
State: Committed 
Date Released: 19-Aug-2003 
Date Closed: 
Date Modified: 

1. Impact 
A vulnerability with the VNC DES authentication scheme implementation may 
allow a local or remote unprivileged user to gain unauthorized access to the 
system. The script for starting the VNC server generates a cookie (which is 
used for X authentication) without using a sufficiently strong random number 
generator. 

Note: VNC is a tool for providing a remote graphical user interface. 

More information on this issue is available at: 

Red Hat Advisory RHSA-2003:041-15 at: https://rhn.redhat.com/errata/
                                              RHSA-2003-041.html 
CVE CAN-2002-1511 at: http://cve.mitre.org/cgi-bin/cvename.cgi?name=
                             CAN-2002-1511 
CVE CAN-2002-1336 at: http://cve.mitre.org/cgi-bin/cvename.cgi?name=
                             CAN-2002-1336 
							 
2. Contributing Factors 
This issue can occur in the following releases: 

Sun Linux 

Sun Linux 5.0 (LX50) with VNC versions 3.3.3r2-18.4 or earlier 
Notes: Sun Linux 5.0 is currently shipped with the Sun LX50 Server. 

The VNC package version can be determined by running the following command: 

    $ rpm -qa | grep -i vnc
    vnc-3.3.3r2-18.4      
	                                                     
3. Symptoms 
There are no predictable symptoms that would indicate the described issue has 
been exploited. 

Solution Summary Top 

4. Relief/Workaround 
To work around the described issue until patches can be applied, temporarily 
disable VNC with the following steps: 

1. To see if VNC is enabled (displayed at all run levels), use the following 
command: 

    # /sbin/chkconfig --list vncserver
    vncserver       0:off   1:off   2:off   3:on   4:on   5:on   6:off     
	                  
2. Disable VNC for all run levels with the following command: 

    # /sbin/chkconfig --del vncserver                                                     
5. Resolution 
Sun Linux patches will be available at: http://sunsolve.sun.com/patches/
                                               linux/security.html 

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. 

Copyright 2000-2003 Sun Microsystems, Inc., 4150 Network Circle, 
Santa Clara, CA 95054 U.S.A. All rights reserved.

[***** End Sun Alert ID: 56161 *****]
_______________________________________________________________________________

CIAC wishes to acknowledge the contributions of Sun Microsystems for the 
information contained in this bulletin.
_______________________________________________________________________________


CIAC, the Computer Incident Advisory Capability, is the computer
security incident response team for the U.S. Department of Energy
(DOE) and the emergency backup response team for the National
Institutes of Health (NIH). CIAC is located at the Lawrence Livermore
National Laboratory in Livermore, California. CIAC is also a founding
member of FIRST, the Forum of Incident Response and Security Teams, a
global organization established to foster cooperation and coordination
among computer security teams worldwide.

CIAC services are available to DOE, DOE contractors, and the NIH. CIAC
can be contacted at:
    Voice:    +1 925-422-8193 (7x24)
    FAX:      +1 925-423-8002
    STU-III:  +1 925-423-2604
    E-mail:   ciac@ciac.org

Previous CIAC notices, anti-virus software, and other information are
available from the CIAC Computer Security Archive.

   World Wide Web:      http://www.ciac.org/
   Anonymous FTP:       ftp.ciac.org

PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
communities receive CIAC bulletins.  If you are not part of these
communities, please contact your agency's response team to report
incidents. Your agency's team will coordinate with CIAC. The Forum of
Incident Response and Security Teams (FIRST) is a world-wide
organization. A list of FIRST member organizations and their
constituencies can be obtained via WWW at http://www.first.org/.

This document was prepared as an account of work sponsored by an
agency of the United States Government. Neither the United States
Government nor the University of California nor any of their
employees, makes any warranty, express or implied, or assumes any
legal liability or responsibility for the accuracy, completeness, or
usefulness of any information, apparatus, product, or process
disclosed, or represents that its use would not infringe privately
owned rights. Reference herein to any specific commercial products,
process, or service by trade name, trademark, manufacturer, or
otherwise, does not necessarily constitute or imply its endorsement,
recommendation or favoring by the United States Government or the
University of California. The views and opinions of authors expressed
herein do not necessarily state or reflect those of the United States
Government or the University of California, and shall not be used for
advertising or product endorsement purposes.

LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC)

N-130: SGI IRIX nsd Server AUTH_UNIX gid list Vulnerability
N-131: Sun Solaris Runtime Linker ld.so.1(1) Vulnerability
N-132: Red Hat  wu-ftpd Buffer Overflow Vulnerability
N-133: Blaster Worm (aka: W32.Blaster, MSBlast, Lovsan, Win32.Poza)
N-134: Sun cachefs Patches May Overwrite inetd.conf File
N-135: Microsoft Cumulative Patch for Internet Explorer 
N-136: Microsoft Unchecked Buffer in MDAC Function Vulnerability 
N-137: Red Hat Updated pam_smb packages fix remote buffer overflow
N-138: Red Hat Updated Sendmail packages fix vulnerability
N-139: Red Hat Updated SSL Certificate for access to 'up2date'