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Category:   Application (Multimedia)  >   SGI O2 Workstation Vendors:   SGI (Silicon Graphics)
SGI IRIX O2 Video Workstation Allows Remote Users to View the Screen Display on the System
SecurityTracker Alert ID:  1003389
SecurityTracker URL:  http://securitytracker.com/id/1003389
CVE Reference:   GENERIC-MAP-NOMATCH   (Links to External Site)
Date:  Jan 29 2002
Impact:   Disclosure of authentication information, Disclosure of system information, Disclosure of user information, Root access via network, User access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  

Description:   SGI issued an advisory warning of a vulnerability in their SGI O2 video workstation. In a certain configuration, a remote user can view the screen display of the remote system.

It is reported that when the vcp Default Input is set to "Output Video", a remote user can log into the system, launch videoout and then videoin, and then view the display on the screen of the remote system. This can apparently be achieved regardless of the xhosts or xauth settings on the remote system. This could lead to a root level compromise of the system.

Impact:   A remote user can view the screen display of the remote system.
Solution:   SGI recommends the following steps to neutralize the exposure. You can work around the problem by adding the following to /var/X11/xdm/Xstartup:

#
# Set the permissions of /dev/mvp so only the console user has access
#
if [ -r /dev/mvp ]; then
chown $USER /dev/mvp
chmod 600 /dev/mvp
fi

Add the following to /var/X11/xdm/Xreset:

#
# Reset the permissions on /dev/mvp
#
if [ -r /dev/mvp ]; then
chown root /dev/mvp
chmod 666 /dev/mvp
fi

These modifications change the ownership of the mvp device when a user logs in and back out. When the device is owned by the user with 600 permissions, nobody else is able to execute vcp, videoin, or videoout. Thus nobody can see what's on the console of the system.

The /dev/mvp device only exists on O2s, so this problem does not impact other IRIX platforms (Octane, Onyx, etc.)

After these modifications have been made, it is also not possible to login remotely and access other video signals.

Vendor URL:  www.sgi.com/o2/ (Links to External Site)
Cause:   Access control error, Configuration error
Underlying OS:  UNIX (SGI/IRIX)

Message History:   None.


 Source Message Contents

Subject:  [VulnWatch] IRIX O2 video security issue


-----BEGIN PGP SIGNED MESSAGE-----

______________________________________________________________________________
                          SGI Security Advisory

        Title:   IRIX O2 video security issue
        Number:  20020103-01-I
        Date:    January 28, 2002
______________________________________________________________________________

SGI provides this information freely to the SGI user community for its
consideration, interpretation, implementation and use.   SGI recommends
that this information be acted upon as soon as possible.

SGI provides the information in this Security Advisory on an "AS-IS" basis
only, and disclaims all warranties with respect thereto, express, implied
or otherwise, including, without limitation, any warranty of merchantability
or fitness for a particular purpose.  In no event shall SGI be liable for
any loss of profits, loss of business, loss of data or for any indirect,
special, exemplary, incidental or consequential damages of any kind arising
from your use of, failure to use or improper use of any of the instructions
or information in this Security Advisory.
______________________________________________________________________________

- -----------------------
- --- Issue Specifics ---
- -----------------------

SGI has been informed of a security problem specific to video i/o on SGI O2
systems.  When the vcp Default Input is set to "Output Video", a remote user
can log into the system, launch videoout and then videoin and can then see
what is happening on the screen of the remote system (reading mail, etc...).
This can be done regardless of xhosts or xauth settings on the remote
system.

SGI has investigated the issues and recommends the following steps for
neutralizing the exposure.  It is HIGHLY RECOMMENDED that these measures be
implemented on ALL vulnerable SGI systems.


- --------------
- --- Impact ---
- --------------

This problem exists on all SGI O2 systems.

This vulnerability may be exploited by a local user, a local account is
required.

The exploitation of this vulnerabilitiy can lead to a root compromise.


- ------------------
- --- Workaround ---
- ------------------

There is as yet no patch that addresses this issue. You can work around
the problem by adding the following to /var/X11/xdm/Xstartup:

  #
  # Set the permissions of /dev/mvp so only the console user has access
  #
  if [ -r /dev/mvp ]; then
    chown $USER /dev/mvp
    chmod 600 /dev/mvp
  fi

Add the following to /var/X11/xdm/Xreset:

  #
  # Reset the permissions on /dev/mvp
  #
  if [ -r /dev/mvp ]; then
    chown root /dev/mvp
    chmod 666 /dev/mvp
  fi

These modifications change the ownership of the mvp device when a user logs
in and back out.  When the device is owned by the user with 600 permissions,
nobody else is able to execute vcp, videoin, or videoout.  Thus nobody can
see what's on the console of the system.

The /dev/mvp device only exists on O2s, so this problem does not impact
other IRIX platforms (Octane, Onyx, etc.)

After these modifications have been made, it is also not possible to login
remotely and access other video signals.


- ----------------
- --- Solution ---
- ----------------

SGI has not released a patch for this issue.  Please follow the workaround
instructions above.


- -------------------
- --- Information ---
- -------------------

SGI Security Advisories can be found at:
http://www.sgi.com/support/security/ and
ftp://patches.sgi.com/support/free/security/advisories/

SGI Security Patches can be found at:
http://www.sgi.com/support/security/ and
ftp://patches.sgi.com/support/free/security/patches/

SGI patches for IRIX can be found at the following patch servers:
http://support.sgi.com/irix/ and ftp://patches.sgi.com/

SGI freeware updates for IRIX can be found at:
http://freeware.sgi.com/

SGI fixes for SGI open sourced code can be found on:
http://oss.sgi.com/projects/

SGI patches and RPMs for Linux can be found at:
http://support.sgi.com/linux/ or
http://oss.sgi.com/projects/sgilinux-combined/download/security-fixes/

SGI patches for Windows NT or 2000 can be found at:
http://support.sgi.com/nt/

IRIX 5.2-6.4 Recommended/Required Patch Sets can be found at:
http://support.sgi.com/irix/ and ftp://patches.sgi.com/support/patchset/

IRIX 6.5 Maintenance Release Streams can be found at:
http://support.sgi.com/colls/patches/tools/relstream/index.html

IRIX 6.5 Software Update CDs can be obtained from:
http://support.sgi.com/irix/swupdates/

The primary SGI anonymous FTP site for security advisories and patches is
patches.sgi.com (216.32.174.211).  Security advisories and patches are
located under the URL ftp://patches.sgi.com/support/free/security/

For security and patch management reasons, ftp.sgi.com (mirrors
patches.sgi.com security FTP repository) lags behind and does not do a
real-time update.


- ------------------------
- --- Acknowledgments ----
- ------------------------

SGI wishes to thank the SGI customer who discovered this vulnerability and
the users of the Internet Community at large for their assistance in this
matter.


- -----------------------------------------
- --- SGI Security Information/Contacts ---
- -----------------------------------------

If there are questions about this document, email can be sent to
security-info@sgi.com.

                      ------oOo------

SGI provides security information and patches for use by the entire SGI
community.  This information is freely available to any person needing the
information and is available via anonymous FTP and the Web.

The primary SGI anonymous FTP site for security advisories and patches is
patches.sgi.com (216.32.174.211).  Security advisories and patches are
located under the URL ftp://patches.sgi.com/support/free/security/

The SGI Security Headquarters Web page is accessible at the URL:
http://www.sgi.com/support/security/

For issues with the patches on the FTP sites, email can be sent to
security-info@sgi.com.

For assistance obtaining or working with security patches, please
contact your SGI support provider.

                      ------oOo------

SGI provides a free security mailing list service called wiretap and
encourages interested parties to self-subscribe to receive (via email) all
SGI Security Advisories when they are released. Subscribing to the mailing
list can be done via the Web
(http://www.sgi.com/support/security/wiretap.html) or by sending email to
SGI as outlined below.

% mail wiretap-request@sgi.com
subscribe wiretap <YourEmailAddress>
end
^d

In the example above, <YourEmailAddress> is the email address that you wish
the mailing list information sent to.  The word end must be on a separate
line to indicate the end of the body of the message. The control-d (^d) is
used to indicate to the mail program that you are finished composing the
mail message.


                      ------oOo------

SGI provides a comprehensive customer World Wide Web site. This site is
located at http://www.sgi.com/support/security/ .

                      ------oOo------

If there are general security questions on SGI systems, email can be sent to
security-info@sgi.com.

For reporting *NEW* SGI security issues, email can be sent to
security-alert@sgi.com or contact your SGI support provider.  A support
contract is not required for submitting a security report.

______________________________________________________________________________
      This information is provided freely to all interested parties
      and may be redistributed provided that it is not altered in any
      way, SGI is appropriately credited and the document retains and
      includes its valid PGP signature.

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