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__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Capability
___ __ __ _ ___
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__________________________________________________________
INFORMATION BULLETIN
Vulnerability in xlock
November 6, 1997 17:00 GMT Number H-54a
______________________________________________________________________________
PROBLEM: A buffer overflow condition exists in some implementations of
xlock.
PLATFORM: See "Appendix A - Vendor Information" below for platforms
effected.
DAMAGE: Local users may gain root privileges.
SOLUTION: If your system is vulnerable, install vendor patches or apply
the workaround described in Section III.B.
______________________________________________________________________________
VULNERABILITY Exploit details involving this vulnerability have been made
ASSESSMENT: publicly available.
[ Appended to H-54 on November 6, 1997 with patch release information from
Hewlett-Packard ]
[ Start CERT Advisory ]
=============================================================================
CERT* Advisory CA-97.13
Original issue date: May 7, 1997
Last revised: --
Topic: Vulnerability in xlock
- ------------------------------------------------------------------------------
The CERT Coordination Center has received reports that a buffer overflow
condition exists in some implementations of xlock. This vulnerability makes it
possible for local users (users with access to an account on the system) to
execute arbitrary programs as a privileged user.
Exploitation information involving this vulnerability has been made publicly
available.
If your system is vulnerable, the CERT/CC team recommends installing a
patch from your vendor. If you are not certain whether your system is
vulnerable or if you know that your system is vulnerable and you cannot add a
patch immediately, we urge you to apply the workaround described in
Section III.B.
We will update this advisory as we receive additional information.
Please check our advisory files regularly for updates that relate to your
site.
- ------------------------------------------------------------------------------
I. Description
xlock is a program that allows a user to "lock" an X terminal. A buffer
overflow condition exists in some implementations of xlock. It is
possible attain unauthorized access to a system by engineering a
particular environment and calling a vulnerable version of xlock that has
setuid or setgid bits set. Information about vulnerable versions must be
obtained from vendors. Some vendor information can be found in Appendix A
of this advisory.
Exploitation information involving this vulnerability has been made
publicly available.
Note that this problem is different from that discussed in CERT Advisory
CA-97.11.libXt.
II. Impact
Local users are able to execute arbitrary programs as a privileged user
without authorization.
III. Solution
Install a patch from your vendor as described in Solution A. If you are
not certain whether your system is vulnerable or if you know that your
system is vulnerable and you cannot install a patch immediately, we
recommend Solution B.
A. Obtain and install a patch for this problem.
Below is a list of vendors who have provided information about
xlock. Details are in Appendix A of this advisory; we will
update the appendix as we receive more information. If your
vendor's name is not on this list, the CERT/CC did not hear from
that vendor. Please contact your vendor directly.
Berkeley Software Design, Inc. (BSDI)
Cray Research - A Silicon Graphics Company
Data General Corporation
Digital Equipment Corporation
FreeBSD, Inc.
Hewlett-Packard Company
IBM Corporation
LINUX
NEC Corporation
The Open Group [This group distributes the publicly available
software
that was formerly distributed by X Consortium]
Solbourne
Sun Microsystems, Inc.
B. We recommend the following workaround if you are not certain
whether your system is vulnerable or if you know that your system
is vulnerable and you cannot install a patch immediately.
1. Find and disable any copies of xlock that exist on your system and
that have the setuid or setgid bits set.
2. Install a version of xlock known to be immune to this
vulnerablility. One such supported tool is xlockmore. The latest
version of this tool is 4.02, and you should ensure that this is
the version you are using. This utility can be obtained from the
following site:
ftp://ftp.x.org/contrib/applications/xlockmore-4.02.tar.gz
MD5 (xlockmore-4.02.tar.gz) = c158e6b4b99b3cff4b52b39219dbfe0e
You can also obtain this version from mirror sites. A list of
these sites will be displayed if you are not able to access the
above archive due to load.
_________________________________________________________________________
Appendix A - Vendor Information
Below is a list of the vendors who have provided information for this
advisory. We will update this appendix as we receive additional information.
If you do not see your vendor's name, the CERT/CC did not hear from that
vendor. Please contact the vendor directly.
Berkeley Software Design, Inc. (BSDI)
=====================================
BSD/OS is not vulnerable to the problem in xlock since our
xlock is not setuid.
Cray Research - A Silicon Graphics Company
==========================================
Cray Research does not include xlock in its X Window releases, so we are
not at risk on the xlock buffer overflow problem.
Data General Corporation
========================
The xlock sources (xlockmore-3.7) that DG includes in its contributed
software package have been modified to remove this vulnerability. These
will be available when release 8 comes out. We also recommend that our
customers who have the current version should change the sprintf calls in
resource.c to snprintf calls, rebuild and reinstall the package.
Digital Equipment Corporation
=============================
This reported problem is not present for Digital's ULTRIX or
Digital UNIX Operating Systems Software.
FreeBSD, Inc.
=============
The xlockmore version we ship in our ports collection is vulnerable
in all shipped releases. The port in FreeBSD-current is fixed.
Solution is to install the latest xlockmore version (4.02).
Hewlett-Packard Company
=======================
We ship an suid root program vuelock that is based on xlock.
It does have the vulnerability.
The only workaround is to remove the executable, the patch is "in process".
IBM Corporation
===============
AIX is vulnerable to the conditions described in this advisory.
The following APARs will be released soon:
AIX 3.2: APAR IX68189
AIX 4.1: APAR IX68190
AIX 4.2: APAR IX68191
IBM and AIX are registered trademarks of International Business Machines
Corporation.
LINUX
=====
Red Hat:
Not vulnerable
Caldera:
Not vulnerable
Debian:
An updated package is on the Debian site
SuSE:
ftp://ftp.suse.com/pub/SuSE-Linux/suse_update/S.u.S.E.-
4.4.1/xap1/xlock
And in general the new Xlockmore release fixes the problems.
NEC Corporation
===============
UX/4800 Not vulnerable for all versions.
EWS-UX/V(Rel4.2MP) Not vulnerable for all versions.
EWS-UX/V(Rel4.2) Not vulnerable for all versions.
UP-UX/V(Rel4.2MP) Not vulnerable for all versions.
The Open Group
==============
Publicly available software that was formerly distributed by the X Consortium
- -
Not vulnerable.
Solbourne
=========
Solbourne is not vulnerable to this attack.
Sun Microsystems, Inc.
======================
We are producing patches for OpenWindows 3.0 for Sun OS versions
4.1.3_U1, 4.1.4, 5.3, 5.4, 5.5, and 5.5.1.
[ End CERT Advisory ]
[ Start Hewlett-Packard Advisory ]
Document ID: HPSBUX9711-073
Date Loaded: 971105
Title: Security Vulnerability in xlock on VVOS, HP-UX 10.24
- -------------------------------------------------------------------------
HEWLETT-PACKARD SECURITY BULLETIN: #00073, 4 November 1997
- -------------------------------------------------------------------------
The information in the following Security Bulletin should be acted upon
as soon as possible. Hewlett-Packard will not be liable for any
consequences to any customer resulting from customer's failure to fully
implement instructions in this Security Bulletin as soon as possible.
- -------------------------------------------------------------------------
PROBLEM: Vulnerabilities exist in xlock on VirtualVault 2.0/3.0 if patch
PHSS_9905 is installed.
PLATFORM: HP9000 Series 700/800s running:
HP-UX 10.24 (VVOS) with VirtualVault A.02.00 with patch PHSS_9905.
HP-UX 10.24 (VVOS) with VirtualVault A.03.00 with Extensions
Software (this includes PHSS_9905)
DAMAGE: The xlock vulnerability could result in allowing a local user
to gain unauthorized access to the system.
SOLUTION: Apply PHSS_12961 to correct the vulnerability.
AVAILABILITY: The patch is available now.
____________________________________________________________________
I.
A. Background
The xlock program allows a user to "lock" an X terminal while
maintaining their login session. A vulnerability exists in xlock
that could allow a local user to attain unauthorized access to the
system.
B. Fixing the problem
This problem can be eliminated by applying the recommended patch.
C. Recommended solution
Hewlett-Packard recommends that the PHSS_12961 patch be applied if
PHSS_9905 has already been installed. The PHSS_9905 patch is
included in the Software Extension Media provided with VirtualVault
A.03.00.
NOTE:
These problems only apply to systems running the VirtualVault
Operating System 10.24 that is part of the VirtualVault product
A.02.00 and A.03.00.
D. Impact of the patch
Applying PHSS_12961 eliminates the vulnerability in the xlock
program but does not otherwise impact the system.
E. To subscribe to automatically receive future NEW HP Security
Bulletins from the HP Electronic Support Center via electronic mail,
do the following:
Use your browser to get to the HP Electronic Support Center page at:
http://us-support.external.hp.com
(for US, Canada, Asia-Pacific, & Latin-America)
http://europe-support.external.hp.com
(for Europe)
Click on the Technical Knowledge Database, register as a user
(remember to save the User ID assigned to you, and your password),
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Near the bottom is a hyperlink to our Security Bulletin archive.
Once in the archive there is another link to our current
security patch matrix. Updated daily, this matrix is categorized
by platform/OS release, and by bulletin topic.
F. To report new security vulnerabilities, send email to
security-alert@hp.com
Please encrypt any exploit information using the security-alert
PGP key, available from your local key server, or by sending a
message with a -subject- (not body) of 'get key' (no quotes) to
security-alert@hp.com.
Permission is granted for copying and circulating this Bulletin to
Hewlett-Packard (HP) customers (or the Internet community) for the
purpose of alerting them to problems, if and only if, the Bulletin is
not edited or changed in any way, is attributed to HP, and provided
such reproduction and/or distribution is performed for non-commercial
purposes.
Any other use of this information is prohibited. HP is not liable
for any misuse of this information by any third party.
________________________________________________________________________
- -----End of Document ID: HPSBUX9711-073--------------------------------------
[ End Hewlett-Packard Advisory ]
______________________________________________________________________________
CIAC wishes to acknowledge the contributions of CERT, David Hedley, Kaleb
Keithley and Hewlett-Packard for the information contained in this bulletin.
______________________________________________________________________________
CIAC, the Computer Incident Advisory Capability, is the computer
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