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Security Bulletin 9712 DISA Defense Communications System
June 2, 1997 Published by: DISN Security Coordination Center
(SCC@NIC.MIL) 1-(800) 365-3642
The DISN SECURITY BULLETIN is distributed by the DISN SCC (Security Coordination Center) under DISA contract as a means of communicating information on network and host security exposures, fixes, and concerns to security and management personnel at DISN facilities. Back issues may be obtained via FTP from NIC.MIL [207.132.116.5] using login= "anonymous" and password="guest". The bulletin pathname is scc/sec-yynn (where "yy" is the year the bulletin is issued and "nn" is a bulletin number, e.g. scc/sec-9705.txt). These are also available at our WWW site, http://nic.mil.
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! The following important advisory was issued by the Automated !
! Systems Security Incident Support Team (ASSIST) and is being !
! relayed unedited via the Defense Information Systems Agency's !
! Security Coordination Center distribution system as a means !
! of providing DISN subscribers with useful security information. !
! !
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/\ / \ / \ | / \ | | / Integritas
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/____\ \ \ | \ | | \ Celeritas
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Advisory: 97-04
Release date: 28 May 97
DESCRIPTION: Vulnerability in Xlock
PLATFORM: See list of affected systems below
IMPACT: A local user can execute commands as a privileged user
RECOMMENDED SOLUTIONS: If your system is vulnerable, install vendor patches
or apply the workaround described in Section III.B
[ Beginning of CERT Bulletin ]
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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.
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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.
Local users are able to execute arbitrary programs
as a privileged user without authorization.
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.
that was formerly distributed by X Consortium] Solbourne
Sun Microsystems, Inc.
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.
...........................................................................
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)
=====================================
Cray Research does not include xlock in its X Window
releases, so we are not at risk on the xlock buffer overflow problem.
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.
This reported problem is not present for Digital's
ULTRIX or Digital UNIX Operating Systems Software.
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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).
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".
AIX is vulnerable to the conditions described in this advisory.
The following APARs will be released soon:
IBM and AIX are registered trademarks of International
Business Machines Corporation.
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.
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.
Not vulnerable.
Solbourne is not vulnerable to this attack.
======================
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 of CERT Bulletin ]
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The ASSIST staff would like to thank the CERT Coordination Center for this bulletin as well as David Hedley for reporting the original problem and Kaleb Keithley at The Open Group for his support in the development of this advisory.
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ASSIST is an element of the Defense Information Systems Agency (DISA), Global Operations and Security Center (GOSC), which provides service to the entire DoD community. Constituents of the DoD with questions about ASSIST or computer security issues, can contact ASSIST using one of the methods listed below. Non-DoD organizations/institutions, contact the Forum of Incident Response and Security Teams (FIRST) representative. To obtain a list of FIRST member organizations and their constituencies send an email to docserver@first.org with an empty "subject" line and a message body containing the line "send first-contacts".
___________________________
ASSIST Bulletins, tools and other security related information are available from:
To be added to our mailing list for ASSIST bulletins, send your e-mail address to:
assist-request@assist.mil In the subject line, type:
___________________________________
OTHER DOD CERT CONTACT INFORMATION:
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Back issues of ASSIST bulletins, and other security related information, are available from the ASSIST BBS at 703-607-4710, 327-4710, and through anonymous FTP from ftp.assist.mil (IP address 199.211.123.12). Note: ftp.assist.mil will only accept anonymous FTP connections from Milnet addresses that are registered with the NIC or DNS. If your system is not registered, you must provide your MILNET IP address to ASSIST before access can be provided.
license, PGP may be used for non-commercial purposes only. Instructions for downloading the PGP software can also be obtained from net-dist.mit.edu in the pub/PGP/README file. PGP and RSAREF may be subject to the export control laws of the United States of America as implemented by the United States Department of State Office of Defense Trade Controls. The PGP signature information will be attached to the end of ASSIST bulletins.
Reference herein to any specific commercial product, process, or service by trade name, trademark manufacturer, or otherwise, does not constitute or imply its endorsement, recommendation, or favoring by ASSIST. The views and opinions of authors expressed herein shall not be used for advertising or product endorsement purposes.
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PLEASE NOTE: Some users outside of the DOD computing communities may receive DISN Security Bulletins. If you are not part of the DOD community, please contact your agency's incident response team to report incidents. Your agency's team will coordinate with DOD. 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 by sending email to docserver@first.org with an empty subject line and a message body containing the line: send first-contacts.
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