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__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Capability
___ __ __ _ ___
/ | /_\ /
\___ __|__ / \ \___
__________________________________________________________
INFORMATION BULLETIN
UNIX Buffer Overflow in rdist Vulnerability
November 20, 1998 17:00 GMT Number H-107
______________________________________________________________________________
PROBLEM: A new vulnerability has been found in some set-user-id root
implementations of rdist.
PLATFORM: UNIX operating systems - vendors are listed below in Section
III.
DAMAGE: This vulnerability may allow local users to gain root
privileges.
SOLUTION: Apply a vendor patch or a freely available version of rdist
that does not need to be installed as set-user-id root.
VULNERABILITY Exploit information involving these vulnerabilities have been
ASSESSMENT: made publicly available.
______________________________________________________________________________
[ Updated November 20, 1998 with additional patch information from Sun
Microsystems, Inc. ]
[ Start CERT Advisory ]
=============================================================================
CERT* Advisory CA-97.23
Original issue date: September 16, 1997
Last revised: --
Topic: Buffer Overflow Problem in rdist
- ------------------------------------------------------------------------------
The CERT Coordination Center has received reports of a vulnerability in rdist
that enables anyone with access to a local account to gain root privileges.
This is not the same vulnerability as the one discussed in CA-96.14.
Section III.A contains instructions on how to determine if your site is
vulnerable. If your implementation of rdist is vulnerable, the CERT/CC team
encourages you to follow your vendor's instructions (Sec. III.B and Appendix
A) or install a freely available version of the rdist program that is not
installed as set-user-id root and is, therefore, not susceptible to the
exploitation described in this advisory (Sec. III.C).
For information on the earlier problem with rdist, see
ftp://info.cert.org/pub/cert_advisories/CA-96.14.rdist_vul
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
The rdist program is a UNIX Operating System utility used to
distribute files from one host to another. On some systems, rdist
opens network connections using a privileged port as the source port.
This requires root privileges, and to attain these privileges rdist on
such systems is installed set-user-id root.
A new vulnerability has been found in some set-user-id root
implementations of rdist. The vulnerability lies in the function
expstr(), where macros supplied as arguments are expanded using
sprintf(). It is possible to overwrite stack frames and call specially
pre-crafted native machine code. If the appropriate machine code is
supplied, an attacker can execute arbitrary programs (such as the
shell) with set-user-id root privileges.
Note that this vulnerability is distinct from that discussed in CERT
advisory CA-96.14.
II. Impact
On systems with a vulnerable copy of rdist, anyone with access to a
local account can gain root access.
III. Solution
We urge you to follow the steps in Section A to determine if your
system is vulnerable and, if it is, to turn off rdist while you decide
how to proceed.
If your system is vulnerable and you need the functionality that rdist
provides, you should install a vendor patch (Section B). Until you can
do so, you may want to use a freely available version of rdist that
does not need to be installed as set-user-id root and is, therefore,
not susceptible to the exploitation described in this advisory
(Section C).
A. How to check for set-user-id root versions of rdist
To find set-user-id root versions of rdist and to disable the
programs that are possibly vulnerable, use the following find
command or a variant. Consult your local system documentation to
determine how to tailor the find program on your system.
You will need to run the find command on each system you maintain
because the command examines files on the local disk only.
Substitute the names of your local file systems for
FILE_SYSTEM_NAMES in the example. Example local file system names
are /, /usr, and /var. You must do this as root.
Note that this is one long command, though we have separated
it onto three lines using backslashes.
find FILE_SYSTEM_NAMES -xdev -type f -user root \
-name '*rdist*' -perm -04000 -exec ls -l '{}' \; \
-ok chmod 0500 '{}' \;
This command will find all files on a system that
- are only in the file system you name (FILE_SYSTEM_NAMES -xdev)
- are regular files (-type f)
- are owned by root (-user root)
- have "rdist" as a component of the name (-name '*rdist*')
- are setuid (-perm -04000)
Once found, those files will
- have their names and details printed (-exec ls -l '{}')
- have the setuid mode removed (making the file available
only to root) but only if you type `y' in response to the
prompt (-ok chmod 0500 '{}' \;)
B. Obtain and install the appropriate patch
Below is a list of vendors who have provided information for this
advisory. Details are in Appendix A, and we will update the appendix
as we receive more information.
Berkeley Software Design, Inc. (BSDI)
Digital Equipment Corp.
FreeBSD, Inc.
Hewlett-Packard Company
IBM Corporation
NEC Corporation
The Santa Cruz Operation, Inc. (SCO)
Siemens-Nixdorf
Silicon Graphics Inc. (SGI)
Sun Microsystems, Inc.
If your vendor's name is not on this list, please contact the
vendor directly.
C. If you need the functionality that rdist provides but a patched
version is not yet available from your vendor, consider installing
rdist-6.1.3, which is freely available from
ftp://usc.edu/pub/rdist/rdist-6.1.3.tar.gz
MD5 (rdist-6.1.3.tar.gz) = 8a76b880b023c5e648b7cb77b9608b9f
The README file in the distribution explains how to configure and
install this version of rdist.
We recommend that you configure this version of rdist to use rsh
instead of rcmd. Here is the relevant text from the README:
By default rdist uses rsh(1c) to make connections to remote
hosts. This has the advantage that rdist does not need to be
setuid to "root". This eliminates most potential security
holes. It has the disadvantage that it takes slightly more time
for rdist to connect to a remote host due to the added overhead
of doing a fork() and then running the rsh(1c) command.
Some sites with sufficient expertise use the ssh program in
conjunction with rdist, instead of using rcmd or rsh. If you have
the expertise, you may want to implement this configuration.
For further details on this option see "Ssh (Secure Shell) FAQ -
Frequently asked questions," Section 4.4, "Can I use rdist with ssh?"
It is available from
http://www.uni-karlsruhe.de/~ig25/ssh-faq/ssh-faq-4.html
For details on how to obtain ssh, see FAQ Section 3.4, "Where can I
obtain ssh?" This section can be found in
http://www.uni-karlsruhe.de/~ig25/ssh-faq/ssh-faq-3.html
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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)
=====================================
BSDI shipped a patch for this for our 2.1 release (U210-018) when
the original Bugtraq advisory was released. The 3.0 version of
rdist is not vulnerable and in fact is no longer even setuid.
Digital Equipment Corp.
=======================
This reported problem is not present for Digital's ULTRIX or Digital UNIX
Operating Systems Software.
DIGITAL EQUIPMENT CORPORATION
-----------------------------
FreeBSD, Inc.
=============
2.1.0 is vulnerable.
2.1.5, 2.1.6 and 2.1.7 are and 2.1-stable are not. In any case, upgrading
to 2.1.7 or even better, 2.1-stable should be considered.
If there is demand, we'll release a patch for 2.1.0
All 2.2 releases, 2.2-stable and FreeBSD-current are not vulnerable.
Hewlett-Packard Company
=======================
HP is -not- vulnerable; the problem didn't exist in 9.X, and has been fixed
in 10.X with Security Bulletin #36 (HPSBUX9608-036) last year. Patch
numbers change frequently because of cumulative patching, so please check
current patch ID information either by bulletin or by platform/release at
our HP Electronic Support Center in the "Security Patch Matrix," which is
updated every 24 hours.
1) From your Web browser, access the URL:
http://us-support.external.hp.com (US,Canada,Asia-Pacific,
and Latin-America)
http://europe-support.external.hp.com (Europe)
2) On the HP Electronic Support Center main screen, select the
hyperlink "Support Information Digests".
3) On the "Welcome to HP's Support Information Digests" screen,
under the heading "Register Now", select the appropriate hyperlink
"Americas and Asia-Pacific", or "Europe".
4) On the "New User Registration" screen, fill in the fields
for the User Information and Password and then select the button
labeled "Submit New User".
5) On the "User ID Assigned" screen, select the hyperlink
"Support Information Digests".
**Note what your assigned user ID and password are for future
reference.
6) You should now be on the "HP Support Information Digests Main"
screen. You might want to verify that your email address is
correct as displayed on the screen. From this screen, you may
also view/subscribe to the digests, including the security
bulletins digest.
To get a patch matrix of current HP-UX and BLS security
patches referenced by either Security Bulletin or Platform/OS,
click on following screens in order:
Technical Knowledge Database
Browse the HP Security Bulletins Archive
HP-UX Security Patch Matrix
IBM Corporation
===============
All versions of AIX are vulnerable to this buffer overflow. There is
no 3.2 fix. It is recommended that 3.2 customers upgrade to a higher
level. The following APARs will be available for AIX version 4
soon.
AIX 3.2: upgrade to 4.1.5 or higher
AIX 4.1: IX70876
AIX 4.2: IX70875
To Order
--------
APARs may be ordered using Electronic Fix Distribution (via FixDist)
or from the IBM Support Center. For more information on FixDist,
reference URL:
http://service.software.ibm.com/aixsupport/
or send e-mail to aixserv@austin.ibm.com with a subject of "FixDist".
IBM and AIX are registered trademarks of International Business Machines
Corporation.
NEC Corporation
===============
The following systems are NOT affected by this vulnerability:
UX/4800
UX/4800(64)
EWS-UX/V(Rel4.2MP)
EWS-UX/V(Rel4.2)
UP-UX/V(Rel4.2MP)
To report a new vulnerability, contact <UX48-security-support@nec.co.jp>.
The Santa Cruz Operation, Inc. (SCO)
====================================
SCO has determined that the following SCO operating systems are
not vulnerable:
- SCO CMW+ 3.0
- SCO Open Desktop/Open Server 3.0
- SCO OpenServer 5.0
- SCO UnixWare 2.1
Siemens-Nixdorf Informationssysteme AG
======================================
Siemens-Nixdorf does not ship rdist.
Silicon Graphics Inc. (SGI)
===========================
At this time, Silicon Graphics does not have any public information for the
rdist buffer overflow issue. Silicon Graphics has communicated with CERT/CC
and other external security parties and is actively investigating this
issue. When more Silicon Graphics information (including any possible
patches) is available for release, that information will be released via the
SGI security mailing list, wiretap.
For subscribing to the wiretap mailing list and other SGI security related
information, please refer to the Silicon Graphics Security Headquarters
website located at:
http://www.sgi.com/Support/security/security.html
Sun Microsystems, Inc.
======================
We are producing patches.
- ------------------------------------------------------------------------------
The CERT Coordination Center thanks Hiroshi Nakano of Ryukoku University,
Japan for reporting this problem. We also thank Wolfgang Ley of DFN-CERT
for his assistance with the Solutions section of the advisory.
- ------------------------------------------------------------------------------
[ End CERT Advisory ]
[ Start Sun Microsystems Advisory ]
________________________________________________________________________________
Sun Microsystems, Inc. Security Bulletin
Bulletin Number: #00179
Date: November 18, 1998
Cross-Ref:
Title: rdist
________________________________________________________________________________
The information contained in this Security Bulletin is provided "AS IS."
Sun makes no warranties of any kind whatsoever with respect to the information
contained in this Security Bulletin. ALL EXPRESS OR IMPLIED CONDITIONS,
REPRESENTATIONS AND WARRANTIES, INCLUDING ANY WARRANTY OF NON-INFRINGEMENT OR
IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE
HEREBY DISCLAIMED AND EXCLUDED TO THE EXTENT ALLOWED BY APPLICABLE LAW.
IN NO EVENT WILL SUN MICROSYSTEMS, INC. BE LIABLE FOR ANY LOST REVENUE,
PROFIT OR DATA, OR FOR DIRECT, SPECIAL, INDIRECT, CONSEQUENTIAL, INCIDENTAL
OR PUNITIVE DAMAGES HOWEVER CAUSED AND REGARDLESS OF ANY THEORY OF LIABILITY
ARISING OUT OF THE USE OF OR INABILITY TO USE THE INFORMATION CONTAINED IN
THIS SECURITY BULLETIN, EVEN IF SUN MICROSYSTEMS, INC. HAS BEEN ADVISED OF
THE POSSIBILITY OF SUCH DAMAGES.
If any of the above provisions are held to be in violation of applicable law,
void, or unenforceable in any jurisdiction, then such provisions are waived
to the extent necessary for this disclaimer to be otherwise enforceable in
such jurisdiction.
________________________________________________________________________________
1. Background
The rdist program is a setuid root utility that distributes files
from one host to another. Several buffer overflow vulnerabilities
have been discovered which could be exploited by an attacker to
gain root access.
2. Affected Supported Versions
Solaris(tm) versions: 2.6, 2.6_x86, 2.5.1, 2.5.1_x86, 2.5, 2.5_x86,
2.4, 2.4_x86 and 2.3
SunOS(tm) versions: 4.1.4 and 4.1.3_U1
3. Recommendations
Sun recommends that you install the respective patches immediately
on affected systems.
Operating System Patch ID
_________________ _________
Solaris 2.6 105667-02
Solaris 2.6_x86 105668-02
Solaris 2.5.1 103817-03
Solaris 2.5.1_x86 103818-03
Solaris 2.5 103815-03
Solaris 2.5_x86 103816-03
Solaris 2.4 103813-03
Solaris 2.4_x86 103814-03
Solaris 2.3 101494-04
SunOS 4.1.4 103824-04
SunOS 4.1.3_U1 103823-04
_______________________________________________________________________________
APPENDICES
A. Patches listed in this bulletin are available to all Sun customers via
World Wide Web at:
<URL:http://sunsolve.sun.com/sunsolve/pubpatches/patches.html>
B. Checksums for the patches listed in this bulletin are available via
World Wide Web at:
<URL:http://sunsolve.sun.com/sunsolve/pubpatches/patches.html>
C. Sun security bulletins are available via World Wide Web at:
<URL:http://sunsolve.sun.com/sunsolve/secbulletins>
D. Sun Security Coordination Team's PGP key is available via World Wide Web
at:
<URL:http://sunsolve.sun.com/sunsolve/secbulletins/SunSCkey.txt>
E. To report or inquire about a security problem with Sun software, contact
one or more of the following:
- Your local Sun answer centers
- Your representative computer security response team, such as CERT
- Sun Security Coordination Team. Send email to:
security-alert@sun.com
F. To receive information or subscribe to our CWS (Customer Warning System)
mailing list, send email to:
security-alert@sun.com
with a subject line (not body) containing one of the following commands:
Command Information Returned/Action Taken
_______ _________________________________
help An explanation of how to get information
key Sun Security Coordination Team's PGP key
list A list of current security topics
query [topic] The email is treated as an inquiry and is forwarded to
the Security Coordination Team
report [topic] The email is treated as a security report and is
forwarded to the Security Coordination Team. Please
encrypt sensitive mail using Sun Security Coordination
Team's PGP key
send topic A short status summary or bulletin. For example, to
retrieve a Security Bulletin #00138, supply the
following in the subject line (not body):
send #138
subscribe Sender is added to our mailing list. To subscribe,
supply the following in the subject line (not body):
subscribe cws your-email-address
Note that your-email-address should be substituted
by your email address.
unsubscribe Sender is removed from the CWS mailing list.
________________________________________________________________________________
Copyright 1998 Sun Microsystems, Inc. All rights reserved. Sun,
Sun Microsystems, Solaris and SunOS are trademarks or registered trademarks
of Sun Microsystems, Inc. in the United States and other countries. This
Security Bulletin may be reproduced and distributed, provided that this
Security Bulletin is not modified in any way and is attributed to
Sun Microsystems, Inc. and provided that such reproduction and distribution
is performed for non-commercial purposes.
[ End Sun Microsystems Advisory ]
______________________________________________________________________________
CIAC wishes to acknowledge the contributions of CERT 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: +1 510-422-8193
FAX: +1 510-423-8002
STU-III: +1 510-423-2604
E-mail: ciac@llnl.gov
For emergencies and off-hour assistance, DOE, DOE contractor sites,
and the NIH may contact CIAC 24-hours a day. During off hours (5PM -
8AM PST), call the CIAC voice number 510-422-8193 and leave a message,
or call 800-759-7243 (800-SKY-PAGE) to send a Sky Page. CIAC has two
Sky Page PIN numbers, the primary PIN number, 8550070, is for the CIAC
duty person, and the secondary PIN number, 8550074 is for the CIAC
Project Leader.
Previous CIAC notices, anti-virus software, and other information are
available from the CIAC Computer Security Archive.
World Wide Web: http://ciac.llnl.gov/
Anonymous FTP: ciac.llnl.gov (198.128.39.53)
Modem access: +1 (510) 423-4753 (28.8K baud)
+1 (510) 423-3331 (28.8K baud)
CIAC has several self-subscribing mailing lists for electronic
publications:
1. CIAC-BULLETIN for Advisories, highest priority - time critical
information and Bulletins, important computer security information;
2. CIAC-NOTES for Notes, a collection of computer security articles;
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4. SPI-NOTES, for discussion of problems and solutions regarding the
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Our mailing lists are managed by a public domain software package
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subscribe list-name
e.g., subscribe ciac-notes
You will receive an acknowledgment email immediately with a confirmation
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If you include the word 'help' in the body of an email to the above address,
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PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
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This document was prepared as an account of work sponsored by an
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Government nor the University of California nor any of their
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LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC)
H-97: SGI IRIX ftpd Signal Handling Vulnerability
H-98: SunOS automounter Vulnerability
H-99: SunOS, Solaris ifconfig ioctls Vulnerability
H-100: SunOS, Solaris libXt Vulnerability
H-101: FreeBSD procfs Vulnerability
H-102: SGI IRIX webdist.cgi, handler and wrap programs Vulnerabilities
H-103: HP-UX X11/Motif Libraries Vulnerability
H-104: HP-UX libXt Vulnerability
H-105: HP-UX vuefile, vuepad, dtfile, & dtpad Vulnerabilities
H-106: SGI IRIX LOCKOUT & login/scheme Vulnerabilities
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