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CERT Advisory 095
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=============================================================================
CERT(sm) Advisory CA-95:08
Original issue date: August 17, 1995
Last revised: August 30, 1996
Information previously in the README was inserted
into the advisory.
A complete revision history is at the end of this file.
Topic: Sendmail v.5 Vulnerability
- -----------------------------------------------------------------------------
The CERT Coordination Center has received reports of a vulnerability in
sendmail version 5. Although this version is several years old, it is still
in use. The vulnerability enables intruders to gain unauthorized privileges,
including root. We recommend installing all patches from your vendor or
moving to the current version of Eric Allman's sendmail (version 8.6.12).
The vulnerability is currently present in all versions of IDA sendmail and in
some vendors' releases of sendmail. The vendors who have reported to us are
listed in Section I.
We will update this advisory as we receive additional information.
Please check advisory files regularly for updates that relate to your site.
- -----------------------------------------------------------------------------
I. Description
In sendmail version 5, there is a vulnerability that intruders can
exploit to create files, append to existing files, or execute programs.
The vulnerability is currently present in all versions of IDA sendmail
and in some vendors' releases of sendmail.
Many vendors have previously installed upgrades or developed patches to
address the problem; some are working on patches now. Here is a summary
of vendors who reported to us as of the date of this advisory.
More details can be found in the appendix of this advisory, which we will
update as we receive additional information.
If you do not see your vendor's name or if you have questions about the
version of sendmail at your site, please contact your vendor directly.
Source or Vendor
----------------
Eric Allman
Apple Computer, Inc.
Berkeley SW. Design
Cray Research, Inc.
Data General Corp.
Digital Equipment Corp.
Harris Computer Systems
Hewlett-Packard Company
IBM Corporation
NEC Corporation
NeXT Computer, Inc.
Open Software Foundation
The Santa Cruz Operation
Silicon Graphics Inc.
Solbourne (Grumman)
Sun Microsystems, Inc.
Freely available and distributable software:
Users of the freely available operating systems Linux (systems using
sendmail rather than smail), NetBSD, and FreeBSD should upgrade to
sendmail 8.6.12.
II. Impact
Local and remote users can create files, append to existing files or run
programs on the system. Exploitation can lead to root access.
III. Solution
A. What to do
IDA users: Convert to sendmail 8.6.12.
Other users: Check the vendor information in the appendix of this
advisory.
Ensure that you have kept current with upgrades and patches from
your vendor.
If no patch is currently available, an alternative is to
install sendmail 8.6.12.
B. What you need to know about sendmail
1. Location
Sendmail is available by anonymous FTP from
ftp://ftp.cs.berkeley.edu/ucb/sendmail
ftp://info.cert.org/pub/tools/sendmail/sendmail.8.6.12
ftp://ftp.auscert.org.au/pub/mirrors/ftp.cs.berkeley.edu/ucb/sendmail
ftp://ftp.cert.dfn.de/pub/tools/net/sendmail/
The checksums are
MD5 (sendmail.8.6.12.base.tar.Z) = 31591dfb0dacbe0a7e06147747a6ccea
MD5 (sendmail.8.6.12.cf.tar.Z) = c60becd7628fad715df8f7e13dcf3cc6
MD5 (sendmail.8.6.12.misc.tar.Z) = 6212390ca0bb4b353e29521f1aab492f
MD5 (sendmail.8.6.12.patch) = 10961687c087ef30920b13185eef41e8
MD5 (sendmail.8.6.12.xdoc.tar.Z) = 8b2252943f365f303b6302b71ef9a841
2. Additional security
To restrict sendmail's program mailer facility, obtain
and install the sendmail restricted shell program (smrsh)
by Eric Allman (the original author of sendmail), following the
directions included with the program.
You should run smrsh with any UNIX system that is running sendmail,
regardless of vendor or version. Even with Eric Allman's sendmail
version 8.6.12, it is necessary for security-conscious sites to use
the smrsh program, as this carries out preprocessing of mail
headers and adds an extra layer of defense by controlling what
programs can be spawned by the incoming mail message. Note that
smrsh has now been included as part of the sendmail distribution
(effective with 8.7).
We also urge you to ensure that all patches are installed for the
distribution of sendmail you are using. Regardless of the vendor or
version of your UNIX systems and sendmail, the general advice to
"run the smrsh tool in conjunction with the most recently patched
version of sendmail for your system" holds true.
Copies of smrsh may be obtained via anonymous FTP from
ftp://info.cert.org/pub/tools/smrsh
ftp://ftp.uu.net/pub/security/smrsh
Checksum information
--------------------
BSD Sum
30114 5 README
25757 2 smrsh.8
46786 5 smrsh.c
System V Sum
56478 10 README
42281 4 smrsh.8
65517 9 smrsh.c
MD5 Checksum
MD5 (README) = fc4cf266288511099e44b664806a5594
MD5 (smrsh.8) = 35aeefba9714f251a3610c7b1714e355
MD5 (smrsh.c) = d4822ce7c273fc8b93c68e39ec67739c
3. Notes on installation
Depending upon the currently installed sendmail program, switching
to a different sendmail may require significant effort (such as
rewriting the sendmail.cf file.)
...........................................................................
Appendix: Vendor Information
Below is information we have received from vendors about the vulnerability in
sendmail version 5. If you do not see your vendor's name below, contact the
vendor directly for information.
- -------------
Eric Allman
Sendmail 8.6.10 and later are not vulnerable. The current version is 8.6.12.
Because the current version addresses vulnerabilities that appear in earlier
versions, it is a good idea to use 8.6.12.
Sendmail is available by anonymous FTP from
ftp://ftp.cs.berkeley.edu/ucb/sendmail
ftp://info.cert.org/pub/tools/sendmail/sendmail.8.6.12
ftp://ftp.auscert.org.au/pub/mirrors/ftp.cs.berkeley.edu/ucb/sendmail
ftp://ftp.cert.dfn.de/pub/tools/net/sendmail/
The checksums are
MD5 (sendmail.8.6.12.base.tar.Z) = 31591dfb0dacbe0a7e06147747a6ccea
MD5 (sendmail.8.6.12.cf.tar.Z) = c60becd7628fad715df8f7e13dcf3cc6
MD5 (sendmail.8.6.12.misc.tar.Z) = 6212390ca0bb4b353e29521f1aab492f
MD5 (sendmail.8.6.12.patch) = 10961687c087ef30920b13185eef41e8
MD5 (sendmail.8.6.12.xdoc.tar.Z) = 8b2252943f365f303b6302b71ef9a841
- -------------
Apple Computer, Inc.
[The following information also appeared in CERT advisory
CA-95:05, "Sendmail Vulnerabilities."]
An upgrade to A/UX version 3.1 (and 3.1.1) for these vulnerabilities is
available. The upgrade replaces the sendmail binary with the 8.6.10
version. It is available via anonymous FTP from ftp.support.apple.:
pub/apple_sw_updates/US/Unix/A_UX/supported/3.x/sendmail/
It is also available via anonymous FTP from abs.apple.com:
pub/abs/aws95/patches/sendmail/
In both cases the compressed binary has the following signature:
MD5 (sendmail.Z) = 31bb15604517630f46d7444a6cfab3f1
Uncompress(1) this file and replace the existing version in /usr/lib;
be sure to preserve the hard links to /usr/ucb/newaliases and
/usr/ucb/mailq, kill the running sendmail and restart.
Earlier versions of A/UX are not supported by this patch. Users of
previous versions are encouraged to update their system or compile
the latest version of sendmail available from ftp.cs.berkeley.edu.
Customers should contact their reseller for any additional information.
- -------------
Berkeley Software Design, Inc. (BSDI)
BSD/OS V2.0.1 is not vulnerable.
BSD/OS V2.0 users should install patch U200-011, available from
ftp.bsdi.com in bsdi/patches/U200-011.
BSDI Support contact information:
Phone: +1 719 536 9346
EMail: support@bsdi.com
- -------------
Cray Research, Inc.
not vulnerable
- -------------
Data General Corporation
DG/UX 5.4R3.00 and 5.4R3.10 (and associated Trusted version) are
vulnerable. Patches in progress now.
The upcoming release (R4.10 and R4.11) will not have this vulnerability
since these releases ship sendmail version 8.
- -------------
Digital Equipment Corp.
A patch for SENDMAIL (ULTSENDMAIL_EO1044 & OSFSENDMAIL_E01032) has been
available for some time, so if you have kept current with patches you are not
vulnerable to this particular reported problem.
If you have not applied the kits above, Digital Equipment Corporation strongly
urges customers to upgrade to the latest versions of ULTRIX V4.4 or DIGITAL
DEC OSF/1 V3.2, then apply the appropriate sendmail solution kit.
The above kits can be obtained through your normal Digital support channels or
by access (kit) request via DSNlink, DSIN, or DIA.
- -------------
Grumman Systems Support Corporation (GSSC)
GSSC now performs all Solbourne software and hardware support.
We recommend running sendmail 8.6.10 (or later revision.)
8.6.12 has proven reliable in production use on Solbourne systems.
We plan to release the Solbourne version of the Sun patch
when it becomes available.
Contact info:
ftp: ftp.nts.gssc.com
phone: 1-800-447-2861
email: support@nts.gssc.com
- -------------
Harris Computer Systems
not vulnerable
- -------------
Hewlett-Packard Company
Hewlett-Packard issued security bulletin #25 on April 2, 1995 announcing
patches and describing a fix. The patches are
PHNE_5402 (series 700/800, HP-UX 9.x), or
PHNE_5401 (series 700/800, HP-UX 8.x), or
PHNE_5384 (series 300/400, HP-UX 9.x), or
PHNE_5383 (series 300/400, HP-UX 8.x), or
PHNE_5387 (series 700, HP-UX 9.09), or
PHNE_5388 (series 700, HP-UX 9.09+), or
PHNE_5389 (series 800, HP-UX 9.08)
The bulletin is available from the HP SupportLine and from http://www.hp.com
in the HPSL category and from http://support.mayfield.hp.com.
Patches may be obtained from HP via FTP (this is NOT anonymous FTP) or the HP
SupportLine. To obtain HP security patches, you must first register with the
HP SupportLine. The registration instructions are available via anonymous FTP
at info.cert.org in the file "pub/vendors/hp/supportline_and_patch_retrieval".
HP SupportLine: 1-415-691-3888
phone: 1-415-691-3680
telnet/ftp: support.mayfield.hp.com
WWW: http://www.hp.com
http://support.mayfield.hp.com.
- -------------
IBM Corporation
A patch (ptf U425863) has been available for AIX 3.2 for some time.
To determine if you have this ptf on your system, run the following command:
% lslpp -lB U425863
If you have not already applied the patch, you can order it from IBM as APAR
ix40304 To order APARs from IBM in the U.S., call 1-800-237-5511. To obtain
APARs outside of the U.S., contact your local IBM representative.
- -------------
NEC Corporation
OS Version Status
- ------------------ ------------ ------------------------------
EWS-UX/V(Rel4.0) R1.x - R6.x vulnerable
EWS-UX/V(Rel4.2) R7.x - R10.x vulnerable
patch available
EWS-UX/V(Rel4.2MP) R10.x vulnerable
patch available
UP-UX/V R1.x - R4.x vulnerable
UP-UX/V(Rel4.2MP) R5.x - R7.2 vulnerable
patch available except for R5.x
UX/4800 R11.x not vulnerable
Contacts for further information:
e-mail:UXcert-CT@d2.bsd.nes.nec.co.jp
- -------------
NeXT Computer, Inc.
The sendmail executables included with all versions of NEXTSTEP up
to and including release 3.3 are vulnerable to this problem. The
SendmailPatch previously released for NEXTSTEP 3.1 and 3.2 is also
vulnerable.
An updated patch is planned which will address this vulnerability.
The availability of this patch will be indicated in the NeXTanswers
section of http://www.next.com/. For further information you may
contact NeXT's Technical Support Hotline at (+1-800-955-NeXT) or
via email to ask_next@NeXT.com.
- -------------
Open Software Foundation
not vulnerable
- -------------
The Santa Cruz Operation
Support Level Supplement (SLS) net382e, contains a patched version of
sendmail for the following releases:
SCO TCP/IP Runtime System Release 1.2.1
SCO Open Desktop Lite Release 3.0
SCO Open Desktop Release 3.0
SCO Open Server Network System Release 3.0
SCO Open Server Enterprise System Release 3.0
SCO OpenServer 5 contains Sendmail version 8.6.8, and contains fixes
to all problems reported in this and previous sendmail advisories.
Users of previous releases should consider updating.
NOTE: The MMDF (M)ulti-Channel (M)emorandum (D)istribution
(F)acility is the default mail system on SCO systems. The MMDF mail
system is not affected by any of the problems mentioned in these
advisories. Administrators who wish to use sendmail must specifically
configure the system to do so during or after installation.
To acquire SLS net382e:
Anonymous ftp on the Internet:
==============================
ftp://ftp.sco.COM/SLS/net382e.Z (disk image)
ftp://ftp.sco.COM/SLS/net382e.ltr.Z (documentation)
Anonymous uucp:
===============
United States:
- --------------
sosco!/usr/spool/uucppublic/SLS/net382e.Z (disk image)
sosco!/usr/spool/uucppublic/SLS/net382e.ltr.Z (documentation)
United Kingdom:
- ---------------
scolon!/usr/spool/uucppublic/SLS/net382e.Z (disk image)
scolon!/usr/spool/uucppublic/SLS/net382e.ltr.Z (documentation)
The telephone numbers and login names for the machines sosco and scolon
are provided with the default /usr/lib/uucp/Systems file shipped with
every SCO system.
The checksums for the files listed above are as follows:
file sum -r md5
=========================== ================================
net382e.Z: 29715 1813 41efeaaa855e4716ed70c12018014092
net382e.ltr.Z 52213 14 287ba6131519cba351bc58cb32880fda
The Support Level Supplement is also available on floppy media from SCO
Support at the following telephone numbers:
USA/Canada: 6am-5pm Pacific Daylight Time (PDT)
-----------
1-408-425-4726 (voice)
1-408-427-5443 (fax)
Pacific Rim, Asia, and Latin American customers: 6am-5pm Pacific
------------------------------------------------ Daylight Time
(PDT)
1-408-425-4726 (voice)
1-408-427-5443 (fax)
Europe, Middle East, Africa: 9am-5:00pm Greenwich Mean Time (GMT)
----------------------------
+44 1923 816344 (voice)
+44 1923 817781 (fax)
For further information, contact SCO at one of the above numbers,
send electronic mail to support@sco.COM, or see the SCO Web Page at:
http://www.sco.COM.
- -------------
Silicon Graphics Inc.
On February 22, 1995, Silicon Graphics issued security advisory 19950201
addressing sendmail issues being raised at the time and previous older
version sendmail issues. Patches are still available and as part of these
patches, sendmail version 8.6.12 is provided as standard. At the time
of this writing here is the patch information.
**** IRIX 3.x ****
Unfortunately, Silicon Graphics Inc, no longer supports the IRIX 3.x
operating system and therefore has no patches or binaries to provide.
However, two possible actions still remain: 1) upgrade the system to a
supported version of IRIX (see below) and then install the binary/patch
or 2) obtain the sendmail source code from anonymous FTP at
ftp.cs.berkeley.edu and compile the program manually.
**** IRIX 4.x ****
For the IRIX operating system version 4.x, a manually installable
binary replacement has been generated and made available via anonymous
ftp and/or your service/support provider. The binary is sendmail.new.Z
and is installable on all 4.x platforms.
Binaries can be found at ftp://ftp.sgi.com/ftp/Patches/4.x
but not at the alternative location, ~ftp/Security.
##### Checksums as of August 17, 1995, 5 p.m. EDT ####
Filename: sendmail.new.Z
Algorithm #1 (sum -r): 30749 422 sendmail.new.Z
Algorithm #2 (sum): 62511 422 sendmail.new.Z
MD5 checksum: AB327D85D40085D74E9C230EB1A002C3
Note: SGI plans to upgrade the IRIX 4.x patch soon. If there is a difference
between the checksums of the file you obtain and those reported here, you
should rely on SGI's <sendmail-filename>.pgp.and.chksums file.
After obtaining the binary, it may be installed with the instructions
below:
1) Become the root user on the system.
% /bin/su -
Password:
#
2) Stop the current mail processes.
# /etc/init.d/mail stop
3) Rename the current sendmail binary to a temporary
name.
# mv /usr/lib/sendmail /usr/lib/sendmail.stock
4) Change permissions on the old sendmail binary so it can not
be used anymore.
# chmod 0400 /usr/lib/sendmail.stock
5) Uncompress the binary.
# uncompress /tmp/sendmail.new.Z
6) Put the new sendmail binary into place (in the example
here the binary was retrieved via anonymous ftp and put
in /tmp)
# mv /tmp/sendmail.new /usr/lib/sendmail
7) Insure the correct permissions and ownership on the new
sendmail.
# chown root.sys /usr/lib/sendmail
# chmod 4755 /usr/lib/sendmail
8) Restart the mail system with the new sendmail binary in place.
# /etc/init.d/mail start
9) Return to normal user level.
# exit
**** IRIX 5.0.x, 5.1.x ****
For the IRIX operating systems versions 5.0.x, 5.1.x, an upgrade
to 5.2 or better is required first. When the upgrade is completed,
then the patch described in the next section "**** IRIX 5.2, 5.3, 6.0,
6.0.1 ***" can be applied.
**** IRIX 5.2, 5.3, 6.0, 6.0.1 ****
For the IRIX operating system versions 5.2, 5.3, 6.0 and 6.0.1, an
inst-able patch has been generated and made available via anonymous
ftp and/or your service/support provider. The patch is number 332
and will install on IRIX 5.2, 5.3, 6.0 and 6.0.1 .
The SGI anonymous ftp site is ftp.sgi.com (192.48.153.1). Patch
332 can be found in the following directories on the ftp server:
~ftp/Security
or
~ftp/Patches/5.2
~ftp/Patches/5.3
~ftp/Patches/6.0
~ftp/Patches/6.0.1
For obtaining security information, patches or assistance, please
contact your SGI support provider.
If there are questions about this patch information, email can be
sent to cse-security-alert@csd.sgi.com .
For reporting new SGI security issues, email can be sent to
security-alert@sgi.com .
- -------------
Solbourne
see Grumman Systems Support Corporation
- -------------
Sun Microsystems, Inc.
Solaris 2.x is not vulnerable.
Sun OS 4.1.3, 4.1.37_u1, and 4.1.4 are vulnerable, and a patch will be
available soon.
This patch can be obtained from local Sun Answer Centers and through anonymous
FTP from ftp.uu.net in the /systems/sun/sun-dist directory. In Europe, the
patch is available from mcsun.eu.net (192.16.202.1) in the /sun/fixes
directory.
- ---------------------------------------------------------------------------
The CERT Coordination Center staff thanks the vendors listed in this
advisory, along with Karl Strickland and Neil Woods for their support
in the development of this advisory.
- ---------------------------------------------------------------------------
If you believe that your system has been compromised, contact the CERT
Coordination Center or your representative in the Forum of Incident
Response and Security Teams (FIRST).
If you wish to send sensitive incident or vulnerability information to
CERT staff by electronic mail, we strongly advise that the email be
encrypted. The CERT Coordination Center can support a shared DES key, PGP
(public key available via anonymous FTP on info.cert.org), or PEM (contact
CERT staff for details).
Internet email: cert@cert.org
Telephone: +1 412-268-7090 (24-hour hotline)
CERT personnel answer 8:30 a.m.-5:00 p.m. EST(GMT-5)/EDT(GMT-4),
and are on call for emergencies during other hours.
Fax: +1 412-268-6989
Postal address: CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh, PA 15213-3890
USA
CERT advisories and bulletins are posted on the USENET newsgroup
comp.security.announce. If you would like to have future advisories and
bulletins mailed to you or to a mail exploder at your site, please send mail
to cert-advisory-request@cert.org.
Past advisories, CERT bulletins, information about FIRST representatives, and
other information related to computer security are available for anonymous
FTP from info.cert.org.
Copyright 1995, 1996 Carnegie Mellon University
This material may be reproduced and distributed without permission provided it
is used for noncommercial purposes and the copyright statement is included.
CERT is a service mark of Carnegie Mellon University.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Revision history
Aug. 07, 1996 Information previously in the README was inserted
into the advisory.
Nov. 07, 1995 Sec. III.B.2 - emphasized that smrsh should be run with all
versions of sendmail.
Sep. 20, 1995 Sec. I - changed "public domain" to "freely available."
Appendix - added an entry for Data General.
Aug. 21, 1995 Sec. III.B and appendix, Eric Allman - added a German FTP site
for sendmail and corrected the URL for Australia.
Appendix, Silicon Graphics - corrected information for 4.x
Appendix, Sun - corrected a typo in the OS number
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