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The U.S. Department of Energy
Computer Incident Advisory Capability
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INFORMATION BULLETIN
Sendmail MTA Buffer Overflow Vulnerability
[CERTŪ Advisory CA-2003-12]
March 31, 2003 15:00 GMT Number N-067
[REVISED 18 Sept 2003]
______________________________________________________________________________
PROBLEM: A remotely exploitable vulnerability has been identified
where address parsing code in sendmail does not adequately
check the length of email addresses. An email message with a
specially crafted address could trigger a stack overflow.
PLATFORM: Sendmail Pro (all versions)
Sendmail Switch 2.1 prior to 2.1.6
Sendmail Switch 2.2 prior to 2.2.6
Sendmail Switch 3.0 prior to 3.0.4
Sendmail for NT 2.X prior to 2.6.3
Sendmail for NT 3.0 prior to 3.0.4
Systems running open-source sendmail versions prior to 8.12.9,
including UNIX and Linux systems
IRIX 6.5.22 or patch 5287
DAMAGE: Successful exploitation of this vulnerability may cause a
denial-of-service condition or could allow an attacker to gain
the privileges of the sendmail daemon, typically root. Even
vulnerable sendmail servers on the interior of a given network
may be at risk since the vulnerability is triggered by the
contents of a malicious email message.
SOLUTION: Apply appropriate patches available from Sendmail, Inc., or
from your respective vendor.
Alternative: upgrade to Sendmail version 8.12.9.
Monitor CERT's Advisory for vendor information updates.
______________________________________________________________________________
VULNERABILITY The risk is HIGH. This vulnerability is message-oriented as
ASSESSMENT: opposed to connection-oriented. Connection-oriented defenses
such as packet filters and firewalls might not detect the
malicious e-mail. In particular, a non-sendmail mail transfer
agent (MTA) might pass on the malicious e-mail unchanged to
vulnerable MTAs.
______________________________________________________________________________
LINKS:
CIAC BULLETIN: http://www.ciac.org/ciac/bulletins/n-067.shtml
ORIGINAL BULLETIN: http://www.cert.org/advisories/CA-2003-12.html
PATCHES: http://www.sendmail.com/security/
http://www.sendmail.org
http://www.sendmail.org/8.12.9.html
ADDITIONAL LINK: ftp://patches.sgi.com/support/free/security/advisories/
20030803-01-P
______________________________________________________________________________
REVISION HISTORY: 09/18/03 - Added SGI Security Advisory's patch link and IRIX
to the Software section.
[***** Start CERTŪ Advisory CA-2003-12 *****]
CERTŪ Advisory CA-2003-12 Buffer Overflow in Sendmail
Original release date: March 29, 2003
Last revised: March 30, 2003
Source: CERT/CC
A complete revision history can be found at the end of this file.
Systems Affected
Sendmail Pro (all versions)
Sendmail Switch 2.1 prior to 2.1.6
Sendmail Switch 2.2 prior to 2.2.6
Sendmail Switch 3.0 prior to 3.0.4
Sendmail for NT 2.X prior to 2.6.3
Sendmail for NT 3.0 prior to 3.0.4
Systems running open-source sendmail versions prior to 8.12.9,
including UNIX and Linux systems
Overview
There is a vulnerability in sendmail that can be exploited to cause a
denial-of-service condition and could allow a remote attacker to execute
arbitrary code with the privileges of the sendmail daemon, typically root.
I. Description
There is a remotely exploitable vulnerability in sendmail that could allow an
attacker to gain control of a vulnerable sendmail server. Address parsing code
in sendmail does not adequately check the length of email addresses. An email
message with a specially crafted address could trigger a stack overflow. This
vulnerability was discovered by Michal Zalewski.
This vulnerability is different than the one described in CA-2003-07.
Most organizations have a variety of mail transfer agents (MTAs) at various
locations within their network, with at least one exposed to the Internet.
Since sendmail is the most popular MTA, most medium-sized to large organizations
are likely to have at least one vulnerable sendmail server. In addition, many
UNIX and Linux workstations provide a sendmail implementation that is enabled
and running by default.
This vulnerability is message-oriented as opposed to connection-oriented. That
means that the vulnerability is triggered by the contents of a specially-crafted
email message rather than by lower-level network traffic. This is important because
an MTA that does not contain the vulnerability will pass the malicious message
along to other MTAs that may be protected at the network level. In other words,
vulnerable sendmail servers on the interior of a network are still at risk, even
if the site's border MTA uses software other than sendmail. Also, messages capable
of exploiting this vulnerability may pass undetected through many common packet
filters or firewalls.
This vulnerability has been successfully exploited to cause a denial-of-service
condition in a laboratory environment. It is possible that this vulnerability
could be used to execute code on some vulnerable systems.
The CERT/CC is tracking this issue as VU#897604. This reference number corresponds
to CVE candidate CAN-2003-0161.
For more information, please see
http://www.sendmail.org
http://www.sendmail.org/8.12.9.html
http://www.sendmail.com/security/
For the latest information about this vulnerability, including the most recent
vendor information, please see
http://www.kb.cert.org/vuls/id/897604
This vulnerability is distinct from VU#398025.
II. Impact
Successful exploitation of this vulnerability may cause a denial-of-service condition
or allow an attacker to gain the privileges of the sendmail daemon, typically root.
Even vulnerable sendmail servers on the interior of a given network may be at risk
since the vulnerability is triggered by the contents of a malicious email message.
III. Solution
Apply a patch from Sendmail, Inc.
Sendmail has produced patches for versions 8.9, 8.10, 8.11, and 8.12. However,
the vulnerability also exists in earlier versions of the code; therefore, site
administrators using an earlier version are encouraged to upgrade to 8.12.9.
These patches, and a signature file, are located at
ftp://ftp.sendmail.org/pub/sendmail/prescan.tar.gz.uu
ftp://ftp.sendmail.org/pub/sendmail/prescan.tar.gz.uu.asc
Apply a patch from your vendor
Many vendors include vulnerable sendmail servers as part of their software
distributions. We have notified vendors of this vulnerability and recorded
the statements they provided in Appendix A of this advisory. The most recent
vendor information can be found in the systems affected section of VU#897604.
Enable the RunAsUser option
There is no known workaround for this vulnerability. Until a patch can be
applied, you may wish to set the RunAsUser option to reduce the impact of
this vulnerability. As a good general practice, the CERT/CC recommends
limiting the privileges of an application or service whenever possible.
Appendix A. - Vendor Information
This appendix contains information provided by vendors for this advisory.
As vendors report new information to the CERT/CC, we will update this
section and note the changes in our revision history. If a particular
vendor is not listed below, we have not received their comments.
Conectiva
Conectiva Linux 6.0, 7.0 and 8 contain sendmail and are vulnerable to this
issue, even though sendmail is no longer the default MTA in our distribution.
Updated packages will be announced to our mailing lists when ready.
Hewlett-Packard
SOURCE: Hewlett-Packard Company HP Services Software Security Response Team
x-ref: SSRT3531
At the time of writing this document, Hewlett Packard is currently
investigating the potential impact to HP's released Operating System
software products.
As further information becomes available HP will provide notice of
the availability of any necessary patches through standard security
bulletin announcements and be available from your normal HP Services
support channel.
Red Hat Inc.
Red Hat distributes sendmail in all Red Hat Linux distributions. We are
currently [Mar29] working on producing errata packages to correct this issue,
when complete these will be available along with our advisory at the URL below.
At the same time users of the Red Hat Network will be able to update their
systems using the 'up2date' tool.
Red Hat Linux:
http://rhn.redhat.com/errata/RHSA-2003-120.html
Red Hat Enterprise Linux:
http://rhn.redhat.com/errata/RHSA-2003-121.html
The Sendmail Consortium
The Sendmail Consortium recommends that sites upgrade to 8.12.9 whenever
possible. Alternatively, patches are available for 8.9, 8.10, 8.11, and 8.12
on http://www.sendmail.org/.
Sendmail, Inc.
All commercial releases including Sendmail Switch, Sendmail Advanced
Message Server (which includes the Sendmail Switch MTA), Sendmail for NT,
and Sendmail Pro are affected by this issue. Patch information is available
at http://www.sendmail.com/security/.
Wind River Systems Inc.
This vulnerability is addressed by the M500-008 patch for Platform for Server
Appliances 1.0 or BSD/OS 5.0 based systems. The M31--005 patch addresses this
problem for BSD/OS 4.3.1 or 4.3 systems, and the M420-034 addresses this problem
for BSD/OS 4.2 based systems.
Our thanks to Eric Allman, Claus Assmann, Greg Shapiro, and Dave Anderson of
Sendmail for reporting this problem and for their assistance in coordinating
the response to this problem. We also thank Michal Zalewski for discovering
this vulnerability.
Authors: Art Manion and Shawn V. Hernan
This document is available from: http://www.cert.org/advisories/CA-2003-12.html
CERT/CC Contact Information
Email: cert@cert.org
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
Postal address:
CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
U.S.A.
CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) / EDT(GMT-4) Monday
through Friday; they are on call for emergencies during other hours, on U.S.
holidays, and on weekends.
Using encryption
We strongly urge you to encrypt sensitive information sent by email. Our public PGP
key is available from
http://www.cert.org/CERT_PGP.key
If you prefer to use DES, please call the CERT hotline for more information.
Getting security information
CERT publications and other security information are available from our web site
http://www.cert.org/
To subscribe to the CERT mailing list for advisories and bulletins, send email
to majordomo@cert.org. Please include in the body of your message
subscribe cert-advisory
* "CERT" and "CERT Coordination Center" are registered in the U.S. Patent and
Trademark Office.
NO WARRANTY
Any material furnished by Carnegie Mellon University and the Software Engineering
Institute is furnished on an "as is" basis. Carnegie Mellon University makes no
warranties of any kind, either expressed or implied as to any matter including,
but not limited to, warranty of fitness for a particular purpose or merchantability,
exclusivity or results obtained from use of the material. Carnegie Mellon University
does not make any warranty of any kind with respect to freedom from patent,
trademark, or copyright infringement.
Conditions for use, disclaimers, and sponsorship information
Copyright 2003 Carnegie Mellon University.
Revision History
March 29, 2003: Initial release
March 29, 2003: Added Conectiva statement, reformated vendor statements
March 30, 2003: Added Wind River Systems and HP statements
[***** End CERTŪ Advisory CA-2003-12 *****]
_______________________________________________________________________________
CIAC wishes to acknowledge the contributions of CERT and Sendmail, Inc. 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
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CIAC services are available to DOE, DOE contractors, and the NIH. CIAC
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E-mail: ciac@ciac.org
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Anonymous FTP: ftp.ciac.org
PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing
communities receive CIAC bulletins. If you are not part of these
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constituencies can be obtained via WWW at http://www.first.org/.
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employees, makes any warranty, express or implied, or assumes any
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