[SECURITY-L] CERT Advisory CA-2003-07 Remote Buffer Overflow in Sendmail
Silvana Mieko Misuta
mieko em ccuec.unicamp.br
Qui Mar 6 08:54:36 -03 2003
Subject: CERT Advisory CA-2003-07 Remote Buffer Overflow in
Sendmail
Date: Mon, 3 Mar 2003 13:07:24 -0500
From: CERT Advisory <cert-advisory em cert.org>
Organization: CERT(R) Coordination Center - +1 412-268-7090
To: cert-advisory em cert.org
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CERT Advisory CA-2003-07 Remote Buffer Overflow in Sendmail
Original release date: March 3, 2003
Last revised: --
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 2.1.5
* Sendmail Switch 2.2 prior to 2.2.5
* Sendmail Switch 3.0 prior to 3.0.3
* Sendmail for NT 2.X prior to 2.6.2
* Sendmail for NT 3.0 prior to 3.0.3
* Systems running open-source sendmail versions prior to
8.12.8,
including UNIX and Linux systems
Overview
There is a vulnerability in sendmail that may allow remote
attackers
to gain the privileges of the sendmail daemon, typically root.
I. Description
Researchers at Internet Security Systems (ISS) have discovered
a
remotely exploitable vulnerability in sendmail. This
vulnerability
could allow an intruder to gain control of a vulnerable
sendmail
server.
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.
Sendmail has indicated to the CERT/CC that this vulnerability has
been
successfully exploited in a laboratory environment. We do not
believe
that this exploit is available to the public. However,
this
vulnerability is likely to draw significant attention from
the
intruder community, so the probability of a public exploit is high.
A successful attack against an unpatched sendmail system will
not
leave any messages in the system log. However, on a patched system,
an
attempt to exploit this vulnerability will leave the following
log
message:
Dropped invalid comments from header address
Although this does not represent conclusive evidence of an attack,
it
may be useful as an indicator.
A patched sendmail server will drop invalid headers, thus
preventing
downstream servers from receiving them.
The CERT/CC is tracking this issue as VU#398025. This reference
number
corresponds to CVE candidate CAN-2002-1337.
For more information, please see
http://www.sendmail.org
http://www.sendmail.org/8.12.8.html
http://www.sendmail.com/security/
http://www.iss.net/issEn/delivery/xforce/alertdetail.jsp?oid=21950
http://www.kb.cert.org/vuls/id/398025
II. Impact
Successful exploitation of this vulnerability may 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 from the contents of
a
malicious email message.
III. Solution
Apply a patch from Sendmail
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 8.12.8. These patches are located at
ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.12.security.cr.patch
ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.11.6.security.cr.patch
ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.9.3.security.cr.patch
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 their responses in the systems affected section
of
VU#398025. Several vendors have provided a statement for
direct
inclusion in this advisory; these statements are available in
Appendix
A.
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.
Apple Computer, Inc.
Security Update 2003-03-03 is available to fix this issue.
Packages
are available for Mac OS X 10.1.5 and Mac OS X 10.2.4. It should
be
noted that sendmail is not enabled by default on Mac OS X, so
only
those systems which have explicitly enabled it are susceptible to
the
vulnerability. All customers of Mac OS X, however, are encouraged
to
apply this update to their systems.
Avaya, Inc.
Avaya is aware of the vulnerability and is investigating impact.
As
new information is available this statement will be updated.
BSD/OS
Wind River Systems has created patches for this problem which
are
available from the normal locations for each release. The
relevant
patches are M500-006 for BSD/OS version 5.0 or the Wind River
Platform
for Server Appliances 1.0, M431-002 for BSD/OS 4.3.1, or M420-032
for
BSD/OS 4.2 systems.
Cisco Systems
Cisco is investigating this issue. If we determine any of our
products
are vulnerable that information will be available
at:
http://www.cisco.com/go/psirt
Cray Inc.
The code supplied by Cray, Inc. in Unicos, Unicos/mk, and
Unicos/mp
may be vulnerable. Cray has opened SPRs 724749 and 724750
to
investigate.
Cray, Inc. is not vulnerable for the MTA systems.
Hewlett-Packard Company
SOURCE:
Hewlett-Packard Company
HP Services
Software Security Response Team
x-ref: SSRT3469 sendmail
HP will provide notice of the availability of patches through
standard
security bulletin announcements and be available from your normal HP
Services support channel.
IBM Corporation
The AIX operating system is vulnerable to the sendmail
issues
discussed in releases 4.3.3, 5.1.0 and 5.2.0.
A temporary patch is available through an efix package which can
be
found at
ftp://ftp.software.ibm.com/aix/efixes/security/sendmail_efix.tar.Z
IBM will provide the following official fixes:
APAR number for AIX 4.3.3: IY40500 (available
approx.
03/12/2003)
APAR number for AIX 5.1.0: IY40501 (available
approx.
04/28/2003)
APAR number for AIX 5.2.0: IY40502 (available
approx.
04/28/2003)
Openwall GNU/*/Linux
Openwall GNU/*/Linux is not vulnerable. We use Postfix as the MTA,
not
sendmail.
Red Hat Inc.
Updated sendmail packages that are not vulnerable to this issue
are
available for Red Hat Linux, Red Hat Advanced Server, and Red
Hat
Advanced Workstation. Red Hat Network users can update their
systems
using the 'up2date' tool.
Red Hat Linux:
http://rhn.redhat.com/errata/RHSA-2003-073.html
Red Hat Linux Advanced Server, Advanced Workstation:
http://rhn.redhat.com/errata/RHSA-2003-074.html
SGI
SGI acknowledges VU#398025 reported by CERT and has released
an
advisory to address the vulnerability on IRIX.
Refer to SGI Security Advisory 20030301-01-P available
from
ftp://patches.sgi.com/support/free/security/advisories/20030301-01-P
or http://www.sgi.com/support/security/.
The Sendmail Consortium
The Sendmail Consortium suggests that sites upgrade to 8.12.8
if
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.
_________________________________________________________________
Our thanks to Internet Security Systems, Inc. for discovering
this
problem, and to Eric Allman, Claus Assmann, and Greg Shapiro
of
Sendmail for notifying us of this problem. We thank both groups
for
their assistance in coordinating the response to this problem.
_________________________________________________________________
Authors: Jeffrey P. Lanza and Shawn V. Hernan
______________________________________________________________________
This document is available from:
http://www.cert.org/advisories/CA-2003-07.html
______________________________________________________________________
CERT/CC Contact Information
Email: cert em 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
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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.
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______________________________________________________________________
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Copyright 2003 Carnegie Mellon University.
Revision History
Mar 03, 2003: Initial release
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