10709357 2003-09-18 10:37 -0400 /303 rader/ CERT Advisory <cert-advisory@cert.org>
Sänt av: bellman@lysator.liu.se
Importerad: 2003-09-18 16:57 av Brevbäraren
Extern mottagare: cert-advisory@cert.org
Mottagare: Bugtraq (import) <29072>
Sänt: 2003-09-18 17:55
Ärende: CERT Advisory CA-2003-25 Buffer Overflow in Sendmail
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From: CERT Advisory <cert-advisory@cert.org>
To: cert-advisory@cert.org
Message-ID: <CA-2003-25.1@cert.org>
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CERT Advisory CA-2003-25 Buffer Overflow in Sendmail
Original issue date: September 18, 2003
Last revised: --
Source: CERT/CC
A complete revision history is at the end of this file.
Systems Affected
* Systems running open-source sendmail versions prior to 8.12.10,
including UNIX and Linux systems
* Commercial releases of sendmail including Sendmail Switch,
Sendmail Advanced Message Server (SAMS), and Sendmail for NT
Overview
A vulnerability in sendmail could allow a remote attacker to
execute arbitrary code with the privileges of the sendmail
daemon, typically root.
I. Description
Sendmail is a widely deployed mail transfer agent (MTA). Many UNIX
and Linux systems provide a sendmail implementation that is
enabled and running by default. Sendmail contains a
vulnerability in its address parsing code. An error in the
prescan() function could allow an attacker to write past the
end of a buffer, corrupting memory structures. Depending on
platform and operating system architecture, the attacker may be
able to execute arbitrary code with a specially crafted email
message.
This vulnerability is different than the one described in
CA-2003-12.
The email attack vector is message-oriented as opposed to
connection-oriented. This 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 may 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 packet filters or firewalls.
Further information is available in VU#784980. Common
Vulnerabilities and Exposures (CVE) refers to this issue as
CAN-2003-0694.
II. Impact
Depending on platform and operating system architecture, a remote
attacker could execute arbitrary code with the privileges of the
sendmail daemon. Unless the RunAsUser option is set, Sendmail
typically runs as root.
III. Solution
Upgrade or apply a patch
This vulnerability is resolved in Sendmail 8.12.10. Sendmail has
also released a patch that can be applied to Sendmail 8.9.x
through 8.12.9. Information about specific vendors is available
in Appendix A. and in the Systems Affected section of VU#784980.
Sendmail 8.12.10 is designed to correct malformed messages that
are transferred by the server. This should help protect other
vulnerable sendmail servers.
Enable the RunAsUser option
While there is no known complete workaround, consider setting
the RunAsUser option to reduce the impact of this
vulnerability. It is typically considered to be a good
security practice to limit the privileges of applications and
services whenever possible.
Appendix A. Vendor Information
This appendix contains information provided by vendors. When
vendors report new information, this section is updated, and the
changes are noted in the revision history. If a vendor is not
listed below, we have not received their direct
statement. Further vendor information is available in the Systems
Affected section of VU#784980.
Debian
The sendmail and sendmail-wide packages are vulnerable to
this issue. Updated packages are being prepared and will be
available soon.
F5 Networks
BIG-IP and 3-DNS products are not vulnerable.
IBM
The AIX Security Team is aware of the issues discussed in
CERT Vulnerability Note VU#784980.
The following APARs will be released to address this issue:
APAR number for AIX 4.3.3: IY48659 (available approx. 10/03/03)
APAR number for AIX 5.1.0: IY48658 (available approx. 10/15/03)
APAR number for AIX 5.2.0: IY48657 (available approx. 10/29/03)
An e-fix will be available shortly. The e-fix will be
available from:
ftp://ftp.software.ibm.com/aix/efixes/security/sendmail_4_efix.tar.Z
This vendor statement will be updated when the e-fix
becomes available.
Lotus
This is a sendmail-specific issue that does not affect any
Lotus products.
Network Appliance
NetApp products are not vulnerable to this problem.
NetBSD
NetBSD-current ships with sendmail 8.12.9 since June 1,
2003. The patch was applied on September 17, 2003. In the
near future we would upgrade to sendmail 8.12.10.
Our official releases, such as NetBSD 1.6.1, are also
affected (they ship with older version of sendmail). They will
be patched as soon as possible. We would issue NetBSD Security
Advisory on this matter.
Openwall GNU/*/Linux
Openwall GNU/*/Linux is not vulnerable. We ship Postfix, not
Sendmail.
Red Hat
Red Hat Linux and Red Hat Enterprise Linux ship with a
Sendmail package vulnerable to these issues. Updated Sendmail
packages are available along with our advisory at the URLs
below. Users of the Red Hat Network can update their systems
using the 'up2date' tool.
Red Hat Linux:
http://rhn.redhat.com/errata/RHSA-2003-283.html
Red Hat Enterprise Linux:
http://rhn.redhat.com/errata/RHSA-2003-284.html
The Sendmail Consortium
The Sendmail Consortium recommends that sites upgrade to
8.12.10 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/.
Sun
Sun acknowledges that our recent release of sendmail 8.12.10
is affected by this issue on Solaris releases S7, S8 and S9.
A Sun Alert for this issue will be isuued very soon which will
then be available from:
http://sunsolve.Sun.COM/pub-cgi/retrieve.pl?doc=fsalert/56860
There are no patches available at this time. The Sun Alert will
be updated with the patch information as it becomes
available. Please refer to the Sun Alert when available, for
more information.
SuSE
SuSE products shipping sendmail are affected. Update packages
that fix the vulnerability are being prepared and will be
published shortly.
Appendix B. References
* CERT/CC Vulnerability Note VU#784980 -
<http://www.kb.cert.org/vuls/id/784980>
* Michal Zalewski's post to BugTraq -
<http://www.securityfocus.com/archive/1/337839>
* Sendmail 8.12.10 - <http://www.sendmail.org/8.12.10.html>
* Sendmail patch for 8.12.9 -
<http://www.sendmail.org/patches/parse8.359.2.8>
* Sendmail 8.12.10 announcement -
<http://archives.neohapsis.com/archives/sendmail/2003-q3/0002.html
>
* Sendmail Secure Install -
<http://www.sendmail.org/secure-install.html>
_________________________________________________________________
This vulnerability was discovered by Michal Zalewski. Thanks to Claus
Assmann and Eric Allman of Sendmail for their help in preparing this
document.
_________________________________________________________________
Feedback can be directed to the author, Art Manion.
______________________________________________________________________
This document is available from:
http://www.cert.org/advisories/CA-2003-25.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
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* "CERT" and "CERT Coordination Center" are registered in the
U.S. Patent and Trademark Office.
______________________________________________________________________
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and the Software Engineering Institute is furnished on an
"as is" basis. Carnegie Mellon University makes no warranties of
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______________________________________________________________________
Conditions for use, disclaimers, and sponsorship information
Copyright 2003 Carnegie Mellon University.
Revision History
September 18, 2003: Initial release
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