TUCoPS :: Unix :: General :: bt1134.txt

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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
 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
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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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