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CERT® Advisory CA-2003-07 Remote Buffer Overflow in SendmailOriginal release date: March 3, 2003Last revised: June 09, 2003 Source: CERT/CC A complete revision history can be found at the end of this file. Systems Affected
OverviewThere is a vulnerability in sendmail that may allow remote attackers to gain the privileges of the sendmail daemon, typically root. I. DescriptionResearchers 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:
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
II. ImpactSuccessful 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. SolutionApply a patch from SendmailSendmail 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
Apply a patch from your vendorMany 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 optionThere 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 InformationThis 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/OSWind 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 SystemsCisco 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. DebianUpdated packages for sendmail and sendmail-wide will be available at http://www.debian.org/security/2003/dsa-257 Hewlett-Packard Company
SOURCE:
Hewlett-Packard Company
HP Services
Software Security Response Team
x-ref: SSRT3469
HP released security bulletins for this issue on 03 March 2003
and recently updated 11 March 2003 for Internet Express and
AVFW98.
View at www.hp.com and in the search window type SSRT3469
For HP-UX use your normal ITRC access and select Security
Bulletin HPSBUX0302-246
This problem affects supported versions of HP-UX,
HP Tru64 UNIX/TruCluster Server,
HP AlphaServer SC (Sierra Cluster) V2.5,
HP Internet Express,
HP AltaVista Firewall (AVFW98 / Raptor EC).
NOTE: This problem does not impact
HP NonStop Servers nor HP OpenVMS.
Hitachi, Ltd.Hitachi's GR2000 gigabit router series - is NOT vulnerable, because it does not support sendmail. Hitachi's HI-UX/WE2 - is NOT vulnerable. If you need technical information, please contact Hitachi's support. IBM CorporationThe AIX operating system is vulnerable to the sendmail issues discussed in releases 4.3.3, 5.1.0 and 5.2.0. IBM provides the following official fixes:
Please contact your local IBM AIX support center for any assistance. Juniper NetworksSendmail does not ship with any Juniper Networks product, so there is no vulnerability to this issue. LotusIBM has determined that Lotus products, including Notes and Domino, are not vulnerable to the sendmail issues reported by ISS. MandrakeSoftMandrakeSoft has issued updated sendmail packages that are not vulnerable to this problem by using the patches provided by the sendmail development team. Users can use urpmi or the Software Manager to upgrade packages. The web advisory is available: http://www.mandrakesecure.net/en/advisories/advisory.php?name=MDKSA-2003:028 Nortel NetworksThe following Nortel Networks Wireless products are potentially affected by the vulnerabilities identified in CERT Advisory CA-2003-07:
The following Nortel Networks Enterprise Voice IVR products are potentially affected by the vulnerabilities identified in CERT Advisory CA-2003-07:
All the above products deploy Sendmail; it should not be disabled on these products. For all of the above products Nortel Networks recommends applying the latest Sun Microsystems patches in accordance with that vendor's recommendations. To avoid applying patches twice, please ensure that the Sun Microsystems patch applied also addresses the vulnerability identified in CERT Advisory CA-2003-12. The following Nortel Networks Succession products are potentially affected by the vulnerability identified in CERT Advisory CA-2003-07:
A product bulletin will be issued shortly. Sendmail has been disabled in SN06 and therefore SN06 is not vulnerable. A patch for SN05 is currently under development that will disable Sendmail in SN05 so that it will not be affected by the vulnerability identified in CERT Advisory CA-2003-07. The availability date for the SN05 patch is still to be determined. For more information please contact Nortel at:
Openwall GNU/*/LinuxOpenwall GNU/*/Linux is not vulnerable. We use Postfix as the MTA, not sendmail. PostfixPostfix 2.0.6 duplicates the Sendmail 8.12.8 fix to in order to help protect downstream Sendmail systems against exploitation of this vulnerability. Patches are also available for several older Postfix releases. For download information, please see http://www.postfix.org/. 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 Sequent Computer Systems (IBM)For information please contact IBM Service at 1-800-IBM-SERV. SGISGI 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 ConsortiumThe 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. Sun MicrosystemsSolaris 2.6, 7, 8 and 9 are vulnerable to VU#398025. Sun will be publishing a Sun Alert for the issue at the following location shortly: http://sunsolve.Sun.COM/pub-cgi/retrieve.pl?doc=fsalert/51181 The patches listed in the Sun Alert will be available from: http://sunsolve.sun.com/securitypatch SyntegraNone of Syntegra's mail products, including IntraStore, eMail Sentinel and Mail*Hub are vulnerable to this defect. Xerox CorporationA response to this advisory is available from our web site: http://www.xerox.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
Phone: +1 412-268-7090 (24-hour hotline) Fax: +1 412-268-6989 Postal address: 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 encryptionWe strongly urge you to encrypt sensitive information sent by email. Our public PGP key is available from If you prefer to use DES, please call the CERT hotline for more information. Getting security informationCERT publications and other security information are available from our web site
* "CERT" and "CERT Coordination Center" are registered in the U.S. Patent and Trademark Office.
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Copyright 2003 Carnegie Mellon University. Revision History
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