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--- Begin Message --------BEGIN PGP SIGNED MESSAGE----- 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: [EMAIL PROTECTED] 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 [EMAIL PROTECTED] 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 Mar 03, 2003: Initial release -----BEGIN PGP SIGNATURE----- Version: PGP 6.5.8 iQCVAwUBPmOZEWjtSoHZUTs5AQGNUwP/YC0aRMqrFoLxUjG9pZIOBb98z8BFPfTW w/5u09rcW7WpH52XGaOWbu9PYtnLKtPaMrwevc38r6ILvZywasxdpUcUtR4W9XPZ 9EW4LYB1EaU81PLpzkQXWkVAhlX4vgHTU75oEcjfsacxXHlxtMYM1JpmyO8gvlnl pD4vLdvJqHE= =PfHu -----END PGP SIGNATURE-----
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