Remote Buffer Overflow in Sendmail

redhat에서 온 메일을 보고 아침부터 후다닥 패치하고 업데이트하고;;
정신없군요 -_-;; 이참에 qmail로갈까 고민입니다..--;

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CERT® Advisory CA-2003-07 Remote Buffer Overflow in Sendmail
Original release date: March 3, 2003
Last revised: March 3, 2003 13:36:45 EST
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.

Sun Microsystems
Solaris 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

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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.

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Authors: Jeffrey P. Lanza and Shawn V. Hernan

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This document is available from: http://www.cert.org/advisories/CA-2003-07.html

관련 링크: http://www.cert.org/advisories/CA-2003-07.html