CERT/CC Vulnerability Note VU#784980

Overview

Sendmail contains a buffer overflow vulnerability in code that parses email addresses. This vulnerability could allow a remote attacker to execute arbitrary code or cause a denial of service on a vulnerable system.

Description

Sendmail is a widely used mail transfer agent (MTA). There is a buffer overflow vulnerability in code that parses email addresses.

When processing email messages, sendmail creates tokens from address elements (user, host, domain). The code that performs this function (prescan() in parseaddr.c) contains a vulnerability that could allow a remote attacker to overwrite memory structures and execute arbitary code. The attacker could exploit this vulnerability using an email message with a specially crafted address. Such a message could be passed through MTAs that are not vulnerable.

Further information is available in a message by Michal Zalewski.

This is a different vulnerability than the one described in CA-2003-12/VU#897604.

Impact

A remote attacker could execute arbitrary code with the privileges of the Sendmail process, typically root. The attacker may also be able to cause a denial of service.

Solution

Upgrade or Patch
Upgrade or apply a patch as specified by your vendor. Sendmail has released version 8.12.10 and a patch that resolve this issue.

Enable RunAsUser

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.

Vendor Information

784980

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Apple Computer Inc. Affected

Conectiva Affected

Debian Affected

FreeBSD Affected

Gentoo Linux Affected

Hewlett-Packard Company Affected

IBM Affected

IBM eServer Affected

MandrakeSoft Affected

NETBsd Affected

OpenPKG Affected

Red Hat Inc. Affected

SGI Affected

Secure Computing Corporation Affected

Sendmail Inc. Affected

Slackware Affected

SuSE Inc. Affected

Sun Microsystems Inc. Affected

The Sendmail Consortium Affected

Notified: September 17, 2003 Updated: September 18, 2003

Status

Affected

Vendor Statement

-----BEGIN PGP SIGNED MESSAGE-----

Sendmail, Inc., and the Sendmail Consortium announce the availability
of sendmail 8.12.10. It contains a fix for a security problem
discovered by Michal Zalewski whom we thank for bringing this problem
to our attention. We also want to thank Todd C. Miller for providing
a patch. sendmail 8.12.10 also includes fixes for other potential
problems, see the release notes below for more details. Sendmail
urges all users to either upgrade to sendmail 8.12.10 or apply a
patch which is part of this announcement. Remember to check the
PGP signatures of patches or releases obtained via FTP or HTTP (to
check the correctness of the patch in this announcement please
verify the PGP signature of it). For those not running the open
source version, check with your vendor for a patch.

For a complete list of changes see the release notes down below.

Please send bug reports to sendmail-bugs@sendmail.org as usual.
Please send security reports to sendmail-security@sendmail.org using
PGP encryption.

Note: We have changed the way we digitally sign the source code
distributions to simplify verification: in contrast to earlier
versions two .sig files are provided, one each for the gzip'ed
version and the compressed version. That is, instead of signing the
tar file, we sign the compressed/gzip'ed files, so you do not need
to uncompress the file before checking the signature.

This version can be found at

ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.12.10.tar.gz
ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.12.10.tar.gz.sig
ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.12.10.tar.Z
ftp://ftp.sendmail.org/pub/sendmail/sendmail.8.12.10.tar.Z.sig

and the usual mirror sites.

MD5 signatures:

393f5d09d462f522c8288363870b2b42 sendmail.8.12.10.tar.gz
345042839dec70f0a0b5aaeafcf3a0e3 sendmail.8.12.10.tar.gz.sig
36b2b74577a96f79c242ff036321c2ff sendmail.8.12.10.tar.Z
1b9cd61e1342207148d950feafab0f07 sendmail.8.12.10.tar.Z.sig

You either need the first two files or the third and fourth, i.e.,
the gzip'ed version or the compressed version and the corresponding
.sig file. The PGP signature was created using the Sendmail Signing
Key/2003, available on the web site (http://www.sendmail.org/) or
on the public key servers.

Since sendmail 8.11 and later includes hooks to cryptography, the
following information from OpenSSL applies to sendmail as well.

PLEASE REMEMBER THAT EXPORT/IMPORT AND/OR USE OF STRONG CRYPTOGRAPHY
SOFTWARE, PROVIDING CRYPTOGRAPHY HOOKS OR EVEN JUST COMMUNICATING
TECHNICAL DETAILS ABOUT CRYPTOGRAPHY SOFTWARE IS ILLEGAL IN SOME
PARTS OF THE WORLD. SO, WHEN YOU IMPORT THIS PACKAGE TO YOUR
COUNTRY, RE-DISTRIBUTE IT FROM THERE OR EVEN JUST EMAIL TECHNICAL
SUGGESTIONS OR EVEN SOURCE PATCHES TO THE AUTHOR OR OTHER PEOPLE
YOU ARE STRONGLY ADVISED TO PAY CLOSE ATTENTION TO ANY EXPORT/IMPORT
AND/OR USE LAWS WHICH APPLY TO YOU. THE AUTHORS ARE NOT LIABLE FOR
ANY VIOLATIONS YOU MAKE HERE. SO BE CAREFUL, IT IS YOUR RESPONSIBILITY.

SENDMAIL RELEASE NOTES
$I d : R E L E A S E_{N} O T E S, v 8.1340 .2 .165 2003 / 09 / 1620 : 50 : 42 c a E x p$

This listing shows the version of the sendmail binary, the version
of the sendmail configuration files, the date of release, and a
summary of the changes in that release.

8.12.10/8.12.102003/09/24
SECURITY: Fix a buffer overflow in address parsing. Problem
detected by Michal Zalewski, patch from Todd C. Miller
of Courtesan Consulting.
Fix a potential buffer overflow in ruleset parsing. This problem
is not exploitable in the default sendmail configuration;
only if non-standard rulesets recipient (2), final (4), or
mailer-specific envelope recipients rulesets are used then
a problem may occur. Problem noted by Timo Sirainen.
Accept 0 (and 0/0) as valid input for set MaxMimeHeaderLength.
Problem noted by Thomas Schulz.
Add several checks to avoid (theoretical) buffer over/underflows.
Properly count message size when performing 7->8 or 8->7 bit MIME
conversions. Problem noted by Werner Wiethege.
Properly compute message priority based on size of entire message,
not just header. Problem noted by Axel Holscher.
Reset SevenBitInput to its configured value between SMTP
transactions for broken clients which do not properly
announce 8 bit data. Problem noted by Stefan Roehrich.
Set {addr_type} during queue runs when processing recipients.
Based on patch from Arne Jansen.
Better error handling in case of (very unlikely) queue-id conflicts.
Perform better error recovery for address parsing, e.g., when
encountering a comment that is too long. Problem noted by
Tanel Kokk, Union Bank of Estonia.
Add ':' to the allowed character list for bogus HELO/EHLO
checking. It is used for IPv6 domain literals. Patch from
Iwaizako Takahiro of FreeBit Co., Ltd.
Reset SASL connection context after a failed authentication attempt.
Based on patch from Rob Siemborski of CMU.
Check Berkeley DB compile time version against run time version
to make sure they match.
Do not attempt AAAA (IPv6) DNS lookups if IPv6 is not enabled
in the kernel.
When a milter adds recipients and one of them causes an error,
do not ignore the other recipients. Problem noted by
Bart Duchesne.
CONFIG: Use specified SMTP error code in mailertable entries which
lack a DSN, i.e., "error:### Text". Problem noted by
Craig Hunt.
CONFIG: Call Local_trust_auth with the correct argument. Patch
from Jerome Borsboom.
CONTRIB: Better handling of temporary filenames for doublebounce.pl
and expn.pl to avoid file overwrites, etc. Patches from
Richard A. Nelson of Debian and Paul Szabo.
MAIL.LOCAL: Fix obscure race condition that could lead to an
improper mailbox truncation if close() fails after the
mailbox is fsync()'ed and a new message is delivered
after the close() and before the truncate().
MAIL.LOCAL: If mail delivery fails, do not leave behind a
stale lockfile (which is ignored after the lock timeout).
Patch from Oleg Bulyzhin of Cronyx Plus LLC.
Portability:
Port for AIX 5.2. Thanks to Steve Hubert of University
of Washington for providing access to a computer
with AIX 5.2.
setreuid(2) works on OpenBSD 3.3. Patch from
Todd C. Miller of Courtesan Consulting.
Allow for custom definition of SMRSH_CMDDIR and SMRSH_PATH
on all operating systems. Patch from Robert Harker
of Harker Systems.
Use strerror(3) on Linux. If this causes a problem on
your Linux distribution, compile with
-DHASSTRERROR=0 and tell sendmail.org about it.
Added Files:
devtools/OS/AIX.5.2

Instructions to extract and apply the patch for sendmail:

Store the data between "========= begin patch ========" and "=========
end patch ==========" into a file called "/PATH/TO/patch.sm" (replace
"/PATH/TO" with a path of your choice) and apply the following
command in the sendmail-VERSION/sendmail/ directory (note: if you
have a really old version then cd to sendmail-VERSION/src/)

patch < /PATH/TO/patch.sm

You should also edit the file version.c and change the version
number to indicate that you changed sendmail. We suggest to add the
date, e.g., change "8.12.9" to "8.12.9-20030924". Then recompile
sendmail, install the new binary, and restart the daemon.

========= begin patch ========

diff -u -r8.359.2.8 parseaddr.c
- --- parseaddr.c3 Apr 2003 16:20:54 -00008.359.2.8
+++ parseaddr.c16 Sep 2003 18:06:22 -0000
@@ -700,7 +700,11 @@
addr[MAXNAME] = '\0';
returnnull:
if (delimptr != NULL)
+{
+if (p > addr)
+--p;
*delimptr = p;
+}
CurEnv->e_to = saveto;
return NULL;
}
========= end patch ==========
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Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

The CERT/CC has no additional comments at this time.

If you have feedback, comments, or additional information about this vulnerability, please send us email.

TurboLinux Affected

Wirex Affected

F5 Networks Not Affected

Lotus Software Not Affected

Network Appliance Not Affected

Openwall GNU/*/Linux Not Affected

Syntegra Not Affected

3Com Unknown

AT&T Unknown

Alcatel Unknown

Avaya Unknown

Cisco Systems Inc. Unknown

Computer Associates Unknown

Cray Inc. Unknown

D-Link Systems Unknown

Data General Unknown

Extreme Networks Unknown

Foundry Networks Inc. Unknown

Fujitsu Unknown

Guardian Digital Inc. Unknown

Hitachi Unknown

Ingrian Networks Unknown

Intel Unknown

Juniper Networks Unknown

Lucent Technologies Unknown

Microsoft Corporation Unknown

MontaVista Software Unknown

Multi-Tech Systems Inc. Unknown

Multinet Unknown

NEC Corporation Unknown

NetScreen Unknown

Nokia Unknown

Nortel Networks Unknown

OpenBSD Unknown

Oracle Corporation Unknown

Redback Networks Inc. Unknown

Riverstone Networks Unknown

SCO Unknown

Sequent Unknown

Sony Corporation Unknown

Unisys Unknown

Wind River Systems Inc. Unknown

Xerox Unknown

ZyXEL Unknown

View all 63 vendors View less vendors

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

Acknowledgements

This vulnerability was discovered by Michal Zalewski.

This document was written by Art Manion.

Other Information

CVE IDs:	CVE-2003-0694
CERT Advisory:	CA-2003-25
Severity Metric:	36.72
Date Public:	2003-09-17
Date First Published:	2003-09-17
Date Last Updated:	2003-09-29 22:39 UTC
Document Revision:	20

Software Engineering Institute

CERT Coordination Center

Sendmail prescan() buffer overflow vulnerability

Vulnerability Note VU#784980

Overview

Description

Impact

Solution

Vendor Information

Apple Computer Inc. Affected

Conectiva Affected

Debian Affected

FreeBSD Affected

Gentoo Linux Affected

Hewlett-Packard Company Affected

IBM Affected

IBM eServer Affected

MandrakeSoft Affected

NETBsd Affected

OpenPKG Affected

Red Hat Inc. Affected

SGI Affected

Secure Computing Corporation Affected

Sendmail Inc. Affected

Slackware Affected

SuSE Inc. Affected

Sun Microsystems Inc. Affected

The Sendmail Consortium Affected

TurboLinux Affected

Wirex Affected

F5 Networks Not Affected

Lotus Software Not Affected

Network Appliance Not Affected

Openwall GNU/*/Linux Not Affected

Syntegra Not Affected

3Com Unknown

AT&T Unknown

Alcatel Unknown