Az ISS egy puffer túlcsordulási hibát fedezett fel a sendmailben, amely akkor lép fel amikor a sendmail a headereket ellenőrzi. A hiba a sendmail összes verziójában jelen van az 5.79-es verziótól kezdve. A FreeBSD csapat is számos lépést tett a hiba elhárítására.
Bejelentés, patchek:From: FreeBSD Security Advisories
To: FreeBSD Security Advisories
Date: Mon, March 3, 2003 10:11 am
Subject: FreeBSD Security Advisory FreeBSD-SA-03:04.sendmail
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FreeBSD-SA-03:04.sendmail Security Advisory
The FreeBSD Project
Topic: sendmail header parsing buffer overflow
Category: contrib
Module: contrib_sendmail
Announced: 2003-03-03
Credits: Mark Dowd (ISS)
Affects: All releases prior to 4.8-RELEASE and 5.0-RELEASE-p4
FreeBSD 4-STABLE prior to the correction date
Corrected: 2003-03-03
FreeBSD only: NO
I. Background
FreeBSD includes sendmail(8), a general purpose internetwork mail routing facility, as the default Mail Transfer Agent (MTA).
II. Problem Description
ISS has identified a buffer overflow that may occur during header parsing in all versions of sendmail after version 5.79.
In addition, Sendmail, Inc. has identified and corrected a defect in buffer handling within sendmail's RFC 1413 ident protocol support.
III. Impact
A remote attacker could create a specially crafted message that may cause sendmail to execute arbitrary code with the privileges of the user running sendmail, typically root. The malicious message might be handled (and therefore the vulnerability triggered) by the initial sendmail MTA, any relaying sendmail MTA, or by the delivering sendmail process. Exploiting this defect is particularly difficult, but is believed to be possible.
The defect in the ident routines is not believed to be exploitable.
IV. Workaround
There is no workaround, other than disabling sendmail.
V. Solution
Do one of the following:
1) Upgrade your vulnerable system to 4-STABLE; or to the RELENG_5_0,
RELENG_4_7, or RELENG_4_6 security branch dated after the correction
date (5.0-RELEASE-p4, 4.7-RELEASE-p7, or 4.6.2-RELEASE-p10,
respectively).
[NOTE: At the time of this writing, the FreeBSD 4-STABLE branch is labeled `4.8-RC1'.]
2) To patch your present system:
The following patch has been verified to apply to FreeBSD 5.0, 4.7, and 4.6 systems.
a) Download the relevant patch from the location below, and verify the detached PGP signature using your PGP utility.
ftp://ftp.FreeBSD.org/pub/FreeBSD/C.../sendmail.patch
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...dmail.patch.asc
b) Execute the following commands as root:
# cd /usr/src
# patch
# cd /usr/src/lib/libsm
# make obj && make depend && make
# cd /usr/src/lib/libsmutil
# make obj && make depend && make
# cd /usr/src/usr.sbin/sendmail
# make obj && make depend && make && make install
3) For i386 systems only, a patched sendmail binary is available.
Select the correct binary based on your FreeBSD version and whether or not you want STARTTLS support. If you want STARTTLS support, you must have the crypto distribution installed.
a) Download the relevant binary from the location below, and verify the detached PGP signature using your PGP utility.
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...6-crypto.bin.gz
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...ypto.bin.gz.asc
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...nocrypto.bin.gz
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...ypto.bin.gz.asc
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...6-crypto.bin.gz
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...ypto.bin.gz.asc
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...nocrypto.bin.gz
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...ypto.bin.gz.asc
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...6-crypto.bin.gz
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...ypto.bin.gz.asc
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...nocrypto.bin.gz
ftp://ftp.FreeBSD.org/pub/FreeBSD/C...ypto.bin.gz.asc
b) Install the binary. Execute the following commands as root. Note that these examples utilizes the FreeBSD 4.7 crypto binary. Substitute BINARYGZ with the file name which you downloaded in step (a).
# BINARYGZ=/path/to/sendmail-4.7-i386-crypto.bin.gz
# gunzip ${BINARYGZ}
# install -s -o root -g smmsp -m 2555 ${BINARYGZ%.gz} /usr/libexec/sendmail/sendmail
c) Restart sendmail. Execute the following command as root.
# /bin/sh /etc/rc.sendmail restart
VI. Correction details
The following list contains the revision numbers of each file that was corrected in FreeBSD.
Path Revision
Branch
- -------------------------------------------------------------------------
src/contrib/src/sendmail.h
src/contrib/sendmail/src/daemon.c
src/contrib/sendmail/src/headers.c
src/contrib/sendmail/src/main.c
src/contrib/sendmail/src/parseaddr.c
- -------------------------------------------------------------------------
VII. References
URL: http://www.kb.cert.org/vuls/id/398025
URL: http://www.iss.net/issEn/delivery/x...l.jsp?oid=21950
URL: http://www.cve.mitre.org/cgi-bin/cv...e=CAN-2002-1337
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