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AUSCERT External Security Bulletin Redistribution
ESB-2003.0671 -- Sun(sm) Alert Notification
Sun Alert ID: 56860 - sendmail(1M) Buffer Overflow Vulnerability in
Address Parsing Function prescan( )
22 September 2003
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AusCERT Security Bulletin Summary
---------------------------------
Product: sendmail
Publisher: Sun Microsystems
Operating System: Solaris 9
Solaris 8
Solaris 7
Platform: SPARC
x86
Impact: Root Compromise
Denial of Service
Access Required: Remote
Ref: AL-2003.17
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DOCUMENT ID: 56860
SYNOPSIS: sendmail(1M) Buffer Overflow Vulnerability in Address
Parsing Function prescan( )
DETAIL DESCRIPTION:
Sun(sm) Alert Notification
* Sun Alert ID: 56860
* Synopsis: sendmail(1M) Buffer Overflow Vulnerability in Address
Parsing Function prescan()
* Category: Security
* Product: Solaris
* BugIDs: 4924036
* Avoidance: Workaround
* State: Committed
* Date Released: 19-Sep-2003
* Date Closed:
* Date Modified:
1. Impact
A local or remote unprivileged user may be able to gain unauthorized
root access or cause a denial of service due to a buffer overflow in
the sendmail(1M) daemon within the prescan() function.
This issue is described in CERT Vulnerability VU#784980 (see
[1]http://www.kb.cert.org/vuls/id/784980) which is referenced in CERT
Advisory CA-2003-25 (see
[2]http://www.cert.org/advisories/CA-2003-25.html).
2. Contributing Factors
This issue can occur in the following releases:
SPARC Platform
* Solaris 7
* Solaris 8
* Solaris 9
x86 Platform
* Solaris 7
* Solaris 8
* Solaris 9
By default, all systems are potentially vulnerable to this issue.
Systems are vulnerable if they have a sendmail daemon running. This
can be confirmed by the following commands:
1) To determine if a sendmail process is running on the system, do the
following:
$ /usr/bin/ps -e | grep sendmail
20038 ? 0:03 sendmail
2) If there is a sendmail process present, the following command will
confirm if the process is the sendmail daemon:
$ /usr/bin/mconnect
connecting to host localhost (127.0.0.1), port 25
connection open
220 an.example.com ESMTP Sendmail 8.12.8+Sun/8.12.8; Wed, 5 Mar 2003
17:47:49 -0700 (MST)
help
214-2.0.0 This is sendmail version 8.12.8+Sun
214-2.0.0 Topics:
214-2.0.0 HELO EHLO MAIL RCPT DATA
214-2.0.0 RSET NOOP QUIT HELP VRFY
214-2.0.0 EXPN VERB ETRN DSN
214-2.0.0 For more info use "HELP <topic>".
214-2.0.0 To report bugs in the implementation contact Sun
Microsystems
214-2.0.0 Technical Support.
214-2.0.0 For local information send email to Postmaster at your site.
214 2.0.0 End of HELP info
quit
221 2.0.0 an.example.com closing connection
Note: On sendmail version 8.12.x (available in Solaris 9) the file,
"/etc/mail/helpfile", may have been modified by the system
administrator which could obscure the version number.
3) If the sendmail daemon is not running (and therefore not available)
the output from mconnect(1) would be:
$ /usr/bin/mconnect
connecting to host localhost (127.0.0.1), port 25
connect: Connection refused
3. Symptoms
There are no reliable symptoms that would show the described issue has
been exploited to gain unauthorized root access to a host.
SOLUTION SUMMARY:
4. Relief/Workaround
Until patches can be applied, sites may wish to block access to the
affected service from untrusted networks such as the Internet or
disable the daemon where possible. Use a firewall or other
packet-filtering technology to block the appropriate network ports.
Consult your vendor or your firewall documentation for detailed
instructions on how to configure the ports.
To disable sendmail(1M) the following commands can be executed as
root:
# /etc/init.d/sendmail stop
# mv /etc/rc2.d/S88sendmail /etc/rc2.d/not-S88sendmail
This will prevent e-mail messages from being received on the system
until sendmail(1M) is started again and re-enabled with the commands:
# /etc/init.d/sendmail start
# mv /etc/rc2.d/not-S88sendmail /etc/rc2.d/S88sendmail
5. Resolution
A final resolution is pending completion.
This Sun Alert notification is being provided to you on an "AS IS"
basis. This Sun Alert notification may contain information provided by
third parties. The issues described in this Sun Alert notification may
or may not impact your system(s). Sun makes no representations,
warranties, or guarantees as to the information contained herein. ANY
AND ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR
NON-INFRINGEMENT, ARE HEREBY DISCLAIMED. BY ACCESSING THIS DOCUMENT
YOU ACKNOWLEDGE THAT SUN SHALL IN NO EVENT BE LIABLE FOR ANY DIRECT,
INDIRECT, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES THAT ARISE
OUT OF YOUR USE OR FAILURE TO USE THE INFORMATION CONTAINED HEREIN.
This Sun Alert notification contains Sun proprietary and confidential
information. It is being provided to you pursuant to the provisions of
your agreement to purchase services from Sun, or, if you do not have
such an agreement, the Sun.com Terms of Use. This Sun Alert
notification may only be used for the purposes contemplated by these
agreements.
Copyright 2000-2003 Sun Microsystems, Inc., 4150 Network Circle, Santa
Clara, CA 95054 U.S.A. All rights reserved.
References
1. http://www.kb.cert.org/vuls/id/784980
2. http://www.cert.org/advisories/CA-2003-25.html
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