CERT/CC Vulnerability Note VU#398025

Overview

There is a vulnerability in sendmail that may allow remote attackers to gain the privileges of the sendmail daemon, typically root.

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.

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.

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 this document.

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.

Vendor Information

398025

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Apple Computer Inc. Affected

BSD/OS Affected

Conectiva Affected

Debian Affected

FreeBSD Affected

Gentoo Linux Affected

Hewlett-Packard Company Affected

Notified: January 27, 2003 Updated: September 15, 2003

Status

Affected

Vendor Statement

SOURCE: Hewlett-Packard Company HP Services Software Security Response Team

x-ref: SSRT3469
HP released security bulletins for this issue on 03 March 2003 and recently updated 11 March 2003 for Internet Express and AVFW98.
View at www.hp.com and in the search window type SSRT3469
For HP-UX use your normal ITRC access and select Security Bulletin HPSBUX0302-246

This problem affects supported versions of HP-UX, HP Tru64 UNIX/TruCluster Server, HP AlphaServer SC (Sierra Cluster) V2.5, HP Internet Express, HP AltaVista Firewall (AVFW98 / Raptor EC).

NOTE: This problem does not impact HP NonStop Servers nor HP OpenVMS.

Vendor Information

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

Addendum

The following is an archived copy of the Hewlett-Packard Security Bulletin regarding this vulnerability:

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
----------------------------------------------------------------- **REVISED 05**
Source: HEWLETT-PACKARD COMPANY SECURITY BULLETIN: HPSBUX0302-246 Originally issued: 03 March 2003 Last revised: 18 August 2003 SSRT3469 Potential Security Vulnerability in sendmail (rev.5) -----------------------------------------------------------------

NOTICE: There are no restrictions for distribution of this Bulletin provided that it remains complete and intact.
The information in the following Security Bulletin should be acted upon as soon as possible. Hewlett-Packard Company will not be liable for any consequences to any customer resulting from customer's failure to fully implement instructions in this Security Bulletin as soon as possible.
----------------------------------------------------------------- PROBLEM: Potential security vulnerability in sendmail
IMPACT: Potential unauthorized Privileged Access, Potential Denial of Service (DoS).

PLATFORM: HP 9000 Series 700/800 Servers running HP-UX B.10.10, B.10.20, B.11.00, B.11.04(VVOS), B.11.11, and B.11.22.

**REVISED 05** SOLUTION: B.10.10 - write to security-alert@hp.com for information
--> B.10.20 - install PHNE_28760 --> B.11.00 (sendmail-8.9.3) - install PHNE_28809 --> B.11.00 (sendmail-8.11.1) - install web upgrade --> B.11.04 - install PHNE_29526 --> B.11.11 (sendmail-8.9.3) - install PHNE_28810 --> B.11.11 (sendmail-8.11.1) - install web upgrade --> B.11.22 - install PHNE_28409

MANUAL ACTIONS: Yes - NonUpdate B.10.10: write to security-alert@hp.com for information All versions: Modify /etc/mail/sendmail.cf

AVAILABILITY: Fixes are available for B.10.10, B.10.20, B.11.00, B.11.04(VVOS), B.11.11, and B.11.22.

CHANGE SUMMARY: Rev.01 - Added information on upgrading from 8.8.6 to 8.9.3 or 8.11.1. Added information on warning messages. Added CERT and CVE reference numbers.
Rev.02 - Corrected typo. Added 11.04(VVOS) information. Added 8.7.x to list of affected versions.
Rev.03 - Added HPSecurityBul246.depot information. Replaced sendmail.811.11.11 file with sendmail.811.11.11.r1. Renamed sendmail.886.10.01 to
sendmail.886.10.10. Clarified installation instructions.
Rev.04 - Added note about HPSBUX0304-253. The files are in the SB246 subdirectory on the ftp site.
Rev.05 - patches and web upgrades available. ----------------------------------------------------------------- A. Background
A potential security vulnerability with sendmail has been reported in HP-UX. This potential vulnerability may result in unauthorized Privileged Access or a Denial of Service (DoS). This potential vulnerability may be exploited remotely.

This is the vulnerability reported in CERT/CC CA-2003-07. CERT/CC is tracking this issue as VU#398025 This reference number corresponds to CVE candidate CAN-2002-1337.

This problem also affects HP Tru64 UNIX/Trucluster Server. NOTE: This problem does not impact HP NonStop Servers nor
HP OpenVMS. The HP Tru64 bulletin will be posted to the customer support website within 24 hours of release to - http://thenew.hp.com/country/us/eng/support.html or www.hp.com Use the SEARCH IN feature box, enter SSRT in the search window or use a specific SSRT # example: SSRT3469

HP ProLiant Servers If running Open Source Sendmail, refer to the following Sendmail Consortium URL for patch details or upgrades: http://www.sendmail.org As more information becomes available HP will provide notice of the availability of any necessary patches through standard security bulletin announcements and be available from your normal HP Services support channel.

NOT VULNERABLE: HP NonStop Servers HP OpenVMS.

AFFECTED VERSIONS
The following is a list by HP-UX revision of affected filesets and the fileset revision or patch containing the fix. To determine if a system has an affected version, search the output of "swlist -a revision -l fileset" for an affected fileset, then determine if a fixed revision or the applicable patch is installed.

HP-UX B.11.22 ============= InternetSrvcs.INETSVCS2-RUN InternetSrvcs.INETSVCS-RUN fix: PHNE_28409 or subsequent
Modify /etc/mail/sendmail.cf
**REVISED 05** HP-UX B.11.11 ============= SMAIL-811.INETSVCS-SMAIL
--> fix: B.11.11.01.005 or subsequent --> (web upgrade to Sendmail 8.11.1 Version 5 --> or subsequent)
Modify /etc/mail/sendmail.cf
InternetSrvcs.INETSVCS-RUN fix: PHNE_28810 or subsequent
Modify /etc/mail/sendmail.cf
HP-UX B.11.04 ============= InternetSrvcs.INETSVCS-RUN
--> fix: PHNE_29526 or subsequent
HP-UX B.11.00 ============= SMAIL-811.INETSVCS-SMAIL
--> fix: B.11.00.01.004 or subsequent --> (web upgrade to Sendmail 8.11.1 Version 4 --> or subsequent)
Modify /etc/mail/sendmail.cf
InternetSrvcs.INETSVCS-RUN fix: PHNE_28809 or subsequent
Modify /etc/mail/sendmail.cf
HP-UX B.10.20 ============= InternetSrvcs.INETSVCS-RUN fix: PHNE_28760 or subsequent
Modify /etc/mail/sendmail.cf
**REVISED 05** HP-UX B.10.10 ============= InternetSrvcs.INETSVCS-RUN
--> fix: write to security-alert@hp.com for information
END AFFECTED VERSIONS
B. Recommended solution
Modify /etc/mail/sendmail.cf as follows:
Add "restrictqrun" to the PrivacyOptions. After the change the line should read:

O PrivacyOptions=authwarnings,restrictqrun
Then install the patch or upgrade.

Determine the sendmail version:
Login in as root: cd /usr/sbin sendmail -d0.1 < /dev/null | grep -i version

The display will show Version #.#.#
Install the fix for that version as described below.
HP-UX B.11.22 sendmail 8.11.1 PHNE_28409 is now available.

**REVISED 05** HP-UX B.11.00 and B.11.11 sendmail 8.11.1
--> A web upgrade is available from software.hp.com: <http://www.software.hp.com/cgi-bin/swdepot_parser.cgi/ cgi/displayProductInfo.pl?productNumber=SMAIL811>

HP-UX B.11.11 sendmail 8.9.3 PHNE_28810 is now available.

-->HP-UX B.11.04 sendmail 8.9.3 --> PHNE_29526 is now available.

HP-UX B.11.00 sendmail 8.9.3 PHNE_28809 is now available.

HP-UX B.10.20 sendmail 8.9.3 PHNE_28760 is now available.

-->For B.10.10 write to security-alert@hp.com for information.
Note: If you receive either of the following messages after applying the fix, please follow the recommended action.

warning: /etc/mail/aliases has world read or write permission. This is unsafe.

warning: /etc/mail/aliases.db has world read or write permission. This is unsafe.

Recommended action
Execute the following commands.
chmod 640 /etc/mail/aliases chmod 640 /etc/mail/aliases.db sendmail -bi

C. To subscribe to automatically receive future NEW HP Security Bulletins from the HP IT Resource Center via electronic mail, do the following:

Use your browser to get to the HP IT Resource Center page at:

http://itrc.hp.com
Use the 'Login' tab at the left side of the screen to login using your ID and password. Use your existing login or the "Register" button at the left to create a login, in order to gain access to many areas of the ITRC. Remember to save the User ID assigned to you, and your password.

In the left most frame select "Maintenance and Support".
Under the "Notifications" section (near the bottom of the page), select "Support Information Digests".

To -subscribe- to future HP Security Bulletins or other Technical Digests, click the check box (in the left column) for the appropriate digest and then click the "Update Subscriptions" button at the bottom of the page.

or
To -review- bulletins already released, select the link (in the middle column) for the appropriate digest.

NOTE: Using your itrc account security bulletins can be found here:
http://itrc.hp.com/cki/bin/doc.pl/screen=ckiSecurityBulletin

To -gain access- to the Security Patch Matrix, select the link for "The Security Bulletins Archive". (near the bottom of the page) Once in the archive the third link is to the current Security Patch Matrix. Updated daily, this matrix categorizes security patches by platform/OS release, and by bulletin topic. Security Patch Check completely automates the process of reviewing the patch matrix for 11.XX systems.

For information on the Security Patch Check tool, see: http://www.software.hp.com/cgi-bin/swdepot_parser.cgi/cgi/ displayProductInfo.pl?productNumber=B6834AA

The security patch matrix is also available via anonymous ftp:

ftp://ftp.itrc.hp.com/export/patches/hp-ux_patch_matrix/
On the "Support Information Digest Main" page: click on the "HP Security Bulletin Archive".

The PGP key used to sign this bulletin is available from several PGP Public Key servers. The key identification information is:

2D2A7D59 HP Security Response Team (Security Bulletin signing only) <security-alert@hp.com> Fingerprint =
6002 6019 BFC1 BC62 F079 862E E01F 3AFC 2D2A 7D59
If you have problems locating the key please write to security-alert@hp.com. Please note that this key is for signing bulletins only and is not the key returned by sending 'get key' to security-alert@hp.com.

D. To report new security vulnerabilities, send email to
security-alert@hp.com
Please encrypt any exploit information using the security-alert PGP key, available from your local key server, or by sending a message with a -subject- (not body) of 'get key' (no quotes) to security-alert@hp.com.

-----------------------------------------------------------------
(c)Copyright 2003 Hewlett-Packard Company Hewlett-Packard Company shall not be liable for technical or editorial errors or omissions contained herein. The information in this document is subject to change without notice. Hewlett-Packard Company and the names of HP products referenced herein are trademarks and/or service marks of Hewlett-Packard Company. Other product and company names mentioned herein may be trademarks and/or service marks of their respective owners.
_________________________________________________________________
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If you have feedback, comments, or additional information about this vulnerability, please send us email.

IBM Affected

MandrakeSoft Affected

NetBSD Affected

Nortel Networks Affected

OpenBSD Affected

OpenPKG Affected

Red Hat Inc. Affected

SGI Affected

Sendmail Inc. Affected

Slackware Affected

SuSE Inc. Affected

Sun Microsystems Inc. Affected

The SCO Group (SCO Linux) Affected

The SCO Group (SCO UnixWare) Affected

The Sendmail Consortium Affected

Xerox Corporation Affected

Hitachi Not Affected

Juniper Networks Not Affected

Lotus Software Not Affected

Openwall GNU/*/Linux Not Affected

Syntegra Not Affected

AT&T Unknown

Alcatel Unknown

Avaya Unknown

Check Point Unknown

Cisco Systems Inc. Unknown

Computer Associates Unknown

Cray Inc. Unknown

Fujitsu Unknown

Guardian Digital Inc. Unknown

IBM-zSeries Unknown

Lucent Technologies Unknown

NEC Corporation Unknown

Nokia Unknown

Novell Unknown

Secure Computing Corporation Unknown

Sequent Unknown

Sony Corporation Unknown

Symantec Corporation Unknown

View all 46 vendors View less vendors

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

Acknowledgements

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.

This document was written by Jeffrey P. Lanza and Shawn V. Hernan.

Other Information

CVE IDs:	CVE-2002-1337
CERT Advisory:	CA-2003-07
Severity Metric:	66.00
Date Public:	2003-03-03
Date First Published:	2003-03-03
Date Last Updated:	2003-09-15 13:59 UTC
Document Revision:	24

Software Engineering Institute

CERT Coordination Center

Remote Buffer Overflow in Sendmail

Vulnerability Note VU#398025

Overview

Description

Impact

Solution

Vendor Information

Apple Computer Inc. Affected

BSD/OS Affected

Conectiva Affected

Debian Affected

FreeBSD Affected

Gentoo Linux Affected

Hewlett-Packard Company Affected

IBM Affected

MandrakeSoft Affected

NetBSD Affected

Nortel Networks Affected

OpenBSD Affected

OpenPKG Affected

Red Hat Inc. Affected

SGI Affected

Sendmail Inc. Affected

Slackware Affected

SuSE Inc. Affected

Sun Microsystems Inc. Affected

The SCO Group (SCO Linux) Affected

The SCO Group (SCO UnixWare) Affected

The Sendmail Consortium Affected

Xerox Corporation Affected

Hitachi Not Affected

Juniper Networks Not Affected

Lotus Software Not Affected

Openwall GNU/*/Linux Not Affected

Syntegra Not Affected

AT&T Unknown