__________________________________________________________
The U.S. Department of Energy
Computer Incident Advisory Capability
___ __ __ _ ___
/ | /_\ /
\___ __|__ / \ \___
__________________________________________________________
INFORMATION BULLETIN
Vulnerability in IMAP and POP
March 27, 1998 17:00 GMT Number H-46a
______________________________________________________________________________
PROBLEM: A vulnerability has been reported in some versions of the
Internet Message Access Protocol (IMAP) and Post Office
Protocol (POP) implementations (imapd, ipop2d, and ipop3d).
PLATFORM: See "Appendix A - Vendor Information" below for platforms
effected.
DAMAGE: By exploiting this vulnerability, may allow remote users can
obtain unauthorized root access.
SOLUTION: Implement the following: 1) Obtain and install patch from your
vendor, 2) Upgrade to the latest version of IMAP, or 3) Disable
services.
______________________________________________________________________________
VULNERABILITY Information about this vulnerability has been publicly
ASSESSMENT: distributed.
______________________________________________________________________________
[ Appended on March 27, 1998 with additional vendor information from
Silicon Graphics Inc. ]
[Start of CERT Advisory]
=============================================================================
CERT* Advisory CA-97.09
Original issue date: April 7, 1997
Last revised: April 9, 1997
Appendix A - added vendor information for Digital Equipment
Corporation and QUALCOMM Incorporated.
Updated vendor information for Sun Microsystems, Inc.
Added another name to acknowledgment.
Topic: Vulnerability in IMAP and POP
------------------------------------------------------------------------------
The CERT Coordination Center has received reports of a vulnerability
in some versions of the Internet Message Access Protocol (IMAP) and
Post Office Protocol (POP) implementations (imapd, ipop2d, and
ipop3d). Information about this vulnerability has been publicly
distributed.
By exploiting this vulnerability, remote users can obtain unauthorized root
access.
The CERT/CC team recommends installing a patch if one is available or
upgrading to IMAP4rev1. Until you can do so, we recommend disabling the IMAP
and POP services at your site.
We will update this advisory as we receive additional information.
Please check our advisory files regularly for updates that relate to
your site.
------------------------------------------------------------------------------
I. Description
The current version of Internet Message Access Protocol (IMAP) supports
both online and offline operation, permitting manipulation of remote
message folders. It provides access to multiple mailboxes (possibly on
multiple servers), and supports nested mailboxes as well as
resynchronization with the server. The current version also provides a
user with the ability to create, delete, and rename mailboxes. Additional
details concerning the functionality of IMAP can be found in RFC 2060
(the IMAP4rev1 specification) available from
http://ds.internic.net/rfc/rfc2060.txt
The Post Office Protocol (POP) was designed to support offline mail
processing. That is, the client connects to the server to download mail
that the server is holding for the client. The mail is deleted from the
server and is handled offline (locally) on the client machine.
In both protocols, the server must run with root privileges so it can
access mail folders and undertake some file manipulation on behalf of the
user logging in. After login, these privileges are discarded. However, a
vulnerability exists in the way the login transaction is handled, and
this can be exploited to gain privileged access on the server. By
preparing carefully crafted text to a system running a vulnerable version
of these servers, remote users may be able to cause a buffer overflow and
execute arbitrary instructions with root privileges.
Information about this vulnerability has been widely distributed.
II. Impact
Remote users can obtain root access on systems running a vulnerable IMAP
or POP server. They do not need access to an account on the system to do
this.
III. Solution
Install a patch from your vendor (see Section A) or upgrade to the latest
version of IMAP (Section B). If your POP server is based on the
University of Washington IMAP server code, you should also upgrade to
the latest version of IMAP. Until you can take one of these actions, you
should disable services (Section C). In all cases, we urge you to take
the additional precaution described in Section D.
A. Obtain and install a patch from your vendor
Below is a list of vendors who have provided information about this
vulnerability. Details are in Appendix A of this advisory; we will update
the appendix as we receive more information. If your vendor's name is not
on this list, please contact your vendor directly.
Berkeley Software Design, Inc. (BSDI)
Carnegie Mellon University
Cray Research
Digital Equipment Corporation
Linux - Red Hat
Caldera, Inc.
Sun Microsystems, Inc.
University of Washington
B. Upgrade to the latest version of IMAP
An alternative to installing vendor patches is upgrading to IMAP4rev1,
which is available from
ftp://ftp.cac.washington.edu/mail/imap.tar.Z
MD5 (imap.tar.Z) = 87329f3f87909fe29d5d0b1b10f22ee9
C. Disable services
Until you can take one of the above actions, temporarily disable the POP
and IMAP services. On many systems, you will need to edit the
/etc/inetd.conf file. However, you should check your vendor's
documentation because systems vary in file location and the exact
changes required (for example, sending the inetd process a HUP signal or
killing and restarting the daemon).
If you are not able to temporarily disable the POP and IMAP services,
then you should at least limit access to the vulnerable services to
machines in your local network. This can be done by installing the
tcp_wrappers described in Section D, not only for logging but also for
access control. Note that even with access control via tcp_wrappers, you
are still vulnerable to attacks from hosts that are allowed to connect
to the vulnerable POP or IMAP service.
D. Additional precaution
Because IMAP or POP is launched out of inetd.conf, tcp_wrappers can be
installed to log connections which can then be examined for suspicious
activity. You may want to consider filtering connections at the firewall
to discard unwanted/unauthorized connections.
The tcp_wrappers tool is available in
ftp://info.cert.org/pub/tools/tcp_wrappers/tcp_wrappers_7.5.tar.gz
MD5 (tcp_wrappers_7.5.tar.gz) = 8c7a17a12d9be746e0488f7f6bfa4abb
Note that this precaution does not address the vulnerability described
in this advisory, but it is a good security practice in general.
-----------------------------------------------------------------------------
Appendix A - Vendor Information
Below is a list of the vendors who have provided information for this
advisory. We will update this appendix as we receive additional information.
If you do not see your vendor's name, the CERT/CC did not hear from that
vendor. Please contact the vendor directly.
Berkeley Software Design, Inc. (BSDI)
=====================================
We're working on patches for both BSD/OS 2.1 and BSD/OS 3.0 for
imap (which we include as part of pine).
Carnegie Mellon University
==========================
Cyrus Server 1.5.2, with full IMAP4rev1 and pop3 capabilities, is NOT
affected by this report and is NOT vulnerable.
Cray Research
=============
Not vulnerable.
Digital Equipment Corporation
=============================
This reported problem is not present for Digital's UNIX or
Digital ULTRIX Operating Systems Software.
Linux Systems
=============
Caldera, Inc.
-------------
On systems such as Caldera OpenLinux 1.0, an unprivileged user can
obtain root access.
As a temporary workaround, you can disable the POP and IMAP services
in /etc/inetd.conf, and then kill and restart inetd.
A better solution is to install the new RPM package that contains
the fixed versions of the IMAP and POP daemons. They are located
on Caldera's FTP server (ftp.caldera.com):
/pub/openlinux/updates/1.0/006/RPMS/imap-4.1.BETA-1.i386.rpm
The MD5 checksum (from the "md5sum" command) for this package is:
45a758dfd30f6d0291325894f9ec4c18
This and other Caldera security resources are located at:
http://www.caldera.com/tech-ref/security/
Red Hat
-------
The IMAP servers included with all versions of Red Hat Linux have
a buffer overrun which allow *remote* users to gain root access on
systems which run them. A fix for Red Hat 4.1 is now available
(details on it at the end of this note).
Users of Red Hat 4.0 should apply the Red Hat 4.1 fix. Users of previous
releases of Red Hat Linux are strongly encouraged to upgrade or simply
not run imap. You can remove imap from any machine running with Red
Hat Linux 2.0 or later by running the command "rpm -e imap", rendering
them immune to this problem.
All of the new packages are PGP signed with Red Hat's PGP key,
and may be obtained from ftp.redhat.com:/updates/4.1. If
you have direct Internet access, you may upgrade these packages on your
system with the following commands:
Intel:
rpm -Uvh ftp://ftp.redhat.com/updates/4.1/i386/imap-4.1.BETA-3.i386.rpm
MD5 (imap-4.1.BETA-3.i386.rpm) = 8ac64fff475ee43d409fc9776a6637a6
Alpha:
rpm -Uvh ftp://ftp.redhat.com/updates/4.1/alpha/imap-4.1.BETA-3.alpha.rpm
MD5 (imap-4.1.BETA-3.alpha.rpm) = fd42ac24d7c4367ee51fd00e631cae5b
SPARC:
rpm -Uvh ftp://ftp.redhat.com/updates/4.1/sparc/imap-4.1.BETA-3.sparc.rpm
MD5 (imap-4.1.BETA-3.sparc.rpm) = 751598aae3d179284b8ea4d7a9b78868
QUALCOMM Incorporated
======================
Our engineers have examined the QPopper source code, which is based
on source from UC Berkeley. They determined that QPopper is *NOT*
vulnerable to a buffer overflow attack as described in CA-97.09.
It strictly checks the size of messages before copying them into its
buffer.
Sun Microsystems, Inc.
======================
Not vulnerable.
University of Washington
========================
This vulnerability has been detected in the University of Washington c-client
library used in the UW IMAP and POP servers. This vulnerability affects all
versions of imapd prior to v10.165, all versions of ipop2d prior to 2.3(32),
and all versions of ipop3d prior to 3.3(27).
It is recommended that all sites using these servers upgrade to the
latest versions, available in the UW IMAP toolkit:
ftp://ftp.cac.washington.edu/mail/imap.tar.Z
MD5 (imap.tar.Z) = fb94453e8d2ada303e2db8d83d54bfb6
This is a source distribution which includes imapd, ipop2d, ipop3d. and
the c-client library. The IMAP server in this distribution conforms with
RFC2060 (the IMAP4rev1 specification).
Sites which are not yet prepared to upgrade from IMAP2bis to IMAP4
service may obtain a corrected IMAP2bis server as part of the latest
(3.96) UW Pine distribution, available at:
ftp://ftp.cac.washington.edu/pine/pine.tar.Z
MD5 (pine.tar.Z) = 37138f0d1ec3175cf1ffe6c062c9abbf
------------------------------------------------------------------------------
The CERT Coordination Center thanks the University of Washington's
Computing and Communications staff for information relating to this
advisory. We also thank Wolfgang Ley of DFN-CERT for his input. We
thank Matthew Wall of Carnegie Mellon University for additional
insightful feedback.
------------------------------------------------------------------------------
[End of CERT Advisory]
[ Appended by Silicon Graphic Inc. ]
-----BEGIN PGP SIGNED MESSAGE-----
______________________________________________________________________________
Silicon Graphics Inc. Security Advisory
Title: IMAP/POP Vulnerability
Title: CERT CA-97.09
Number: 19980302-01-I
Date: March 25, 1998
______________________________________________________________________________
Silicon Graphics provides this information freely to the SGI user community
for its consideration, interpretation, implementation and use. Silicon
Graphics recommends that this information be acted upon as soon as possible.
Silicon Graphics provides the information in this Security Advisory on
an "AS-IS" basis only, and disclaims all warranties with respect thereto,
express, implied or otherwise, including, without limitation, any warranty
of merchantability or fitness for a particular purpose. In no event shall
Silicon Graphics be liable for any loss of profits, loss of business, loss
of data or for any indirect, special, exemplary, incidental or consequential
damages of any kind arising from your use of, failure to use or improper
use of any of the instructions or information in this Security Advisory.
______________________________________________________________________________
As a followup to the CERT(sm) Advisory CA-97.09 "Vulnerability in IMAP and
POP", SGI has investigated this information and provides the following
information.
- -----------------------
- --- Issue Specifics ---
- -----------------------
The Internet Mail Access Protocol (IMAP) & Post Office Protocol (POP)
provide users with an alternative means to process and retrieve their email.
A vulnerability has been discovered in IMAP4 & POP3 that allows remote
users to obtain root access.
Silicon Graphics sells and supports the Netscape Mail/Messaging Servers
for IRIX which use IMAP4 & POP3 however, their implementations are not
vulnerable to this issue and no further action is required.
More information about Netscape product security can be found at the
following URL:
http://home.netscape.com/assist/security/
- ------------------------
- --- Acknowledgments ---
- ------------------------
Silicon Graphics wishes to thank the CERT Coordination Center and
Netscape for their assistance in this matter.
- -----------------------------------------------------------
- --- Silicon Graphics Inc. Security Information/Contacts ---
- -----------------------------------------------------------
If there are questions about this document, email can be sent to
cse-security-alert@sgi.com.
------oOo------
Silicon Graphics provides security information and patches for
use by the entire SGI community. This information is freely
available to any person needing the information and is available
via anonymous FTP and the Web.
The primary SGI anonymous FTP site for security information and patches
is sgigate.sgi.com (204.94.209.1). Security information and patches
are located under the directories ~ftp/security and ~ftp/patches,
respectively. The Silicon Graphics Security Headquarters Web page is
accessible at the URL http://www.sgi.com/Support/security/security.html.
For issues with the patches on the FTP sites, email can be sent to
cse-security-alert@sgi.com.
For assistance obtaining or working with security patches, please
contact your SGI support provider.
------oOo------
Silicon Graphics provides a free security mailing list service
called wiretap and encourages interested parties to self-subscribe
to receive (via email) all SGI Security Advisories when they are
released. Subscribing to the mailing list can be done via the Web
(http://www.sgi.com/Support/security/wiretap.html) or by sending email
to SGI as outlined below.
% mail wiretap-request@sgi.com
subscribe wiretap <YourEmailAddress>
end
^d
In the example above, <YourEmailAddress> is the email address that you
wish the mailing list information sent to. The word end must be on a
separate line to indicate the end of the body of the message. The
control-d (^d) is used to indicate to the mail program that you are
finished composing the mail message.
------oOo------
Silicon Graphics provides a comprehensive customer World Wide Web site.
This site is located at http://www.sgi.com/Support/security/security.html.
------oOo------
For reporting *NEW* SGI security issues, email can be sent to
security-alert@sgi.com or contact your SGI support provider. A
support contract is not required for submitting a security report.
______________________________________________________________________________
This information is provided freely to all interested parties and may
be redistributed provided that it is not altered in any way, Silicon
Graphics is appropriately credited and the document retains and
includes its valid PGP signature.
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[ End Silicon Graphic Inc. Update ]
_______________________________________________________________________________
CIAC wishes to acknowledge the contributions of CERT for the
information contained in this bulletin.
_______________________________________________________________________________
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