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CERT* Advisory CA-98.09
Original issue date: July 20, 1998

Topic: Buffer Overflow in Some Implementations of IMAP Servers

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The CERT Coordination Center has received reports regarding a vulnerability
in some implementations of IMAP servers.

The CERT/CC recommends that anyone running a vulnerable version of this
software upgrade to the current vendor-recommended version. Until you can do
so, we suggest disabling the vulnerable IMAP server.

We will update this advisory as we receive additional information. We
encourage you to check our web site regularly for updates to this advisory
that may relate to your site.

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I. Description

The CERT Coordination Center has received reports regarding a buffer
overflow in some implementations of IMAP servers. The overflow is in library
code from the University of Washington IMAP server that handles SASL
server-level authentication. This vulnerability is different from the one
discussed in CERT Advisory CA-97.09.imap_pop. Information about this
vulnerability has been posted to various public mailing lists and
newsgroups.

All versions of the University of Washington IMAP server prior to the final
(frozen, non-beta) version of imap-4.1 that support SASL server-level
authentication are vulnerable. The vulnerability affects all University of
Washington IMAP4rev1 servers prior to v10.234. Also, any v10.234 server that
was distributed with Pine 4.0 or any imap-4.1.BETA is vulnerable.

Additionally, the vulnerability is present in other IMAP servers that use
library code from the University of Washington IMAP server to handle SASL
server-level authentication.

IMAP servers that share no code with the University of Washington server are
not vulnerable.

Some operating systems ship with a vulnerable version of this software
installed and enabled by default. Please refer to the Vendor Information
section below for more information about your vendor.

II. Impact

Remote intruders can execute arbitrary commands under the privileges of the
process running the vulnerable IMAP server. If the vulnerable IMAP server is
running as root, remote intruders can gain root access.

III. Solution

A. Determine if your version of imapd is vulnerable

To determine if a system is vulnerable, first telnet to port 143 on
that host. If it is running an IMAP server, the banner will show the
version. For example:

% telnet host.your.domain.com 143
Trying 123.123.123.123...
Connected to host.
Escape character is '^]'.
* OK host.your.domain.com IMAP4rev1 v10.190 server ready

In the above example, the IMAP server is the University of Washington
IMAP4rev1 v10.190. Since all University of Washington IMAP4rev1 servers
prior to v10.234 are vulnerable, the server in the above example is
vulnerable.

Please consult the Vendor Information section below for information
about other vulnerable IMAP servers.

B. Install the most recent version of imapd

Obtain and install the most recent version, or patch for your IMAP
server. Appendix A contains input from vendors who have provided
information for this advisory.

C. Workaround

If you are unable to upgrade to a version that is not vulnerable, we
urge you to disable the IMAP server until you are able to address the
problem.

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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.

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IMAP Server Vendors

Cyrus

This does not affect the Cyrus imapd. Cyrus imapd shares no code with
the University of Washington imapd.

Esys Corporation

We are not affected by the problem described in the advisory. We do not
ship any University of Washington based software at this time. We have
never shipped any of the IMAP 4.x software from the University of
Washington.

NEC Corporation

The University of Washington imapd is shipped with our product
"Mobilenet/IMAP" and so it is vulnerable.

Netscape

Netscape Messaging Server 3.55 and before are susceptible to this
vulnerability. However, it should be noted that Netscape Messaging
Server (any version) does NOT run as root and therefore, the exposure
is much more limited than the University of Washington example.
Regardless, we have released a patch available at
http://help.netscape.com/products/server/messaging which
addresses this vulnerability.

Sun Microsystems

Sun Microsystems is working on patches for Solstice Internet Mail Server
product versions 2.0, 3.1 and 3.2.

University of Washington

A security problem has been detected with the University of Washington
IMAP server that is included in the Pine 4.00 distribution. This will
be fixed in the forthcoming Pine 4.01 maintenance release. Until then,
if you are using the UW IMAP server, please update it with the
following distribution:

ftp://ftp.cac.washington.edu/mail/imap.tar.Z

This vulnerability affects all IMAP4rev1 servers prior to
v10.234. v10.234 may or may not be vulnerable; if it came from Pine
4.00 or from any imap-4.1.BETA then it is vulnerable. IMAP2bis
servers are immune. This problem is also fixed in the imap-4.2
toolkit, which is tentatively expected to be released in
conjunction with Pine 4.01. Any IMAP4rev1 server whose version
starts with "v11" will be immune.

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Operating System Vendors

Berkeley Software Design, Inc.

The version of IMAP shipped with BSD/OS 2.1 and 3.0/3.1 is the older
version which does not include the vulnerability.

The version of IMAP which will be included in the upcoming 4.0 release
has been updated to include the security fixes.

Caldera Linux

Caldera: releasing patched imap-4.1; will release imap-4.2 as soon as
it becomes available.

URL: ftp://ftp.caldera.com/pub/OpenLinux/updates/1.2/010

6df741b4217f03bf773b54509a7d283a imap-4.1.BETA-5.i386.rpm
d3526121c68b611524fc72746204d752 imap-4.1.BETA-5.src.rpm

Compaq Computer Corporation

SOURCE: Compaq Computer Corporation
Compaq Services
Software Security Response Team USA

This reported problem is not present for the as shipped,
Compaq's Digital ULTRIX or Compaq's Digital UNIX
Operating Systems Software.

- Compaq Computer Corporation

Data General

We are investigating. We will provide an update when our
investigation is complete.

FreeBSD

FreeBSD does not ship default with imap. However, there is a version
of imapd from Washington University in the FreeBSD ports collections,
known as imap-uw.

If anyone is using the imap port, we suggest fetching the latest revision
of imap and manually install it, or wait until the FreeBSD port is updated
and reinstall imap-uw using the ports system.

You can check the ports status at:
http://www.freebsd.org/ports/mail.html

Fujitsu

Our operating system, UXP/V, does not support imapd. Therefore, it is
not vulnerable to the above vulnerability.

Hewlett-Packard Company

HP does not ship the University of Washington IMAP server.

IBM Corporation

The version of imapd shipped with AIX 4.2 and 4.3 is vulnerable. We
are currently working on the following fixes which will be available
soon:

AIX 3.2.x: imapd not shipped (not vulnerable)
AIX 4.1.x: imapd not shipped (not vulnerable)
AIX 4.2.x: IX80446
AIX 4.3.x: IX80447

To Order
--------
APARs may be ordered using Electronic Fix Distribution (via FixDist)
or from the IBM Support Center. For more information on FixDist,
reference URL:

http://aix.software.ibm.com/aix.us/swfixes/

or send e-mail to This email address is being protected from spambots. You need JavaScript enabled to view it. with a subject of "FixDist".

IBM and AIX are registered trademarks of International Business Machines
Corporation.

NetBSD

NetBSD does not ship the UW imapd daemon in its standard or development
operating system releases. Our optional package system also does not
include it at this time.

OpenBSD

OpenBSD has never shipped an imap daemon.

Red Hat Linux

Serious security problems have been found in all versions of imap shipped
with Red Hat Linux. If "rpm -q imap" shows that imap is installed on
your system, please upgrade to these new imap releases immediately, or
remove imap by running "rpm -e imap". Note that Red Hat's imap package
also provides a POP server, so only remove it if you don't need to provide
POP services.

Thanks to everyone who helped find these problems, Olaf Kirch in particular.

Red Hat 5.0 and 5.1
-------------------

i386:
rpm -Uvh ftp://ftp.redhat.com/updates/5.0/i386/imap-4.1.final-1.i386.rpm

alpha:
rpm -Uvh ftp://ftp.redhat.com/updates/5.0/alpha/imap-4.1.final-1.alpha.rpm

SPARC:
rpm -Uvh ftp://ftp.redhat.com/updates/5.0/sparc/imap-4.1.final-1.sparc.rpm

Red Hat 4.2
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i386:
rpm -Uvh ftp://ftp.redhat.com/updates/4.2/i386/imap-4.1.final-0.i386.rpm

alpha:
rpm -Uvh ftp://ftp.redhat.com/updates/4.2/alpha/imap-4.1.final-0.alpha.rpm

SPARC:
rpm -Uvh ftp://ftp.redhat.com/updates/4.2/sparc/imap-4.1.final-0.sparc.rpm

The Santa Cruz Operation, Inc.

The following SCO products are vulnerable:

- SCO UnixWare 7

SCO OpenServer 5.0, SCO CMW+ 3.0, SCO Open Desktop/Open Server 3.0, and
UnixWare 2.1 is not vulnerable as University of Washington imapd is not
included in these platforms.

Binary versions of University of Washington imapd will be available
shortly from the SCO ftp site:

ftp://ftp.sco.com/SSE/sse014.ltr - cover letter
ftp://ftp.sco.com/SSE/sse014.tar.Z - replacement binaries

This fix is a binary for the following SCO operating systems:

- SCO UnixWare 7

For the latest security bulletins and patches for SCO products,
please refer to http://www.sco.com/security/.

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The CERT Coordination Center thanks Olaf Kirch of Caldera Linux for
discovering and reporting the vulnerability. Additionally, we would like to
thank Mark Crispin and Lori Stevens of the University of Washington for
providing technical details and support in the development of the advisory.

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If you believe that your system has been compromised, contact the CERT
Coordination Center or your representative in the Forum of Incident Response
and Security Teams (see http://www.first.org/team-info/)

CERT/CC Contact Information

Email This email address is being protected from spambots. You need JavaScript enabled to view it.

Phone +1 412-268-7090 (24-hour hotline)

CERT personnel answer 8:30-5:00 p.m. EST(GMT-5) / EDT(GMT-4) and are on call
for emergencies during other hours.

Fax +1 412-268-6989

Postal address:

CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
USA

Using encryption

We strongly urge you to encrypt sensitive information sent by email. We can
support a shared DES key or PGP. Contact the CERT/CC for more information.

Location of CERT PGP key

ftp://ftp.cert.org/pub/CERT_PGP.key

Getting security information

CERT publications and other security information are available from

http://www.cert.org/
ftp://ftp.cert.org/pub/

CERT advisories and bulletins are also posted on the USENET newsgroup
comp.security.announce
To be added to our mailing list for advisories and bulletins, send email to

This email address is being protected from spambots. You need JavaScript enabled to view it.

In the subject line, type

SUBSCRIBE your-email-address

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Copyright 1998 Carnegie Mellon University. Conditions for use, disclaimers,
and sponsorship information can be found in
http://www.cert.org/legal_stuff.html and ftp://ftp.cert.org/pub/legal_stuff.
If you do not have FTP or web access, send mail to This email address is being protected from spambots. You need JavaScript enabled to view it. with
"copyright" in the subject line.

*CERT is registered in the U.S. Patent and Trademark Office.

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The authoritative version of this file is at:
http://www.cert.org/advisories/CA-98.09.imapd.html

A text only version of this file is at:
ftp://ftp.cert.org/pub/cert_advisories/CA-98.09.imapd.html

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Revision history

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