Re: Linux as a Server

Michael H. Warfield (mhw@alcove.wittsend.com)
Sun, 2 Aug 1998 11:33:20 -0400 (EDT)


I've had a few requests for this so I am reposting the CERT advisory
concerning the imapd vulnerability. It also has URL's for getting the
latest versions (as of the advisory) for the University of Washington
IMAP package.

One addition note... There was some confusion over build numbers
and the standalone imap package vs the imap package included with pine
at the UW site. Do NOT use the imap package in pine. At least at one point
they had the same build numbers, but the pine version was broken and the
separate package was not. Pay close attention to the section titled
"University of Washington" in the advisory.

Michael H. Warfield enscribed thusly:
> Yury S.Shramko enscribed thusly:
> > On Sat, 1 Aug 1998, Thorsten J. Lorenz wrote:
>
> > Only run imapd for get mail .
> > imap-4.1.BETA-11.i386.rpm from redhat - for example. It support POP3.
> > And setup sendmail in standart mode on your linux, and use one as smtp
> > relay for your windoze.
> > Your do not need use for it masquerading.
>
> NO! Do NOT run THAT version of imapd!!! There is a more recent
> version of imapd available! That version has a high risk remote root
> exploit vulernability!!!!
>
> Do NOT run ANYTHING prior to imap-4.1.FINAL
>
> Remote exploits exist in the wild and systems are being exploited!
>
> > > Hello,
>
> > > i am using Linux on my stationary PC and connect to it using my
> > > Notebook running Win95 (Sorry, but it is required :(). Now I want
> > > to connect to the Internet thru Linux (from the Win95 Notebook), but
> > > my ISP does not allow me to run a net. I could use masquerading, but
> > > as i understand, i can only use some services that way (ftp, e.g.)
> > > and Web-surfing is not include. Any suggestions how i could still do
> > > it. (Connecting the ISP with Linux works fine, no problems there).
> > >
> > > I would also appreciate to get my mail thru Linux. Where do i find
> > > information on how to set up a POP3-server. Will this work when my
> > > provider allows only client access or can i hide that, too.
>
> > Yury Shramko. Postmaster SAO RAN.

Mike

-- 
 Michael H. Warfield    |  (770) 985-6132   |  mhw@WittsEnd.com
  (The Mad Wizard)      |  (770) 925-8248   |  http://www.wittsend.com/mhw/
  NIC whois:  MHW9      |  An optimist believes we live in the best of all
 PGP Key: 0xDF1DD471    |  possible worlds.  A pessimist is sure of it!

===== Begin Attachment ===== CERT Advisory CA-98.09 =====

Date: Mon, 20 Jul 1998 14:29:50 -0400 From: CERT Advisory <cert-advisory@cert.org> Reply-To: cert-advisory-request@cert.org To: cert-advisory@coal.cert.org Subject: CERT Advisory CA-98.09 - imapd

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

Topic: Buffer Overflow in Some Implementations of IMAP Servers

- -------------------------------------------------------------------------

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.

- -------------------------------------------------------------------------

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.

- -------------------------------------------------------------------------

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

(c) Copyright 1994, 1995, 1996, 1997, 1998 Compaq Computer Corporation. All rights reserved.

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 aixserv@austin.ibm.com 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 -----------

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/.

- ------------------------------------------------------------------------- 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.

- -------------------------------------------------------------------------

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 cert@cert.org

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

cert-advisory-request@cert.org

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 cert@cert.org 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

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Revision history

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