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- -----BEGIN PGP SIGNED MESSAGE-----
-
- =============================================================================
- CERT(sm) Advisory CA-95:13
- Original issue date: October 19, 1995
- Last revised: August 30, 1996
- Information previously in the README was inserted
- into the advisory.
-
- A complete revision history is at the end of this file.
-
- Topic: Syslog Vulnerability - A Workaround for Sendmail
- - -----------------------------------------------------------------------------
-
- The CERT Coordination Center has received reports of problems with the
- syslog(3) subroutine. To the best of our current knowledge, the problem is
- present in virtually all versions of the UNIX Operating System except the
- following:
-
- Sony's NEWS-OS 6.X
- SunOS 5.5 (Solaris 2.5)
- Linux with libc version 4.7.2, released May 1995
-
- We have received reports indicating that the vulnerability is being exploited
- with a script that has been written to be used with sendmail.
-
- This advisory includes a workaround that you can use with sendmail. It
- *does not* include workarounds for any other programs that use the syslog(3)
- subroutine--telnetd, ftpd, httpd, etc.
-
- The CERT Coordination Center recommends installing all appropriate
- syslog-related patches as soon as they are available from vendors. But, in
- the meantime, we suggest addressing at least the syslog problem in sendmail by
- installing sendmail version 8.7.1. We are aware that several workarounds
- concerning the syslog vulnerability have been published on the Internet, but
- the CERT staff has not formally evaluated them.
-
- We will update this advisory as we receive additional information.
- Please check advisory files regularly for updates that relate to your site.
- - -----------------------------------------------------------------------------
-
- I. Description
-
- The syslog(3) subroutine uses an internal buffer for building messages
- that are sent to the syslogd(8) daemon. This subroutine does no range
- checking on data stored in this buffer. It is possible to overflow the
- internal buffer and rewrite the subroutine call stack. It is then
- possible to execute arbitrary programs.
-
- This problem is present in virtually all versions of the UNIX
- Operating System except the following:
-
- Sony's NEWS-OS 6.X
- SunOS 5.5 (Solaris 2.5)
- Linux with libc version 4.7.2 released in May, 1995
-
- The sendmail(8) program uses the syslog(3) subroutine, and a script has
- been written and is being used to exploit the vulnerability.
-
- II. Impact
-
- Local and remote users can execute commands. Prior access to the system
- is not needed. Exploitation can lead to root access.
-
- III. Solution
-
- We recommend that you do all of A, B, and C.
-
- A. Install syslog patches from your vendor when they become available.
-
- Information we received from vendors as of the issue date of this
- advisory is attached as Appendix A. We will update the appendix as
- vendors send updated information.
-
- When you install patches, you will need to recompile/relink any
- programs built on your system that have been compiled without shared
- libraries, that is, compiled statically. Be especially careful of
- programs that contain their own versions of the syslog(3) subroutine.
- You may need to do significant extra work to compile those programs to
- use the vendor-supplied patches.
-
- B. Install sendmail version 8.7.1.
-
- NOTE: This workaround addresses the syslog(3) vulnerability in
- sendmail only. The vulnerability still exists in all other
- programs that use syslog(3).
-
- When your vendor(s) provides a patch, we recommend that you rebuild
- sendmail version 8.7.1 with the patched syslog(3) and place that
- newly compiled version into service.
-
- Sendmail is available by anonymous FTP from
-
- ftp://info.cert.org/pub/tools/sendmail/
- ftp://ftp.cs.berkeley.edu/ucb/sendmail/
- ftp://ftp.auscert.org.au/pub/mirrors/ftp.cs.berkeley.edu/ucb/sendmail/
- ftp://ftp.cert.dfn.de/pub/tools/net/sendmail/
-
- Checksum:
-
- MD5 (sendmail.8.7.1.tar.Z) = 4a66d07a059d1d5af5e9ea53ff1b396a
-
- Depending upon your currently installed sendmail program, switching to
- a different sendmail may require significant effort (such as rewriting
- the sendmail.cf file). See Section VI for additional notes on
- installation.
-
- In addition, Sections IV and V below contain scripts for building
- sendmail 8.7.1 for SunOS 4.1.X and Solaris 2.X, respectively.
-
- C. Install smrsh.
-
- To restrict the sendmail program mailer facility, install and
- use the sendmail restricted shell program (smrsh). We recommend
- that you do this regardless of whether you use the vendor's supplied
- sendmail or you install sendmail version 8.7.1.
-
- Smrsh is now included in the sendmail 8.7.1 distribution in the
- subdirectory smrsh. See the RELEASE_NOTES file for a description
- of how to integrate smrsh into your sendmail configuration file.
-
- Please note that although smrsh does not address the vulnerability
- described in this advisory, a description of smrsh is provided for
- completeness. We recommend that you install and use smrsh with *all*
- versions of sendmail.
-
- IV. Building this package for SunOS 4.1.X
-
- Here is a script that is given as an illustration of how to build
- sendmail 8.7.1 for SunOS 4.1.X. Please refer to READ_ME in the src
- subdirectory for a more complete explanation of other options available
- during the compilation process.
-
- % uname -sr
- SunOS 4.1.2
- % ls
- sendmail.8.7.1.tar.Z
- % zcat sendmail.8.7.1.tar.Z | tar xf -
- % cd sendmail-8.7.1/src
- % ./makesendmail LIBS='-lresolv' DBMDEF='-DNDBM -DNIS' \
- INCDIRS= LIBDIRS= sendmail
- Configuration: os=SunOS, rel=4.1.2, rbase=4, arch=sun4, sfx=
- Creating obj.SunOS.4.1.2.sun4 using Makefile.SunOS
- Making dependencies in obj.SunOS.4.1.2.sun4
- Making in obj.SunOS.4.1.2.sun4
- ...
-
- See Section VI for final installation steps.
-
- V. Building this package for Solaris 2.X
-
- Here is a typescript that is given as an illustration for how to build
- sendmail 8.7.1 for Solaris 2.X. Note that this procedure assumes that
- you have the GNU gcc system. The examples below used gcc version 2.6.3.
- Again, please refer to READ_ME in the src sub-directory for a more
- complete explanation of other options available during the compilation
- process.
-
- % uname -sr
- SunOS 5.4
- % ls
- sendmail.8.7.1.tar.Z
- % zcat sendmail.8.7.1.tar.Z | tar xf -
- % cd sendmail-8.7.1/src
- % ./makesendmail LIBS='-lresolv -lsocket -lnsl -lelf' \
- INCDIRS= LIBDIRS= sendmail
- Configuration: os=SunOS, rel=5.4, rbase=5, arch=sun4, sfx=
- Creating obj.SunOS.5.4.sun4 using Makefile.SunOS.5.4
- Making dependencies in obj.SunOS.5.4.sun4
- ...
-
- Note: If you wish sendmail version 8.7.1 to use the aliases and
- configuration file directory conventions from SunOS 5.4, use the
- following command:
-
- ./makesendmail LIBS='-lresolv -lsocket -lnsl -lelf' \
- ENVDEF='-DSOLARIS=204 -DUSE_VENDOR_CF_PATH' INCDIRS= \
- LIBDIRS= sendmail
-
- VI. Final Installation Notes
-
- Sendmail can then be installed and configured with new configuration
- files as needed. We strongly recommend that if you change to sendmail
- 8.7.1, you also change to the configuration files that are provided with
- that version.
-
- Significant work has been done to make this task easier. It is now
- possible to build a sendmail configuration file (sendmail.cf) using
- the configuration files provided with this release. Consult the
- cf/READ_ME file for a more complete explanation. We recommended that you
- create your configuration files using this method because it provides a
- technique for incorporating any future changes to sendmail into your
- configuration files.
-
- In addition, we recommend that you recreate your configuration file
- (sendmail.cf) using the configuration files provided with 8.7.1.
-
- Finally, for Sun users, a paper is available to help you convert your
- sendmail configuration files from the Sun version of sendmail to one that
- works with version 8.7.1. The paper is entitled "Converting Standard Sun
- Config Files to Sendmail Version 8" and was written by Rick McCarty of
- Texas Instruments Inc. It is included in the distribution and is located
- in contrib/converting.sun.configs.
-
- ^L
- ..............................................................................
-
- Appendix A: Vendor Information
-
- Below is information we have received from vendors concerning the
- vulnerability described in this advisory. If you do not see your vendor's
- name, please contact the vendor directly for information.
-
- In addition to vendor information, note that the freely available Linux with
- libc version 4.7.2, released May 1995, is not vulnerable.
-
- - --------------------
- Eric Allman
-
- Neither sendmail version 8.7.3 nor 8.7.1 is vulnerable. Sendmail is
- available by anonymous FTP from
-
- ftp://info.cert.org/pub/tools/sendmail
- ftp://ftp.cs.berkeley.edu/ucb/sendmail
- ftp://ftp.auscert.org.au/pub/mirrors/ftp.cs.berkeley.edu/ucb/sendmail
- ftp://ftp.cert.dfn.de/pub/tools/net/sendmail
-
- MD5 (sendmail.8.7.3.tar.Z) = 3c3891c92500d12d60a61aaa1d01b533
-
- - --------------------
- Berkeley Software Design, Inc.
-
- Users of BSD/OS V2.0 and V2.0.1 by Berkeley Software Design, Inc. should
- install patch U201-001 which works for both versions. The patch is available
- to all BSDI customers in: ftp://ftp.bsdi.com/bsdi/patches/
-
- md5 checksum: 88b3fd8c83a5926589d7b87b55bc4e14
-
- - --------------------
- Convex Computer Corporation
-
- The CERT Coordination Center inadvertently omitted the Convex entry
- from the original advisory:
-
- Vulnerable: ConvexOS (all releases)
- SPPUX (all releases)
-
- A patch is being developed to address this vulnerability in currently
- supported releases as detailed below. Contact the Convex Technical
- Assistance Center 1-800-952-0379 to obtain information and patches.
-
- There are no known automated attack programs in existence for Convex or
- SPP architectures. Development of such a program would require access
- to such a machine, as well as detailed knowledge of the architecture.
- However, the only completely secure work-around at this time would be to
- disable sendmail (known to have been successfully attacked on other
- architectures), as well as other daemons which can potentially log
- user-supplied strings. Note that the user-supplied strings do not have
- to actually be routed by syslogd in order for this vulnerability to
- occur. At this time we do not have a canonical list of affected
- software; sendmail is the only known-vulnerable agent.
-
- It should also be noted that Convex machines make use of a "SPU"
- workstation (also referred to as a "test station") which controls the
- machine; these workstations are vulnerable if sendmail is enabled on
- those workstations and the SPU or test station is located on an
- accessible network. Convex recommends disabling sendmail on SPU and
- test-station workstations until a patch can be obtained from Convex.
-
- Currently supported OS releases as of Sep 1, 1995:
-
- ConvexOS 10.1, 10.2, 11.0, 11.1
- SPPUX 3.x
-
- - --------------------
- Cray Research
-
- Information about fixes for the syslog problem can be found in FN #2011,
- dated October 10, 1995. Customers should receive this information from
- their Cray Research service representative.
-
- For all source installations, your Cray Research service representative can
- obtain the fix via the getfix tool.
-
- Due to the number of executables which use this library routine, it is not
- possible to provide getfix packages for all binary installations. UNICOS
- binary update packages 8.0.4.2 and 9.0.1.2 include this mod.
-
- FIX AVAILABILITY as of Feb. 1996
- --------------------------------
- Release Level Fix Package
- Affected Product Containing Fix Availability
- ================ ============== ===========
- UNICOS 8.0 UNICOS 8.0.4.2 * source only
- UNICOS 8.3 ** source only
- UNICOS 9.0 UNICOS 9.0.1.2 *** source only
-
- * Released for all platforms.
- ** No more updates planned.
- *** Released for X-MP, Y-MP, C-90 and T-90 platforms but has not yet
- released for YMP-EL and J-90 platforms.
-
-
- - --------------------
- Data General Corporation
-
- The DG/UX operating system is NOT vulnerable to this problem. This
- includes all currently supported release, DG/UX 5.4 Release 3.00, DG/UX 5.4
- Release 3.10, DG/UX Release 4.10 and all related Trusted DG/UX products.
-
- - --------------------
- Digital Equipment Corporation
-
- For updated information, please refer to the Digital Equipment
- Corporation Vendor Bulletin #96.0383, available in
-
- ftp://info.cert.org/pub/vendors/dec/dec_96.0383
-
- Note: Non-contract/non-warranty customers should contact
- local Digital support channels for information
- regarding these kits.
-
- As always, Digital urges you to periodically review your system
- management and security procedures. Digital will continue to review
- and enhance the security features of its products and work with
- customers to maintain and improve the security and integrity of their
- systems.
-
- - --------------------
- Hewlett-Packard Company
-
- Included below is information obtained from the February 7th, 1996,
- Hewlett Packard Security Bulletin, HPSBUX9602-029 "Security
- Vulnerability in HP-UX syslog(3) subroutine."
-
- It has been found that all HP-UX systems prior to HP-UX 10.10 have
- this vulnerability.
-
- The vulnerability can be eliminated from releases 9.X and 10.0X of
- HP-UX by applying a patch. Releases of HP-UX prior to 9.X must
- upgraded to release 9.X or higher to escape the vulnerability,
- which is fixed in the HP-UX 10.10 release. There are no work-around
- solutions known.
-
- Hewlett-Packard recommends that all customers concerned with the
- security of their HP-UX systems either apply the appropriate
- patch or change perform the actions described above as soon as
- possible.
-
- Hewlett Packard's HP-UX patches are available via email
- and World Wide Web.
-
- To obtain a copy of the HP SupportLine email service user's
- guide, send the following in the TEXT PORTION OF THE MESSAGE to
- support@us.external.hp.com (no Subject is required):
-
- send guide
-
- The users guide explains the process for downloading HP-UX
- patches via email and other services available.
-
- World Wide Web service for downloading of patches
- is available via our URL:
-
- (http://us.external.hp.com)
-
- Patches:
- PHCO_6595 (series 700/800, HP-UX 10.0 & 10.01), or
- PHCO_6598 (series 800, HP-UX 9.0 & 9.04), or
- PHCO_6597 (series 700, HP-UX 9.0[1357]), or
- PHCO_6224 (series 300/400, HP-UX 9.0, 9.01, 9.03 & 9.1), or
- PHCO_6162 (series 700, HP-UX 9.08 BLS), or
- PHCO_6161 (series 700, HP-UX 9.09 BLS), or
- PHCO_6160 (series 700, HP-UX 9.09+ BLS), or
- PHCO_6157 (series 700, HP-UX 10.09 BLS CMW).
-
-
- Availability:
- All patches are available now, except for the BLS patches,
- which will be available after 29 February, 1996. Contact your
- FCO representative for patch availability.
-
- Further details are provided in Hewlett-Packard Security Bulletin,
- "HPSBUX9602-029 Security Vulnerability in HP-UX syslog(3) subroutine."
-
- World Wide Web service for browsing of bulletins is available via
- our URL:
- http://us.external.hp.com
-
- Choose "Support news", then under Support news,
- Choose "Security Bulletins"
-
- - -------------------
- IBM Corporation
-
- Both fixes are now currently available. Please reference the
- following fixes:
- AIX 4.1 - IX53718
- AIX 3.2 - IX53358
-
- - --------------------
- Open Software Foundation
-
- OSF cannot reproduce the security hole in OSF/1. However we have reproduced
- the problem with syslog(3). We have a fix for the syslog(3) problem. Support
- customers should contact OSF for the fix. The fix will be included in the
- OSF/1 R1.3.2 update release.
-
- - --------------------
- The Santa Cruz Operation (SCO)
-
- The "SCO Networking Maintenance Supplement for SCO OpenServer 5"
- addresses the syslog() problem for all ELF binaries in the product.
- This supplement is available in:
-
- ftp://ftp.sco.COM/Supplements/net100/
-
- This includes all the standard network utilities that are often the
- target of a syslog() attack, such as sendmail. The product also
- includes a few COFF binaries that use syslog(). These binaries will
- be corrected in an upcoming Supplement.
-
- - --------------------
- Silicon Graphics Inc.
-
- Silicon Graphics released Security Advisory 19951001-01-P825 and patch 825
- to address the specifics of CERT Advisory CA-95:13. Please note that patch
- 1146 (Security Advisory 19960203-01-P1146) supersedes patch 825. This patch
- addresses additional security problems in the "sendmail" program.
- Please refer to SGI Advisory 19960203-01-P1146 for further information
- on these additional security problems, and the location and checksums of
- this patch.
-
- Silicon Graphics has continued to investigate the 8lgm reported syslog
- vulnerability. A review of utilities supplied with the IRIX 5.3, 6.0, 6.0.1
- and 6.1 environments that use syslog has been performed. Silicon Graphics
- has not discovered any syslog vulnerabilities in these utilities.
-
- Past SGI Advisories and security patches can be obtained via
- anonymous FTP from sgigate.sgi.com or its mirror, ftp.sgi.com.
-
- - --------------------
- Solbourne (Grumman)
-
- Solbourne 2.5 is not vulnerable.
-
- - --------------------
- Sony Corporation
-
- NEWS-OS 6.0.3 and 6.1 are not vulnerable.
-
- - --------------------
- Sun Microsystems, Inc.
-
- SunOS 5.5 is not vulnerable.
-
- Sun Microsystems has made the following patches available to address this
- vulnerability:
-
- PATCH # VERSION RELEASED
- --------- ----------- ------------
- 100891-13 - SunOS 4.1.3 Oct 27, 1995 (International)
- 101558-07 - SunOS 4.1.3_U1 Oct 27, 1995 (International)
- 102545-04 - SunOS 4.1.4 Nov 16, 1995 (International)
- 100890-13 - SunOS 4.1.3 Feb 21, 1996 (US only)
- 101759-04 - SunOS 4.1.3_U1 Feb 21, 1996 (US only)
- 102544-04 - SunOS 4.1.4 Feb 21, 1996 (US only)
-
- 102903-01 - Solaris 2.3 Nov 2, 1995
- 101945-37 - Solaris 2.4 Feb. 29, 1996
- 102905-01 - Solaris 2.4_x86 Nov 2, 1995
-
- Note also that the following patches:
-
- 100890-13 - SunOS 4.1.3 Feb 21, 1996 (US only)
- 101759-04 - SunOS 4.1.3_U1 Feb 21, 1996 (US only)
- 102544-04 - SunOS 4.1.4 Feb 21, 1996 (US only)
-
- require that you contact your Sun Solution Center or other SunSoft
- authorized service provider (ASP) in the U.S. to obtain a copy of the
- actual patch.
-
- Sun Security Bulletins are available via the security-alert alias
- (security-alert@sun.com) and on SunSolve (http://sunsolve1.sun.com).
-
- - ---------------------------------------------------------------------------
- The CERT Coordination Center staff thanks Eric Allman and Wolfgang Ley for
- their involvement in the development of this advisory, and thanks Karl
- Strickland and Neil Woods for reporting the vulnerability.
- - ---------------------------------------------------------------------------
-
- 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 (FIRST).
-
- If you wish to send sensitive incident or vulnerability information to
- CERT staff by electronic mail, we strongly advise that the email be
- encrypted. The CERT Coordination Center can support a shared DES key, PGP
- (public key available via anonymous FTP on info.cert.org), or PEM (contact
- CERT staff for details).
-
- Internet email: cert@cert.org
- Telephone: +1 412-268-7090 (24-hour hotline)
- CERT personnel answer 8:30 a.m.-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
-
- CERT advisories and bulletins are posted on the USENET newsgroup
- comp.security.announce. If you would like to have future advisories and
- bulletins mailed to you or to a mail exploder at your site, please send mail
- to cert-advisory-request@cert.org.
-
- Past CERT publications, information about FIRST representatives, and other
- information related to computer security are available for anonymous
- FTP from info.cert.org.
-
-
- Copyright 1995, 1996 Carnegie Mellon University
- This material may be reproduced and distributed without permission provided it
- is used for noncommercial purposes and the copyright statement is included.
-
- CERT is a service mark of Carnegie Mellon University.
-
- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- Revision history
-
- Aug. 30, 1996 Information previously in the README was inserted
- into the advisory.
- July 05, 1996 Appendix, Digital- Added pointer to updated information.
- July 01, 1996 Appendix, SGI - Added additional information
- Apr. 17, 1996 Appendix, SCO - Added an entry for SCO
- Mar. 29, 1996 Appendix, Sun - Modified the Sun entry
- Feb. 27, 1996 Appendix, Hewlett-Packard & Sun - Updated entries
- Feb. 06, 1996 Appendix, Allman & Cray - Updated entries
- Dec. 19, 1995 Appendix, Digital - Modified Digital entry
- Nov. 07, 1995 Appendix, IBM, SGI, Sun - Updated entries
- Nov. 07, 1995 Sec. III.C - Added note recommending smrsh though it doesn't
- address the particular vulnerability described in the advisory
- Oct. 27, 1995 - Appendix, Convex, Data General Hewlett-Packard, IBM - Added
- text
-
-
-
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