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Security Bulletin 9722 DISA Defense Communications System
September 9, 1997 Published by: DISN Security Coordination Center
(SCC@NIC.MIL) 1-(800) 365-3642
The DISN SECURITY BULLETIN is distributed by the DISN SCC (Security Coordination Center) under DISA contract as a means of communicating information on network and host security exposures, fixes, and concerns to security and management personnel at DISN facilities. Back issues may be obtained via FTP from NIC.MIL [207.132.116.5] using login= "anonymous" and password="guest". The bulletin pathname is scc/sec-yynn (where "yy" is the year the bulletin is issued and "nn" is a bulletin number, e.g. scc/sec-9705.txt). These are also available at our WWW site, http://nic.mil.
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! !
! The following important advisory was issued by the Automated !
! Systems Security Incident Support Team (ASSIST) and is being !
! relayed unedited via the Defense Information Systems Agency's !
! Security Coordination Center distribution system as a means !
! of providing DISN subscribers with useful security information. !
! !
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___ ___ _____ ___ _____ | /
/\ / \ / \ | / \ | | / Integritas
/ \ \___ \___ | \___ | | < et
/____\ \ \ | \ | | \ Celeritas
/ \ \___/ \___/ __|__ \___/ | |_____\
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Release date: 08 Sep 1997
PLATFORM: Mostly UNIX systems. See list below
IMPACT: Protocols relying on DNS resolution for authentication
purposes are unreliable. These protocols include, but not limited to rsh, rlogin, NFS, etc. This vulnerability is actively being exploited.
SOLUTIONS: Apply fixes mentioned in Section III as
soon as possible.
[ Beginning of CERT Bulletin ]
=============================================================================
Introduction - Clarified that 4.9.6 is not vulnerable.
Section III - Added a note why sites should upgrade to 8.1.1.
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*** This advisory supersedes CA-96.02. ***
Several vulnerabilities in the Berkeley Internet Name Daemon (BIND) have been fixed in the current version of BIND. One of those vulnerabilities is now being exploited, a vulnerability that results in cache poisoning (malicious or misleading data from a remote name server is saved [cached] by another name server).
The vulnerability has been fixed in BIND version 4.9.6; however, we recommend upgrading according to our instructions in Section III.B or installing vendor patches (see Appendix A). We also urge you to take the additional precautions described in Section III.C.
We will update this advisory as we receive additional information. Please check our advisory files regularly for updates that relate to your site.
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The Berkeley Internet Name Daemon (BIND) is an implementation of the Domain Name Service (DNS) written primarily for UNIX Systems. BIND consists of three parts:
The mapping between host names and IP addresses may be changed. As a result, attackers can inspect, capture, or corrupt the information exchanged between hosts on a network.
Install a patch from your vendor or implement the "best practice" workaround we recommend in Section III.B. In either case, take the extra precautions described in Section III.C.
Information from vendors can be found in Appendix A of this advisory;
we will update the appendix as we receive more information.
The "best practice" for operating the publicly available BIND
system can be either:
identical to that of version 4.9.6, version 8.1.1 is the version that will continue to undergo changes and improvements, hence our selection of its use as the "best practice."
1. Shared Object Client Subroutine Library
If your system and its programs rely on the shared object client
subroutine library that comes with some releases of BIND, probably
named libresolv.so, then you need the shared object subroutine
library and other client software from release 4.9.6. (As of
this writing, BIND version 8 does not yet support the client
part as a shared object library.) This client software is
available at
ftp://ftp.isc.org/isc/bind/src/4.9.6/bind-4.9.6-REL.tar.gz
MD5 (bind-4.9.6-REL.tar.gz) = 76dd66e920ad0638c8a37545a6531594
Follow the instructions in the file named INSTALL in the top-level
directory.
After installing this client part, install the server and tool
parts from release 8.1.1. This software is available at
ftp://ftp.isc.org/isc/bind/src/8.1.1/bind-src.tar.gz
MD5 (bind-src.tar.gz) = 7487b8d647edba2053edc1cda0c6afd0
Follow the instructions in the src/INSTALL file. Note that
this version will install the client libraries and header files in a non-standard place, /usr/local/lib and /usr/local/include. The src/INSTALL file describes what is being installed and where.
When you install release 4.9.6 first, its client, server, and
tools parts will be installed in the production locations. When you then install release 8.1.1, the server and tools parts will be overwritten by that release's versions, but the 4.9.6 client part will not.
2. No Shared Object Client Subroutine Library
If you do not need the shared object client subroutine library,
then you need only upgrade to release 8.1.1. This software is
available at
ftp://ftp.isc.org/isc/bind/src/8.1.1/bind-src.tar.gz
MD5 (bind-src.tar.gz) = 7487b8d647edba2053edc1cda0c6afd0
Follow the instructions in src/INSTALL. Note that the client
subroutine library and header files are installed in /usr/local/lib
and /usr/local/include respectively. To use these when building
other systems, you will need to refer to their installed locations.
Note: ftp://ftp.isc.org/isc/bind/src/ is mirrored in
Germany at ftp://ftp.cert.dfn.de/pub/tools/net/bind/src/
As new versions of BIND are released in the future, you will be able
to find them at these sites, as well as other mirrors. You can
also check ftp://info.cert.org/pub/latest_sw_versions/ for version
information.
C. Take additional precautions.
As good security practice in general, filter at a router all
name-based authentication services so that you do not rely on DNS information for authentication. This includes the services rlogin, rsh (rcp), xhost, NFS, and any other locally installed services that provide trust based on domain name 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.
Cray Research has determined that the version of
BIND shipped with all current releases of Unicos and Unicos/mk
are susceptible to the problem described in this advisory. We
are currently working on upgrading our version of BIND to the
4.9.6 release.
xref CASE ID: SSRT0494U
At the time of writing this document, patches(binary kits) are in progress and final patch testing is expected to begin soon.
Digital will provide notice of the completion/availability of the patches through AES services (DIA, DSNlink FLASH) and be available from your normal Digital Support channel.
DIGITAL EQUIPMENT CORPORATION AUG/97
----------------------------- ------
HP is vulnerable. Patches in process.
IBM is currently working on the following APARs which will be available soon:
APARs may be ordered using Electronic Fix Distribution (via FixDist) or from the IBM Support Center. For more information on FixDist, reference URL:
http://service.software.ibm.com/aixsupport/
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.
We are investigating this problem and will provide
updated information for this advisory when it becomes available.
The following SCO operating systems are vulnerable:
ftp://ftp.sco.com/SSE/sse008.ltr.Z - cover letter
ftp://ftp.sco.com/SSE/sse008.tar.Z - replacement binaries
The fix includes binaries for the following SCO operating systems:
======================
We are producing patches.
[ End of CERT Bulletin ]
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The ASSIST staff would like to thank the CERT Coordination Center for this advisory, as well as Paul Vixie and Wolfgang Ley for their contributions to this advisory.
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ASSIST is an element of the Defense Information Systems Agency (DISA), Global Operations and Security Center (GOSC), which provides service to the entire DoD community. Constituents of the DoD with questions about ASSIST or computer security issues, can contact ASSIST using one of the methods listed below. Non-DoD organizations/institutions, contact the Forum of Incident Response and Security Teams (FIRST) representative. To obtain a list of FIRST member organizations and their constituencies send an email to docserver@first.org with an empty "subject" line and a message body containing the line "send first-contacts".
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