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AUSCERT External Security Bulletin Redistribution
ESB-1999.170 -- CERT Advisory CA-99-14
Multiple Vulnerabilities in BIND
11 November 1999
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The CERT Coordination Centre has released the following advisory concerning
multiple vulnerabilities in BIND. Remote users may execute arbitrary code
with the privilege of the named daemon or impair normal operation of the
daemon on systems with vulnerable versions of BIND.
Under certain circumstances these vulnerabilities may allow remote users
to gain root access or to perform Denial of Service (DoS) attacks against
vulnerable systems.
These vulnerabilities differ from those previously reported in the DNS
Denial of Service related AusCERT Alert AL-1999.004.
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CERT Advisory CA-99-14 Multiple Vulnerabilities in BIND
Original release date: November 10, 1999
Last revised: --
Source: CERT/CC
A complete revision history is at the end of this file.
Systems Affected
* Systems running various versions of BIND
I. Description
Six vulnerabilities have been found in BIND, the popular domain name
server from the Internet Software Consortium (ISC). One of these
vulnerabilities may allow remote intruders to gain privileged access
to name servers.
Vulnerability #1: the "nxt bug"
Some versions of BIND fail to properly validate NXT records. This
improper validation could allow an intruder to overflow a buffer and
execute arbitrary code with the privileges of the name server.
NXT record support was introduced in BIND version 8.2. Prior versions
of BIND, including 4.x, are not vulnerable to this problem. The
ISC-supplied version of BIND corrected this problem in version 8.2.2.
Vulnerability #2: the "sig bug"
This vulnerability involves a failure to properly validate SIG
records, allowing a remote intruder to crash named; see the impact
section for additional details.
SIG record support is found in multiple versions of BIND, including
4.9.5 through 8.x.
Vulnerability #3: the "so_linger bug"
By intentionally violating the expected protocols for closing a TCP
session, remote intruders can cause named to pause for periods up to
120 seconds.
Vulnerability #4: the "fdmax bug"
Remote intruders can consume more file descriptors than BIND can
properly manage, causing named to crash.
Vulnerability #5: the "maxdname bug"
Improper handling of certain data copied from the network could allow
a remote intruder to disrupt the normal operation of your name server,
possibly including a crash.
Vulnerability #6: the "naptr bug"
Some versions of BIND fail to validate zone information loaded from
disk files. In environments with unusual combinations of permissions
and protections, this could allow an intruder to crash named.
Other recent BIND-related vulnerabilities
AusCERT recently published a report describing denial-of-service
attacks against name servers. These attacks are unrelated to the
issues described in this advisory. For information on the
denial-of-service attacks described by AusCERT, please see AusCERT
Alert AL-1999.004 available at:
ftp://ftp.auscert.org.au/pub/auscert/advisory/AL-1999.004.dns_dos
II. Impact
Vulnerability #1
By exploiting this vulnerability, remote intruders can execute
arbitrary code with the privileges of the user running named,
typically root.
Vulnerabilities #2, #4, and #5
By exploiting these vulnerabilities, remote intruders can disrupt the
normal operation of your name server, possibly causing a crash.
Vulnerability #3
By periodically exercising this vulnerability, remote intruders can
disrupt the ability of your name server to respond to legitimate
queries. By intermittently exercising this vulnerability, intruders
can seriously degrade the performance of your name server.
Vulnerability #6
Local intruders who gain write access to your zone files can cause
named to crash.
III. Solution
Apply a patch from your vendor or update to a later version of BIND
Many operating system vendors distribute BIND with their operating
system. Depending on your support procedures, arrangements, and
contracts, you may wish to obtain BIND from your operating system
vendor rather than directly from ISC.
Appendix A contains information provided by vendors for this advisory.
We will update the appendix as we receive more information. If you do
not see your vendor's name, the CERT/CC did not hear from that vendor.
Please contact your vendor directly.
Appendix A. Vendor Information
Vendor Name
Caldera
See ftp://ftp.calderasystems.com/pub/OpenLinux/updates/2.3/current
MD5s
db1dda05dbe0f67c2bd2e5049096b42c RPMS/bind-8.2.2p3-1.i386.rpm
82bbe025ac091831904c71c885071db1 RPMS/bind-doc-8.2.2p3-1.i386.rpm
2f9a30444046af551eafd8e6238a50c6 RPMS/bind-utils-8.2.2p3-1.i386.rpm
0e4f041549bdd798cb505c82a8911198 SRPMS/bind-8.2.2p3-1.src.rpm
Compaq Computer Corporation
At the time of writing this document, Compaq is currently
investigating the potential impact to Compaq's BIND release(s).
As further information becomes available Compaq will provide notice of
the completion/availability of any necessary patches through AES
services (DIA, DSNlink FLASH and posted to the Services WEB page) and
be available from your normal Compaq Services Support channel.
Data General
We are investigating. We will provide an update when our investigation
is complete.
Hewlett-Packard Company
HP is vulnerable, see the chart in the ISC advisory for details on
your installed version of BIND. Our fix strategy is under
investigation, watch for updates to this CERT advisory in the CERT
archives, or an HP security advisory/bulletin.
IBM Corporation
The bind8 shipped with AIX 4.3.x is vulnerable. We are currently
working on the following APARs which will be available soon:
APAR 4.3.x: IY05851
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.
The Internet Software Consortium
ISC has published an advisory regarding these problems, available at
http://www.isc.org/products/BIND/bind-security-19991108.html
The ISC advisory also includes a table summarizing which versions of
BIND are susceptible to the vulnerabilities described in this
advisory.
OpenBSD
As far as we know, we don't ship with any of those vulnerabilities.
Santa Cruz Operation, Inc
Security patches for the following SCO products will be made available
at http://www.sco.com/security
OpenServer 5.x.x, UnixWare 7.x.x, UnixWare 2.x.x
Sun Microsystems
Vulnerability #1
Solaris 2.3, 2.4, 2.5, 2.5.1, 2.6, and 7 are not vulnerable.
Vulnerability #2
Solaris 2.3, 2.4, 2.5, 2.5.1, 2.6, and 7 are not vulnerable.
Vulnerability #3
Solaris 2.3, 2.4, 2.5, 2.5.1, and 2.6 are not vulnerable.
Sun will be producing patches for Solaris 7.
Vulnerability #4
Solaris 2.3, 2.4, 2.5, 2.5.1, and 2.6 are not vulnerable.
Solaris 7 is probably not vulnerable. We are still
investigating.
Vulnerability #5
Solaris 2.3, 2.4, 2.5, 2.5.1, and 2.6 are not vulnerable.
Sun will be producing patches for Solaris 7.
Vulnerability #6
Solaris 2.3, 2.4, 2.5, 2.5.1, and 2.6 are not vulnerable.
Sun will be producing patches for Solaris 7.
_________________________________________________________________
The CERT Coordination Center would like to thank David Conrad, Paul
Vixie and Bob Halley of the Internet Software Consortium for notifying
us of these problems and for their help in constructing the advisory,
and Olaf Kirch of Caldera for notifying us of some of these problems
and providing technical assistance and advice.
______________________________________________________________________
This document is available from:
http://www.cert.org/advisories/CA-99-14-bind.html
______________________________________________________________________
CERT/CC Contact Information
Email: cert@cert.org
Phone: +1 412-268-7090 (24-hour hotline)
Fax: +1 412-268-6989
Postal address:
CERT Coordination Center
Software Engineering Institute
Carnegie Mellon University
Pittsburgh PA 15213-3890
U.S.A.
CERT personnel answer the hotline 08:00-20:00 EST(GMT-5) / EDT(GMT-4)
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______________________________________________________________________
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_________________________________________________________________
Revision History
November 10, 1999: Initial release
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