[TriLUG] CERT Advisory on ISC DHCPD Minries

Thu Jan 16 09:51:43 EST 2003

Got this from CERT. ISC DHCPD is vulnerable. There are only 2 "popular" distros that are affect that we talk about here. (something is just not right with that sentence). Anyway, It appears that RHL 8.0 (not other versions) and SUSE are affected (NOT Mandrake).

HTH

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CERT Advisory CA-2003-01 Buffer Overflows in ISC DHCPD Minires Library

Original release date: January 15, 2003

Last revised: --

Source: CERT/CC

A complete revision history can be found at the end of this file.

Systems Affected

* Systems running ISC DHCPD versions 3.0 through 3.0.1RC10,

inclusive.

* For detailed vendor status information, see

http://www.kb.cert.org/vuls/id/284857#systems

Overview

The Internet Software Consortium (ISC) has discovered several buffer

overflow vulnerabilities in their implementation of DHCP (ISC DHCPD).

These vulnerabilities may allow remote attackers to execute arbitrary

code on affected systems. At this time, we are not aware of any

exploits.

I. Description

There are multiple remote buffer overflow vulnerabilities in the ISC

implementation of DHCP. As described in RFC 2131, "the Dynamic Host

Configuration Protocol (DHCP) provides a framework for passing

configuration information to hosts on a TCP/IP network." In addition to

supplying hosts with network configuration data, ISC DHCPD allows the

DHCP server to dynamically update a DNS server, eliminating the need

for manual updates to the name server configuration. Support for

dynamic DNS updates is provided by the NSUPDATE feature.

During an internal source code audit, developers from the ISC

discovered several vulnerabilities in the error handling routines of

the minires library, which is used by NSUPDATE to resolve hostnames.

These vulnerabilities are stack-based buffer overflows that may be

exploitable by sending a DHCP message containing a large hostname

value. Note: Although the minires library is derived from the BIND 8

resolver library, these vulnerabilities do not affect any current

versions of BIND.

The CERT/CC is tracking this issue as VU#284857. This reference number

corresponds to CVE candidate CAN-2003-0026.

II. Impact

Remote attackers may be able to execute arbitrary code with the

privileges of the user running ISC DHCPD.

III. Solution

Upgrade or apply a patch

The ISC has addressed these vulnerabilities in versions 3.0pl2 and

3.0.1RC11 of ISC DHCPD. If your software vendor supplies ISC DHCPD as

part of an operating system distribution, please see Appendix A for

vendor-specific patch information.

For a detailed list of vendors that have been notified of this issue by

the CERT/CC, please see

http://www.kb.cert.org/vuls/id/284857#systems

Disable dynamic DNS updates (NSUPDATE)

As an interim measure, the ISC recommends disabling the NSUPDATE

feature on affected DHCP servers.

Block external access to DHCP server ports

As an interim measure, it is possible to limit exposure to these

vulnerabilities by restricting external access to affected DHCP servers

on the following ports:

bootps 67/tcp # Bootstrap Protocol Server

bootps 67/udp # Bootstrap Protocol Server

bootpc 68/tcp # Bootstrap Protocol Client

bootpc 68/udp # Bootstrap Protocol Client

Disable the DHCP service

As a general rule, the CERT/CC recommends disabling any service or

capability that is not explicitly required. Depending on your network

configuration, you may not need to use DHCP.

Appendix A. - Vendor Information

This appendix contains information provided by vendors for this

advisory. As vendors report new information to the CERT/CC, we will

update this section and note the changes in our revision history. If a

particular vendor is not listed below, we have not received their

comments.

Apple Computer, Inc.

Mac OS X and Mac OS X Server do not contain the vulnerability described

in this notice.

Berkeley Software Design, Inc. (BSDI)

This vulnerability is addressed by the M431-001 and M500-004 patches

for the 4.3.1 and 5.0 versions of BSD/OS.

Cisco Systems

No Cisco products have been found to be affected by this vulnerability.

Several Cisco products do utilize the ISC DHCPD, however, no Cisco

products implement the ISC DHCPD NSUPDATE feature, nor do they include

the minires library.

Cray Inc.

Cray Inc. is not vulnerable as dhcpd is not supported on any of its

products.

Fujitsu

Fujitsu's UXP/V OS is not vulnerable because it does not support the

ISC DHCPD.

Hewlett-Packard Company

Source: Hewlett-Packard Company

Software Security Response Team

cross reference id: SSRT2423

HP-UX - not vulnerable

HP-MPE/ix - not vulnerable

HP Tru64 UNIX - not vulnerable

HP OpenVMS - not vulnerable

HP NonStop Servers - not vulnerable

To report potential security vulnerabilities in HP software,

send an E-mail message to: mailto:security-alert at hp.com

Hitachi, Ltd.

We've checked up on our router (Hitachi,Ltd. GR2000 series) about

[VU#284857]. Our DHCP implementation is NOT vulnerable.

IBM Corporation

IBM's AIX does not ship with the ISC DHCP daemon. The issues discussed

in VU#284857 or any following advisories based on this vulnerability

note do not pertain to AIX.

Internet Software Consortium

We have a patched version of 3.0 available (3.0pl2) and a new release

candidate for the next bug-fix release (3.0.1RC11). Both of these new

releases are available from http://www.isc.org/products/DHCP/.

MontaVista Software

None of MontaVista Software's Linux products are vulnerable to this

issue.

NEC Inc.

[Server Products]

* EWS/UP 48 Series operating system

- is NOT vulnerable.

NetBSD

Currently supported versions of NetBSD do not contain the error

handling routine vulnerabilities. Such vulnerabilities were fixed

prior to the release of NetBSD 1.5.

With respect to the patch to ns_name.c, we believe that this is good

defensive programming and have applied the patch to NetBSD-current.

However, all calls to ns_name_ntol in the NetBSD source base pass a

correct, constant, non-zero value as the datsiz parameter.

Therefore, NetBSD is not vulnerable.

NetScreen

NetScreen is not vulnerable to this issue.

OpenBSD

OpenBSD's dhcp support is much modified, does not have that feature,

and therefore does not have that bug.

Openwall GNU/*/Linux

Openwall GNU/*/Linux is not vulnerable. We don't yet provide a DHCP

suite.

Red Hat Inc.

Red Hat distributes a vulnerable version of ISC DHCP in Red Hat Linux

8.0. Other distributions of Red Hat Linux are not vulnerable to these

issues. New DHCP packages are available along with our advisory at the

URL below. Users of the Red Hat Network can update their systems using

the 'up2date' tool.

http://rhn.redhat.com/errata/RHSA-2003-011.html

Riverstone Networks

Riverstone Networks is not vulnerable to VU#284857.

Sun Microsystems, Inc.

Sun confirms that we are not vulnerable to the issues described in

VU#284857. Solaris does not ship the ISC DHCPD and does not use any of

the ISC DHCPD source in its version of DHCPD.

SuSE Linux AG

We are preparing updates, that will be released soon.

Xerox

Xerox is aware of this vulnerability and is currently assessing all

products. This statement will be updated as new information becomes

available.

_________________________________________________________________

The CERT Coordination Center thanks David Hankins of the Internet

Software Consortium for notifying us about this problem and for helping

us to construct this document. We also thank Jacques A. Vidrine for

drawing attention to this issue.

_________________________________________________________________

Author: This document was written by Jeffrey P. Lanza.

______________________________________________________________________

This document is available from:

http://www.cert.org/advisories/CA-2003-01.html

______________________________________________________________________

CERT/CC Contact Information

Email: cert at 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/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) /

EDT(GMT-4) Monday through Friday; they are on call for emergencies

during other hours, on U.S. holidays, and on weekends.

Using encryption

We strongly urge you to encrypt sensitive information sent by email.

Our public PGP key is available from

http://www.cert.org/CERT_PGP.key

If you prefer to use DES, please call the CERT hotline for more

information.

Getting security information

CERT publications and other security information are available from

our web site

http://www.cert.org/

To subscribe to the CERT mailing list for advisories and bulletins,

send email to majordomo at cert.org. Please include in the body of your

message

subscribe cert-advisory

* "CERT" and "CERT Coordination Center" are registered in the U.S.

Patent and Trademark Office.

______________________________________________________________________

NO WARRANTY

Any material furnished by Carnegie Mellon University and the Software

Engineering Institute is furnished on an "as is" basis. Carnegie

Mellon University makes no warranties of any kind, either expressed or

implied as to any matter including, but not limited to, warranty of

fitness for a particular purpose or merchantability, exclusivity or

results obtained from use of the material. Carnegie Mellon University

does not make any warranty of any kind with respect to freedom from

patent, trademark, or copyright infringement.

_________________________________________________________________

Conditions for use, disclaimers, and sponsorship information

Revision History

January 15, 2003: Initial release

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