-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

===========================================================================
             AUSCERT External Security Bulletin Redistribution

                               ESB-2013.0451
           CVE-2013-2494: A Vulnerability in libdns Could Cause
                   Excessive Memory Use in ISC DHCP 4.2
                               2 April 2013

===========================================================================

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           DHCP
Operating System:  UNIX variants (UNIX, Linux, OSX)
                   Windows
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2013-2494  

Original Bulletin: 
   https://kb.isc.org/article/AA-00880/

- --------------------------BEGIN INCLUDED TEXT--------------------

CVE-2013-2494: A Vulnerability in libdns Could Cause Excessive Memory Use in 
ISC DHCP 4.2

A memory exhaustion bug has been discovered in libdns, which is used by ISC 
DHCP 4.2. Theoretically this could be exploited to cause memory exhaustion in
ISC DHCP 4.2.

CVE: 			CVE-2013-2494
Document Version:       2.0
Posting date: 		26 March 2013
Program Impacted: 	ISC DHCP
Versions affected: 	4.2.0 -> 4.2.5.  ISC DHCP versions prior to 4.2.0 
			(including 4.1-ESV) are not affected.
Severity: 		Low
Exploitable: 		From adjacent networks

Description:

Exploitation of a memory exhaustion bug in libdns is theoretically possible in
ISC DHCP 4.2, which uses the library from BIND 9 for Dynamic DNS.

Unlike vulnerabilities which can be exercised by a machine impersonating a 
malicious client, exploitation of this vulnerability is complex and requires 
either controlling a nameserver with whom the DHCP server process is 
communicating or successfully spoofing traffic to appear as such. These 
preconditions result in a CVSS severity of "Low", but operators using 
vulnerable versions of DHCP 4.2 are nevertheless recommended to upgrade to 
DHCP 4.2.5-P1, which prevents exploitation of the libdns library defect.

Impact:

Servers which are targeted by a successful attack will exhaust all memory 
available to the server process, which is likely to crash the DHCP server and
may affect other processes running on the same physical machine when system 
memory is exhausted.

CVSS Score:  		4.9

CVSS Equation:  	(AV:N/AC:H/Au:S/C:N/I:N/A:C)

For more information on the Common Vulnerability Scoring System and to obtain
your specific environmental score please visit: 
http://nvd.nist.gov/cvss.cfm?calculator&adv&version=2&vector=(AV:N/AC:H/Au:S/C:N/I:N/A:C)

Workarounds:

None.  (Or do we want to mention that you can change the build process for 
the BIND libraries?)

Active exploits:

No known active exploits.

Solution:  Upgrade to DHCP 4.2.5-P1

Document Revision History:

1.0 Phase One - Advance Notification, 18 March 2013

1.2 Phase Two & Three Notification, 25 March 2013

2.0 Public notification, 26 March 2013

Related Documents:

Japanese Translation:  [planned]
Spanish Translation:  [planned]
German Translation:  [planned]
Portugese Translation:  [planned]

If you'd like more information on our Forum or product support please visit 
www.isc.org/support.

Do you still have questions?  Questions regarding this advisory should go to 
security-officer@isc.org

Note: ISC patches only currently supported versions. When possible we indicate
EOL versions affected.

ISC Security Vulnerability Disclosure Policy:  Details of our current security 
advisory policy and practice can be found here: 
https://www.isc.org/security-vulnerability-disclosure-policy

This Knowledge Base article https://kb.isc.org/article/AA-00880 is the complete 
and official security advisory document.

Legal Disclaimer:
Internet Systems Consortium (ISC) is providing this notice on an "AS IS" basis.
No warranty or guarantee of any kind is expressed in this notice and none should
be implied. ISC expressly excludes and disclaims any warranties regarding this 
notice or materials referred to in this notice, including, without limitation, 
any implied warranty of merchantability, fitness for a particular purpose, 
absence of hidden defects, or of non-infringement. Your use or reliance on this
notice or materials referred to in this notice is at your own risk. ISC may 
change this notice at any time.  A stand-alone copy or paraphrase of the text 
of this document that omits the document URL is an uncontrolled copy. 
Uncontrolled copies may lack important information, be out of date, or contain 
factual errors.

© 2001-2013 Internet Systems Consortium

- --------------------------END INCLUDED TEXT--------------------

You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.

NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:

        http://www.auscert.org.au/render.html?cid=1980

===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
===========================================================================
-----BEGIN PGP SIGNATURE-----
Comment: http://www.auscert.org.au/render.html?it=1967

iQIVAwUBUVoxeu4yVqjM2NGpAQJjbg/+OnwQ6Yp94F8+E7cPEmhFLFSOJYeWhbR9
nQCRy9GkfZmJ8UhlW7nKgFj6SlyNQb9knMq6Wdh3jtcB0SQOl4QC8Vs8FdACmT+O
zPrlFFgcI+okXkk7te0ZLZAUX/AFIanvnuJJASbxyS/4fUjw4zWfJBRIq4SY0ad4
wEYA7FnX/F+emf3Xx/Xvosx35+grzynNTEmwgeMucmY45WCslJOqqjxrqjbRW771
SlNlDTbTSCrTisAnqaq6xxMEeACakaioP0l6tgIxzz8KGSPKu++GlfK6zrsSOBfr
lIko6uqEZx6F28B/tXgG2TtJ+0Vb9hQPkgm41DZMZALKqIDaEbZUcE1YiOpuVQZB
9iiAaCX9PcY9lULFyx8qlqfUqu6cigZN4DwVkgtXVDcF7rjcvi1WhIvEzQlJTga4
PbljSC8W2h2LJZaSFwatLP1xXpZZJUHJ07rTwmMS10RgpqtJyQPDINgdBqUClF+V
py5adpMt7/ha81Mp6R1ppiuqKAXsDAqQVW1kS3by2j8xTS/prXtggT4nAoEbVb/r
41BK3lIc2kSolJgO+mEVDYjGQeBHKVCSfQOJlbBrTohQcAArYaW3BDO4Bu61zUkR
IDfKCX6GS8HxqTGVmI4ypiNoK9RfHBi9E4azqpRT0prYxvA0PFMPdzg9z7tX5SF/
ZLJAswPg818=
=Vaxk
-----END PGP SIGNATURE-----