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.
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.
Exploitable: From adjacent networks
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.
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).
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
Japanese Translation: [planned]
Spanish Translation: [planned]
German Translation: [planned]
Portugese Translation: [planned]
If you'd like more information on ISC Subscription Support and Advance Security Notifications, please visit https://www.isc.org/support/.
Do you still have questions? Questions regarding this advisory should go to email@example.com. To report a new issue, please encrypt your message using firstname.lastname@example.org's PGP key which can be found here: https://www.isc.org/downloads/software-support-policy/openpgp-key/. If you are unable to use encrypted email, you may also report new issues at: https://www.isc.org/community/report-bug/.
Note: ISC patches only currently supported versions. When possible, we indicate EOL versions affected. (For current information on which versions are actively supported, please see https://www.isc.org/downloads/.)
ISC Security Vulnerability Disclosure Policy: Details of our current security advisory policy and practice can be found in the ISC Software Defect and Security Vulnerability Disclosure Policy.
This Knowledgebase article is the complete and official security advisory document.
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.