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AUSCERT External Security Bulletin Redistribution
ESB-2016.0092
CVE-2015-8605: UDP payload length not properly checked
14 January 2016
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AusCERT Security Bulletin Summary
---------------------------------
Product: DHCP
Publisher: ISC
Operating System: Windows
UNIX variants (UNIX, Linux, OSX)
Impact/Access: Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2015-8605
Original Bulletin:
https://kb.isc.org/article/AA-01334/0/CVE-2015-8605%3A-UDP-payload-length-not-properly-checked.html
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CVE-2015-8605: UDP payload length not properly checked
Author:
Brian Conry
Reference Number:
AA-01334
Views:
4346
Created:
2016-01-12 14:41
Last Updated:
2016-01-12 21:45
CVE:
CVE-2015-8605
Document Version:
2.0
Posting date:
12 January 2016
Program Impacted:
DHCP
Versions affected:
4.0.x, 4.1.x, 4.2.x, 4.1-ESV -> 4.1-ESV-R12, 4.3.0->4.3.3. 3.x may also be
affected but has not been tested.
Severity:
Medium
Exploitable:
- From adjacent networks 2001-2015 Internet Systems Consortium
Description:
A badly formed packet with an invalid IPv4 UDP length field can cause a DHCP
server, client, or relay program to terminate abnormally.
Impact:
Nearly all IPv4 DHCP clients and relays, and most IPv4 DHCP servers are
potentially affected.
A server, client, or relay that is built to only be able to process unicast
packets (i.e. those that have already been processed by the OS UDP/IP stack)
is not affected, however this build configuration is not normally viable for
clients and relays. Servers with this build configuration require a relay in
order to be able to process DISCOVER and other broadcast requests from
clients.
Not all potentially-affected builds will actually be affected, but because it
is difficult to identify or predict those which should be upgraded, our advice
is that all builds should be considered vulnerable.
CVSS Score: 5.7
CVSS Vector: (AV:A/AC:M/Au:N/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:A/AC:M/Au:N/C:N/I:N/A:C)
Workarounds:
None likely, but in some environments following the advice from
https://kb.isc.org/article/AA-00573/31/Securing-Your-Network-From-DHCP-Risks.html
can substantially reduce the risk by limiting the exposure of a DHCP server to
"controlled" networks and clients.
Active exploits:
No known active exploits.
Solution: Upgrade to the patched release most closely related to your current
version of DHCP. These can all be downloaded from
http://www.isc.org/downloads.
DHCP version 4.1-ESV-R12-P1
DHCP version 4.3.3-P1
Acknowledgements: Thanks to Sebastian Poehn from Sophos for reporting this
issue.
Document Revision History:
1.0 Advance Notification 5 January, 2016
1.1 ESV Version name corrected 12 January 2016
2.0 Public Disclosure 12 January, 2016
Related Documents:
If you'd like more information on ISC Subscription Support and Advance
Security Notifications, please visit http://www.isc.org/support/.
Do you still have questions? Questions regarding this advisory should go to
security-officer@isc.org. To report a new issue, please encrypt your message
using security-officer@isc.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 http://www.isc.org/downloads/).
ISC Security Vulnerability Disclosure Policy: Details of our current security
advisory policy and practice can be found here:
https://kb.isc.org/article/AA-00861/164/ISC-Software-Defect-and-Security-Vulnerability-Disclosure-Policy.html
This Knowledge Base article https://kb.isc.org/article/AA-01334 is the
complete and official security advisory document.
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