Cisco Security Advisory
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A vulnerability in the Network Time Protocol (NTP) daemon could allow an unauthenticated, adjacent attacker to bypass authentication mechanisms and access an affected system.
The vulnerability is due to incorrect validation of the message authentication code (MAC) field. An attacker could exploit this vulnerability by sending unauthenticated NTP packets to an NTP host that is configured with symmetric key authentication. An exploit could allow the attacker to inject NTP packets to the NTP host without knowing the NTP symmetric key.
NTP.org has released a security notice and software updates to address the vulnerability.
To exploit the vulnerability, the attacker may need access to trusted or internal networks to transmit crafted packets to the affected system. This access requirement limits the likelihood of a successful exploit.
The vulnerability is exploitable only on an application that is configured with the symmetric key authentication mechanism. Authentication using autokey is not affected.
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NTP.org has released a security notice at the following link: April 2015 NTP Security Vulnerability Announcement
Cisco has released a security advisory for bug IDs CSCut77422 and CSCut77471 at the following link: cisco-sa-20150408-ntpd
Apple has released a security advisory at the following link: HT204942
ICS-CERT has released a vulnerability note at the following link: VU#374268
FreeBSD has released a VuXML document at the following link: CVE-2015-1798
HP has released a security bulletin c04679309 at the following link: HPSBUX03333 SSRT102029
Red Hat has released an official CVE statement and a security advisory for bug 1199430 at the following links: CVE-2015-1798 and RHSA-2015-1459
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Administrators are advised to apply the appropriate updates.
Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
Administrators are advised to monitor affected systems.
The Cisco Applied Intelligence team has created the following companion document to guide administrators in identifying and mitigating attempts to exploit this vulnerability prior to applying updated software: Identifying and Mitigating Multiple Vulnerabilities in Network Time Protocol
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NTP.org has released software updates at the following link: ntp 4.2.8p2 or later
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via email at tac@cisco.com
Apple has released updated software at the following links: OS X Yosemite 10.10.4
FreeBSD releases ports collection updates at the following link: Ports Collection Index
HP has released updated software for customers as described in the "Resolution" section of the security bulletin.
Red Hat has released updated software for registered subscribers at the following link: Red Hat Network. Red Hat packages can be updated on Red Hat Enterprise Linux versions 5 and later using the yum tool.
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The Cisco Product Security Incident Response Team (PSIRT) is not aware of any public announcements or malicious use of the vulnerability that is described in this advisory.
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To learn about Cisco security vulnerability disclosure policies and publications, see the Security Vulnerability Policy. This document also contains instructions for obtaining fixed software and receiving security vulnerability information from Cisco.
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Show LessVersion Description Section Status Date 3.0 Apple has released a security advisory and updated software to address the Network Time Protocol daemon MAC checking failure authentication bypass vulnerability. NA Final 2015-Jul-01 2.0 HP has released a security bulletin and updated software to address the Network Time Protocol daemon MAC checking failure authentication bypass vulnerability. NA Final 2015-May-21
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