Cisco Security Advisory
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AV:N/AC:M/Au:N/C:N/I:P/A:N/E:U/RL:OF/RC:C
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A vulnerability in ntpd could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition on an affected system.
The vulnerability is due to improper processing of Network Time Protocol (NTP) packets when handling symmetric key authentication failures. An attacker could exploit this vulnerability by conducting a man-in-the-middle attack to periodically transmit crafted NTP packets with set NTP state variables. An exploit could allow the attacker to disrupt communication between NTP hosts, preventing synchronization and leading to a DoS condition for legitimate users.
NTP.org has confirmed this vulnerability in a security advisory and released software updates.
To exploit this vulnerability, an attacker may require access to trusted, internal networks to send crafted requests to the affected software. This access requirement could limit the likelihood of a successful exploit.
An attacker may attempt to perform a man-in-the-middle attack to send crafted packets to the targeted device in an attempt to exploit this vulnerability.
Reports indicate that systems that are configured to use the symmetric key authentication mechanism are affected.
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NTP.org has released a security notice for bug ID Sec 2781 at the following link: CVE-2015-1799
Cisco has released a security advisory for bug IDs CSCut77422 and CSCut77471 at the following link: cisco-sa-20150408-ntpd
ICS-CERT has released a vulnerability note at the following link: CVE-2015-1799
Apple has released a security advisory at the following link: HT204942
FreeBSD has released a VuXML document at the following link: Multiple vulnerabilities of ntp
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 1199435 at the following links: CVE-2015-1799 and RHSA-2015-1459
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Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only privileged users to access administration or management systems.
Administrators are advised to implement an intrusion prevention system (IPS) or intrusion detection system (IDS) to help detect and prevent attacks that attempt to exploit this vulnerability.
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 symmetric mode packet processing denial of service vulnerability. NA Final 2015-Jul-01 2.0 HP has released a security bulletin and updated software to address the Network Time Protocol daemon symmetric mode packet processing denial of service vulnerability. NA Final 2015-May-21
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