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vulnerability note CVE-2013-5211

ntp.org: distributed denial of service via monlist

Synthesis of the vulnerability

An attacker can use monlist of ntp.org, in order to trigger a distributed denial of service.
Vulnerable products: GAiA, CheckPoint IP Appliance, IPSO, Provider-1, CheckPoint Security Appliance, CheckPoint Security Gateway, Cisco ASR, Cisco Catalyst, IOS by Cisco, IOS XE Cisco, IOS XR Cisco, Nexus by Cisco, NX-OS, Cisco Router, Cisco CUCM, Cisco Unified CCX, Cisco MeetingPlace, FreeBSD, HP-UX, AIX, Juniper J-Series, Junos OS, Meinberg NTP Server, NetBSD, NTP.org, openSUSE, Solaris, Trusted Solaris, pfSense, Puppet, Slackware, ESX, ESXi, vCenter Server, VMware vSphere, VMware vSphere Hypervisor.
Severity of this weakness: 2/4.
Consequences of an attack: denial of service on service.
Hacker's origin: internet client.
Creation date: 31/12/2013.
Références of this bulletin: 1532, BID-64692, c04084148, CERTA-2014-AVI-034, CERTFR-2014-AVI-069, CERTFR-2014-AVI-112, CERTFR-2014-AVI-117, CERTFR-2014-AVI-244, CERTFR-2014-AVI-526, CSCtd75033, CSCum44673, CSCum52148, CSCum76937, CSCun84909, CSCur38341, CVE-2013-5211, ESX400-201404001, ESX400-201404402-SG, ESX410-201404001, ESX410-201404402-SG, ESXi400-201404001, ESXi400-201404401-SG, ESXi410-201404001, ESXi410-201404401-SG, ESXi510-201404001, ESXi510-201404101-SG, ESXi510-201404102-SG, ESXi550-201403101-SG, FreeBSD-SA-14:02.ntpd, HPSBUX02960, JSA10613, MBGSA-1401, NetBSD-SA2014-002, openSUSE-SU-2014:0949-1, openSUSE-SU-2014:1149-1, sk98758, SSA:2014-044-02, SSRT101419, VIGILANCE-VUL-14004, VMSA-2014-0002, VMSA-2014-0002.1, VMSA-2014-0002.2, VMSA-2014-0002.4, VMSA-2015-0001.

Description of the vulnerability

The ntp.org service implements the "monlist" command, which returns the list of the 600 last clients which connected to the server.

However, the size of the reply is larger than the size of the query. Moreover, public NTP servers request no authentication, and UDP packets can be spoofed.

An attacker can therefore use monlist of ntp.org, in order to trigger a distributed denial of service.
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