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computer vulnerability note CVE-2009-3563

NTP: denial of service

Synthesis of the vulnerability

A remote attacker can send a specially crafted NTP MODE_PRIVATE query in order to generate a denial of service.
Vulnerable software: Avaya Ethernet Routing Switch, Debian, BIG-IP Hardware, TMOS, Fedora, FreeBSD, Tru64 UNIX, HP-UX, AIX, Juniper J-Series, Junos OS, Mandriva Linux, Mandriva NF, Meinberg NTP Server, NetBSD, Nortel ESM, Nortel VPN Router, NLD, OES, NTP.org, OpenSolaris, openSUSE, Solaris, Trusted Solaris, RHEL, Slackware, SLES, ESX, ESXi.
Severity of this announce: 2/4.
Consequences of an intrusion: denial of service on server, denial of service on service.
Attacker's origin: internet client.
Creation date: 09/12/2009.
Références of this computer vulnerability: 025389-01, 1021781, 2009009932, 275590, 6902029, BID-37255, c01961950, c02737553, c03714526, CERTA-2010-AVI-002, CR131466, CVE-2009-3563, DSA-1948-1, FEDORA-2009-13046, FEDORA-2009-13090, FEDORA-2009-13121, FreeBSD-SA-10:02.ntpd, HPSBTU02496, HPSBUX02639, HPSBUX02859, IZ68659, IZ71047, IZ71071, IZ71093, IZ71608, IZ71610, IZ71611, IZ71613, IZ71614, MDVSA-2009:328, NetBSD-SA2010-005, PSN-2009-12-609, RHSA-2009:1648-01, RHSA-2009:1651-01, SOL10905, SSA:2009-343-01, SSRT090245, SSRT100293, SSRT101144, SUSE-SR:2009:020, VIGILANCE-VUL-9259, VMSA-2010-0004, VMSA-2010-0004.1, VMSA-2010-0004.2, VMSA-2010-0004.3, VMSA-2010-0009, VMSA-2010-0009.1.

Description of the vulnerability

The NTP protocol possess multiple modes of operation.

The MODE_PRIVATE mode is used by ntpdc to query the state of ntpd daemon. When ntpd receives an invalid MODE_PRIVATE request, it sends back a MODE_PRIVATE error. However, when ntpd receives a MODE_PRIVATE error, it sends it back to the sender generating a loop.

A remote attacker can therefore send a specially crafted NTP MODE_PRIVATE query in order to generate a denial of service.
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