(Red Hat Issues Fix) ntp Multiple Flaws Let Remote Users Spoof Messages, Obtain Potentially Sensitive Information, and Deny Service
SecurityTracker Alert ID: 1036522|
SecurityTracker URL: http://securitytracker.com/id/1036522
(Links to External Site)
Date: Aug 3 2016
Denial of service via network, Disclosure of system information, Disclosure of user information, Modification of user information|
Fix Available: Yes Vendor Confirmed: Yes |
Version(s): prior to 4.2.8p6|
Multiple vulnerabilities were reported in ntp. A remote user can cause denial of service conditions on the target system. A remote user can obtain potentially sensitive information on the target system. A remote user can impersonate ntp peers.|
A remote user can conduct a replay attack against authenticated broadcast mode packets [CVE-2015-7973].
A remote authenticated user can exploit a key check flaw to impersonate a peer [CVE-2015-7974].
A remote user can send specially crafted data to trigger a buffer overflow in the nextvar() function in ntpq and cause the target service to crash [CVE-2015-7975].
A remote authenticated user can send an ntpq saveconfig command with specially crafted filename characters to cause unintended results [CVE-2015-7976].
A remote user can send a specially crafted ntpdc reslist command to trigger a null pointer dereference and cause the target service to crash [CVE-2015-7977].
A remote user can send a specially crafted reslist command to consume all available stack memory [CVE-2015-7978].
A remote user can send a specially crafted broadcast mode packet to cause the target broadcast client to tear down the association with the broadcast server [CVE-2015-7979].
A remote server can send a specially crafted packet with an origin timestamp of zero to bypass the timestamp validation check in certain cases [CVE-2015-8138].
A remote user can send specially crafted data to trigger an infinite loop in ntpq [CVE-2015-8158].
A remote user can trigger an origin leak in ntpq and ntpdc to obtain potentially sensitive information [CVE-2015-8139].
A remote user on the local network may be able to conduct replay attacks against ntpq [CVE-2015-8140].
Cisco ASIG reported these vulnerabilities.
A remote user can cause denial of service conditions.|
A remote user can obtain potentially sensitive information on the target system.
A remote authenticated user can impersonate an ntp peer.
Red Hat has issued a fix for CVE-2015-7979.|
The Red Hat advisory is available at:
Vendor URL: rhn.redhat.com/errata/RHSA-2016-1552.html (Links to External Site)
Access control error, Authentication error, Boundary error|
|Underlying OS: Linux (Red Hat Enterprise)|
|Underlying OS Comments: 6.7|
This archive entry is a follow-up to the message listed below.|
Source Message Contents
Subject: [RHSA-2016:1552-01] Moderate: ntp security update|
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Red Hat Security Advisory
Synopsis: Moderate: ntp security update
Advisory ID: RHSA-2016:1552-01
Product: Red Hat Enterprise Linux
Advisory URL: https://rhn.redhat.com/errata/RHSA-2016-1552.html
Issue date: 2016-08-03
CVE Names: CVE-2015-7979 CVE-2016-1547 CVE-2016-1548
An update for ntp is now available for Red Hat Enterprise Linux 6.7
Extended Update Support.
Red Hat Product Security has rated this update as having a security impact
of Moderate. A Common Vulnerability Scoring System (CVSS) base score, which
gives a detailed severity rating, is available for each vulnerability from
the CVE link(s) in the References section.
2. Relevant releases/architectures:
Red Hat Enterprise Linux HPC Node EUS (v. 6.7) - x86_64
Red Hat Enterprise Linux HPC Node Optional EUS (v. 6.7) - noarch, x86_64
Red Hat Enterprise Linux Server EUS (v. 6.7) - i386, ppc64, s390x, x86_64
Red Hat Enterprise Linux Server Optional EUS (v. 6.7) - i386, noarch, ppc64, s390x, x86_64
The Network Time Protocol (NTP) is used to synchronize a computer's time
with another referenced time source. These packages include the ntpd
service which continuously adjusts system time and utilities used to query
and configure the ntpd service.
* It was found that when NTP was configured in broadcast mode, a remote
attacker could broadcast packets with bad authentication to all clients.
The clients, upon receiving the malformed packets, would break the
association with the broadcast server, causing them to become out of sync
over a longer period of time. (CVE-2015-7979)
* A denial of service flaw was found in the way NTP handled preemptable
client associations. A remote attacker could send several crypto NAK
packets to a victim client, each with a spoofed source address of an
existing associated peer, preventing that client from synchronizing its
* It was found that an ntpd client could be forced to change from basic
client/server mode to the interleaved symmetric mode. A remote attacker
could use a spoofed packet that, when processed by an ntpd client, would
cause that client to reject all future legitimate server responses,
effectively disabling time synchronization on that client. (CVE-2016-1548)
* A flaw was found in the way NTP's libntp performed message
authentication. An attacker able to observe the timing of the comparison
function used in packet authentication could potentially use this flaw to
recover the message digest. (CVE-2016-1550)
* An out-of-bounds access flaw was found in the way ntpd processed certain
packets. An authenticated attacker could use a crafted packet to create a
peer association with hmode of 7 and larger, which could potentially
(although highly unlikely) cause ntpd to crash. (CVE-2016-2518)
The CVE-2016-1548 issue was discovered by Miroslav Lichvar (Red Hat).
For details on how to apply this update, which includes the changes
described in this advisory, refer to:
After installing this update, the ntpd daemon will restart automatically.
5. Bugs fixed (https://bugzilla.redhat.com/):
1300271 - CVE-2015-7979 ntp: off-path denial of service on authenticated broadcast mode
1331461 - CVE-2016-1547 ntp: crypto-NAK preemptable association denial of service
1331462 - CVE-2016-1548 ntp: ntpd switching to interleaved mode with spoofed packets
1331464 - CVE-2016-1550 ntp: libntp message digest disclosure
1331468 - CVE-2016-2518 ntp: out-of-bounds references on crafted packet
6. Package List:
Red Hat Enterprise Linux HPC Node EUS (v. 6.7):
Red Hat Enterprise Linux HPC Node Optional EUS (v. 6.7):
Red Hat Enterprise Linux Server EUS (v. 6.7):
Red Hat Enterprise Linux Server Optional EUS (v. 6.7):
These packages are GPG signed by Red Hat for security. Our key and
details on how to verify the signature are available from
The Red Hat security contact is <email@example.com>. More contact
details at https://access.redhat.com/security/team/contact/
Copyright 2016 Red Hat, Inc.
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