Scientific Linux Security Update : ntp on SL7.x x86_64

This script is Copyright (C) 2015 Tenable Network Security, Inc.

Synopsis :

The remote Scientific Linux host is missing one or more security

Description :

It was found that because NTP's access control was based on a source
IP address, an attacker could bypass source IP restrictions and send
malicious control and configuration packets by spoofing ::1 addresses.
(CVE-2014-9298, CVE-2014-9751)

A denial of service flaw was found in the way NTP hosts that were
peering with each other authenticated themselves before updating their
internal state variables. An attacker could send packets to one peer
host, which could cascade to other peers, and stop the synchronization
process among the reached peers. (CVE-2015-1799)

A flaw was found in the way the ntp-keygen utility generated MD5
symmetric keys on big-endian systems. An attacker could possibly use
this flaw to guess generated MD5 keys, which could then be used to
spoof an NTP client or server. (CVE-2015-3405)

A stack-based buffer overflow was found in the way the NTP autokey
protocol was implemented. When an NTP client decrypted a secret
received from an NTP server, it could cause that client to crash.
(CVE-2014-9297, CVE-2014-9750)

It was found that ntpd did not check whether a Message Authentication
Code (MAC) was present in a received packet when ntpd was configured
to use symmetric cryptographic keys. A man-in-the-middle attacker
could use this flaw to send crafted packets that would be accepted by
a client or a peer without the attacker knowing the symmetric key.

Bug fixes :

- The ntpd service truncated symmetric keys specified in
the key file to 20 bytes. As a consequence, it was
impossible to configure NTP authentication to work with
peers that use longer keys. With this update, the
maximum key length has been changed to 32 bytes.

- The ntpd service could previously join multicast groups
only when starting, which caused problems if ntpd was
started during system boot before network was
configured. With this update, ntpd attempts to join
multicast groups every time network configuration is

- Previously, the ntp-keygen utility used the exponent of
3 when generating RSA keys. Consequently, generating RSA
keys failed when FIPS mode was enabled. With this
update, ntp-keygen has been modified to use the exponent
of 65537, and generating keys in FIPS mode now works as

- The ntpd service dropped incoming NTP packets if their
source port was lower than 123 (the NTP port). With this
update, ntpd no longer checks the source port number,
and clients behind NAT are now able to correctly
synchronize with the server.

Enhancements :

- This update adds support for configurable Differentiated
Services Code Points (DSCP) in NTP packets, simplifying
configuration in large networks where different NTP
implementations or versions are using different DSCP

- This update adds the ability to configure separate clock
stepping thresholds for each direction (backward and
forward). Use the 'stepback' and 'stepfwd' options to
configure each threshold.

- Support for nanosecond resolution has been added to the
Structural Health Monitoring (SHM) reference clock.
Prior to this update, when a Precision Time Protocol
(PTP) hardware clock was used as a time source to
synchronize the system clock, the accuracy of the
synchronization was limited due to the microsecond
resolution of the SHM protocol. The nanosecond extension
in the SHM protocol now allows sub-microsecond
synchronization of the system clock.

See also :

Solution :

Update the affected packages.

Risk factor :

Medium / CVSS Base Score : 6.8

Family: Scientific Linux Local Security Checks

Nessus Plugin ID: 87564 ()

Bugtraq ID:

CVE ID: CVE-2014-9297

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