Scientific Linux Security Update : ntp on SL6.x i386/x86_64

This script is Copyright (C) 2015-2017 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.

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.

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.

The CVE-2015-1798 and CVE-2015-1799 issues were discovered by Miroslav
Lichvr of Red Hat.

Bug fixes :

- The ntpd daemon 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. The maximum length of keys
has now been changed to 32 bytes.

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

- The ntpd daemon included a root delay when calculating
its root dispersion. Consequently, the NTP server
reported larger root dispersion than it should have and
clients could reject the source when its distance
reached the maximum synchronization distance (1.5
seconds by default). Calculation of root dispersion has
been fixed, the root dispersion is now reported
correctly, and clients no longer reject the server due
to a large synchronization distance.

- The ntpd daemon dropped incoming NTP packets if their
source port was lower than 123 (the NTP port). Clients
behind Network Address Translation (NAT) were unable to
synchronize with the server if their source port was
translated to ports below 123. With this update, ntpd no
longer checks the source port number.

Enhancements :

- This update introduces configurable access of memory
segments used for Shared Memory Driver (SHM) reference
clocks. Previously, only the first two memory segments
were created with owner-only access, allowing just two
SHM reference clocks to be used securely on a system.
Now, the owner-only access to SHM is configurable with
the 'mode' option, and it is therefore possible to use
more SHM reference clocks securely.

- Support for nanosecond resolution has been added to the
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 (for
example, with the timemaster service from the linuxptp
package), the accuracy of the synchronization was
limited due to the microsecond resolution of the SHM
protocol. The nanosecond extension in the SHM protocol
now enables sub-microsecond synchronization of the
system clock.

See also :

Solution :

Update the affected packages.

Risk factor :

Medium / CVSS Base Score : 5.0

Family: Scientific Linux Local Security Checks

Nessus Plugin ID: 85203 ()

Bugtraq ID:

CVE ID: CVE-2014-9297

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