The remote Redhat Enterprise Linux 6 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2015:1459 advisory.

    The Network Time Protocol (NTP) is used to synchronize a computer's time     with another referenced time source.

    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)

    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)

    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. (CVE-2015-1798)

    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. (BZ#1053551)

    * 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. (BZ#1184421)

    * 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. (BZ#1045376)

    * 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. (BZ#1171630)

    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. (BZ#1122015)

    * 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.
    (BZ#1117704)

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

Detections

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RHEL 6 : ntp (RHSA-2015:1459)

high Nessus Plugin ID 84951

Version 2.26