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Debian Security Advisory DSA-3388-1                   security@debian.org
https://www.debian.org/security/                              Kurt Roeckx
November 01, 2015                     https://www.debian.org/security/faq
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Package        : ntp
CVE ID         : CVE-2014-9750 CVE-2014-9751 CVE-2015-3405 CVE-2015-5146 
                 CVE-2015-5194 CVE-2015-5195 CVE-2015-5219 CVE-2015-5300
                 CVE-2015-7691 CVE-2015-7692 CVE-2015-7701 CVE-2015-7702
                 CVE-2015-7703 CVE-2015-7704 CVE-2015-7850 CVE-2015-7852
                 CVE-2015-7855 CVE-2015-7871

Several vulnerabilities were discovered in the Network Time Protocol
daemon and utility programs:

CVE-2015-5146

   A flaw was found in the way ntpd processed certain remote
   configuration packets. An attacker could use a specially crafted
   package to cause ntpd to crash if:

   * ntpd enabled remote configuration
   * The attacker had the knowledge of the configuration password
   * The attacker had access to a computer entrusted to perform remote
     configuration

   Note that remote configuration is disabled by default in NTP.

CVE-2015-5194

    It was found that ntpd could crash due to an uninitialized
    variable when processing malformed logconfig configuration
    commands.

CVE-2015-5195

    It was found that ntpd exits with a segmentation fault when a
    statistics type that was not enabled during compilation (e.g.
    timingstats) is referenced by the statistics or filegen
    configuration command

CVE-2015-5219

    It was discovered that sntp program would hang in an infinite loop
    when a crafted NTP packet was received, related to the conversion
    of the precision value in the packet to double.

CVE-2015-5300

    It was found that ntpd did not correctly implement the -g option:

    Normally, ntpd exits with a message to the system log if the offset
    exceeds the panic threshold, which is 1000 s by default. This
    option allows the time to be set to any value without restriction;
    however, this can happen only once. If the threshold is exceeded
    after that, ntpd will exit with a message to the system log. This
    option can be used with the -q and -x options.

    ntpd could actually step the clock multiple times by more than the
    panic threshold if its clock discipline doesn't have enough time to
    reach the sync state and stay there for at least one update. If a
    man-in-the-middle attacker can control the NTP traffic since ntpd
    was started (or maybe up to 15-30 minutes after that), they can
    prevent the client from reaching the sync state and force it to step
    its clock by any amount any number of times, which can be used by
    attackers to expire certificates, etc.

    This is contrary to what the documentation says. Normally, the
    assumption is that an MITM attacker can step the clock more than the
    panic threshold only once when ntpd starts and to make a larger
    adjustment the attacker has to divide it into multiple smaller
    steps, each taking 15 minutes, which is slow.

CVE-2015-7691, CVE-2015-7692, CVE-2015-7702

    It was found that the fix for CVE-2014-9750 was incomplete: three
    issues were found in the value length checks in ntp_crypto.c, where
    a packet with particular autokey operations that contained malicious
    data was not always being completely validated. Receipt of these
    packets can cause ntpd to crash.

CVE-2015-7701

    A memory leak flaw was found in ntpd's CRYPTO_ASSOC. If ntpd is
    configured to use autokey authentication, an attacker could send
    packets to ntpd that would, after several days of ongoing attack,
    cause it to run out of memory.

CVE-2015-7703

    Miroslav Lichvar of Red Hat found that the :config command can be
    used to set the pidfile and driftfile paths without any
    restrictions. A remote attacker could use this flaw to overwrite a
    file on the file system with a file containing the pid of the ntpd
    process (immediately) or the current estimated drift of the system
    clock (in hourly intervals). For example:

    ntpq -c ':config pidfile /tmp/ntp.pid'
    ntpq -c ':config driftfile /tmp/ntp.drift'

    In Debian ntpd is configured to drop root privileges, which limits
    the impact of this issue.

CVE-2015-7704

    If ntpd as an NTP client receives a Kiss-of-Death (KoD) packet
    from the server to reduce its polling rate, it doesn't check if the
    originate timestamp in the reply matches the transmit timestamp from
    its request. An off-path attacker can send a crafted KoD packet to
    the client, which will increase the client's polling interval to a
    large value and effectively disable synchronization with the server.

CVE-2015-7850

    An exploitable denial of service vulnerability exists in the remote
    configuration functionality of the Network Time Protocol. A
    specially crafted configuration file could cause an endless loop
    resulting in a denial of service.  An attacker could provide a the
    malicious configuration file to trigger this vulnerability.

CVE-2015-7852

    A potential off by one vulnerability exists in the cookedprint
    functionality of ntpq. A specially crafted buffer could cause a
    buffer overflow potentially resulting in null byte being written out
    of bounds.

CVE-2015-7855

    It was found that NTP's decodenetnum() would abort with an assertion
    failure when processing a mode 6 or mode 7 packet containing an
    unusually long data value where a network address was expected. This
    could allow an authenticated attacker to crash ntpd.

CVE-2015-7871

    An error handling logic error exists within ntpd that manifests due
    to improper error condition handling associated with certain
    crypto-NAK packets. An unauthenticated, off-path attacker can force
    ntpd processes on targeted servers to peer with time sources of the
    attacker's choosing by transmitting symmetric active crypto-NAK
    packets to ntpd. This attack bypasses the authentication typically
    required to establish a peer association and allows an attacker to
    make arbitrary changes to system time.

For the oldstable distribution (wheezy), these problems have been fixed
in version 1:4.2.6.p5+dfsg-2+deb7u6.

For the stable distribution (jessie), these problems have been fixed in
version 1:4.2.6.p5+dfsg-7+deb8u1.

For the testing distribution (stretch), these problems have been fixed
in version 1:4.2.8p4+dfsg-3.

For the unstable distribution (sid), these problems have been fixed in
version 1:4.2.8p4+dfsg-3.

We recommend that you upgrade your ntp packages.

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://www.debian.org/security/

Mailing list: debian-security-announce@lists.debian.org
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