ntp - security update

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
    configurationNote 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
  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.