Amazon Linux AMI : ntp (ALAS-2016-727)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux AMI Security Advisory ALAS-2016-727.
#

include("compat.inc");

if (description)
{
  script_id(92662);
  script_version("2.9");
  script_set_attribute(attribute:"plugin_modification_date", value:"2020/06/22");

  script_cve_id("CVE-2015-8139", "CVE-2016-4954", "CVE-2016-4955", "CVE-2016-4956");
  script_xref(name:"ALAS", value:"2016-727");

  script_name(english:"Amazon Linux AMI : ntp (ALAS-2016-727)");
  script_summary(english:"Checks rpm output for the updated packages");

  script_set_attribute(
    attribute:"synopsis",
    value:"The remote Amazon Linux AMI host is missing a security update."
  );
  script_set_attribute(
    attribute:"description",
    value:
"It was discovered that ntpq and ntpdc disclosed the origin timestamp
to unauthenticated clients, which could permit such clients to forge
the server's replies. (CVE-2015-8139)

The process_packet function in ntp_proto.c in ntpd in NTP 4.x before
4.2.8p8 allows remote attackers to cause a denial of service
(peer-variable modification) by sending spoofed packets from many
source IP addresses in a certain scenario, as demonstrated by
triggering an incorrect leap indication. (CVE-2016-4954)

ntpd in NTP 4.x before 4.2.8p8, when autokey is enabled, allows remote
attackers to cause a denial of service (peer-variable clearing and
association outage) by sending (1) a spoofed crypto-NAK packet or (2)
a packet with an incorrect MAC value at a certain time.
(CVE-2016-4955)

ntpd in NTP 4.x before 4.2.8p8 allows remote attackers to cause a
denial of service (interleaved-mode transition and time change) via a
spoofed broadcast packet. This vulnerability exists because of an
incomplete fix for CVE-2016-1548 . (CVE-2016-4956)"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://alas.aws.amazon.com/ALAS-2016-727.html"
  );
  script_set_attribute(
    attribute:"solution",
    value:"Run 'yum update ntp' to update your system."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:ntp");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:ntp-debuginfo");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:ntp-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:ntp-perl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:amazon:linux:ntpdate");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:amazon:linux");

  script_set_attribute(attribute:"vuln_publication_date", value:"2016/07/05");
  script_set_attribute(attribute:"patch_publication_date", value:"2017/01/04");
  script_set_attribute(attribute:"plugin_publication_date", value:"2016/08/02");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2016-2020 and is owned by Tenable, Inc. or an Affiliate thereof.");
  script_family(english:"Amazon Linux Local Security Checks");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/local_checks_enabled", "Host/AmazonLinux/release", "Host/AmazonLinux/rpm-list");

  exit(0);
}


include("audit.inc");
include("global_settings.inc");
include("rpm.inc");


if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);

release = get_kb_item("Host/AmazonLinux/release");
if (isnull(release) || !strlen(release)) audit(AUDIT_OS_NOT, "Amazon Linux");
os_ver = pregmatch(pattern: "^AL(A|\d)", string:release);
if (isnull(os_ver)) audit(AUDIT_UNKNOWN_APP_VER, "Amazon Linux");
os_ver = os_ver[1];
if (os_ver != "A")
{
  if (os_ver == 'A') os_ver = 'AMI';
  audit(AUDIT_OS_NOT, "Amazon Linux AMI", "Amazon Linux " + os_ver);
}

if (!get_kb_item("Host/AmazonLinux/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING);


flag = 0;
if (rpm_check(release:"ALA", reference:"ntp-4.2.6p5-41.32.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"ntp-debuginfo-4.2.6p5-41.32.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"ntp-doc-4.2.6p5-41.32.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"ntp-perl-4.2.6p5-41.32.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"ntpdate-4.2.6p5-41.32.amzn1")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_warning(port:0, extra:rpm_report_get());
  else security_warning(0);
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "ntp / ntp-debuginfo / ntp-doc / ntp-perl / ntpdate");
}