Amazon Linux AMI : nginx (ALAS-2016-655)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Amazon Linux AMI Security Advisory ALAS-2016-655.
#

include("compat.inc");

if (description)
{
  script_id(89120);
  script_version("2.4");
  script_cvs_date("Date: 2018/04/18 15:09:35");

  script_cve_id("CVE-2016-0742", "CVE-2016-0746", "CVE-2016-0747");
  script_xref(name:"ALAS", value:"2016-655");

  script_name(english:"Amazon Linux AMI : nginx (ALAS-2016-655)");
  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 nginx could perform an out of bound read and
dereference an invalid pointer when resolving CNAME DNS records. An
attacker able to manipulate DNS responses received by nginx could use
this flaw to cause a worker process to crash if nginx enabled the
resolver in its configuration. (CVE-2016-0742)

A use-after-free flaw was found in the way nginx resolved certain
CNAME DNS records. An attacker able to manipulate DNS responses
received by nginx could use this flaw to cause a worker process to
crash or, possibly, execute arbitrary code if nginx enabled the
resolver in its configuration. (CVE-2016-0746)

It was discovered that nginx did not limit recursion when resolving
CNAME DNS records. An attacker able to manipulate DNS responses
received by nginx could use this flaw to cause a worker process to use
an excessive amount of resources if nginx enabled the resolver in its
configuration. (CVE-2016-0747)"
  );
  script_set_attribute(
    attribute:"see_also",
    value:"https://alas.aws.amazon.com/ALAS-2016-655.html"
  );
  script_set_attribute(
    attribute:"solution", 
    value:"Run 'yum update nginx' to update your system."
  );
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P");
  script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L");

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

  script_set_attribute(attribute:"patch_publication_date", value:"2016/02/19");
  script_set_attribute(attribute:"plugin_publication_date", value:"2016/03/04");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_copyright(english:"This script is Copyright (C) 2016-2018 Tenable Network Security, Inc.");
  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:"nginx-1.8.1-1.26.amzn1")) flag++;
if (rpm_check(release:"ALA", reference:"nginx-debuginfo-1.8.1-1.26.amzn1")) flag++;

if (flag)
{
  if (report_verbosity > 0) security_hole(port:0, extra:rpm_report_get());
  else security_hole(0);
  exit(0);
}
else
{
  tested = pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, "nginx / nginx-debuginfo");
}