Ubuntu 18.04 LTS / 20.04 LTS : Unbound vulnerabilities (USN-4374-1)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4374-1. The text 
# itself is copyright (C) Canonical, Inc. See 
# <http://www.ubuntu.com/usn/>. Ubuntu(R) is a registered 
# trademark of Canonical, Inc.
#

include('compat.inc');

if (description)
{
  script_id(136943);
  script_version("1.6");
  script_set_attribute(attribute:"plugin_modification_date", value:"2023/10/20");

  script_cve_id("CVE-2020-12662", "CVE-2020-12663");
  script_xref(name:"USN", value:"4374-1");

  script_name(english:"Ubuntu 18.04 LTS / 20.04 LTS : Unbound vulnerabilities (USN-4374-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  script_set_attribute(attribute:"description", value:
"Lior Shafir, Yehuda Afek, and Anat Bremler-Barr discovered that
Unbound incorrectly handled certain queries. A remote attacker could
use this issue to perform an amplification attack directed at a
target. (CVE-2020-12662)

It was discovered that Unbound incorrectly handled certain malformed
answers. A remote attacker could possibly use this issue to cause
Unbound to crash, resulting in a denial of service. (CVE-2020-12663).

Note that Tenable Network Security has extracted the preceding
description block directly from the Ubuntu security advisory. Tenable
has attempted to automatically clean and format it as much as possible
without introducing additional issues.");
  script_set_attribute(attribute:"see_also", value:"https://ubuntu.com/security/notices/USN-4374-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P");
  script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C");
  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_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2020-12663");

  script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"false");

  script_set_attribute(attribute:"vuln_publication_date", value:"2020/05/19");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/05/27");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/05/28");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libunbound2");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libunbound8");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python-unbound");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:python3-unbound");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:unbound");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:unbound-anchor");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:unbound-host");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:18.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:20.04:-:lts");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:libunbound-dev");
  script_set_attribute(attribute:"generated_plugin", value:"current");
  script_end_attributes();

  script_category(ACT_GATHER_INFO);
  script_family(english:"Ubuntu Local Security Checks");

  script_copyright(english:"Ubuntu Security Notice (C) 2020-2023 Canonical, Inc. / NASL script (C) 2020-2023 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl");
  script_require_keys("Host/cpu", "Host/Ubuntu", "Host/Ubuntu/release", "Host/Debian/dpkg-l");

  exit(0);
}

include('debian_package.inc');

if ( ! get_kb_item('Host/local_checks_enabled') ) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
var os_release = get_kb_item('Host/Ubuntu/release');
if ( isnull(os_release) ) audit(AUDIT_OS_NOT, 'Ubuntu');
os_release = chomp(os_release);
if (! ('18.04' >< os_release || '20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 18.04 / 20.04', 'Ubuntu ' + os_release);
if ( ! get_kb_item('Host/Debian/dpkg-l') ) audit(AUDIT_PACKAGE_LIST_MISSING);

var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 's390' >!< cpu && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Ubuntu', cpu);

var pkgs = [
    {'osver': '18.04', 'pkgname': 'libunbound-dev', 'pkgver': '1.6.7-1ubuntu2.3'},
    {'osver': '18.04', 'pkgname': 'libunbound2', 'pkgver': '1.6.7-1ubuntu2.3'},
    {'osver': '18.04', 'pkgname': 'python-unbound', 'pkgver': '1.6.7-1ubuntu2.3'},
    {'osver': '18.04', 'pkgname': 'python3-unbound', 'pkgver': '1.6.7-1ubuntu2.3'},
    {'osver': '18.04', 'pkgname': 'unbound', 'pkgver': '1.6.7-1ubuntu2.3'},
    {'osver': '18.04', 'pkgname': 'unbound-anchor', 'pkgver': '1.6.7-1ubuntu2.3'},
    {'osver': '18.04', 'pkgname': 'unbound-host', 'pkgver': '1.6.7-1ubuntu2.3'},
    {'osver': '20.04', 'pkgname': 'libunbound-dev', 'pkgver': '1.9.4-2ubuntu1.1'},
    {'osver': '20.04', 'pkgname': 'libunbound8', 'pkgver': '1.9.4-2ubuntu1.1'},
    {'osver': '20.04', 'pkgname': 'python-unbound', 'pkgver': '1.9.4-2ubuntu1.1'},
    {'osver': '20.04', 'pkgname': 'python3-unbound', 'pkgver': '1.9.4-2ubuntu1.1'},
    {'osver': '20.04', 'pkgname': 'unbound', 'pkgver': '1.9.4-2ubuntu1.1'},
    {'osver': '20.04', 'pkgname': 'unbound-anchor', 'pkgver': '1.9.4-2ubuntu1.1'},
    {'osver': '20.04', 'pkgname': 'unbound-host', 'pkgver': '1.9.4-2ubuntu1.1'}
];

var flag = 0;
foreach package_array ( pkgs ) {
  var osver = NULL;
  var pkgname = NULL;
  var pkgver = NULL;
  if (!empty_or_null(package_array['osver'])) osver = package_array['osver'];
  if (!empty_or_null(package_array['pkgname'])) pkgname = package_array['pkgname'];
  if (!empty_or_null(package_array['pkgver'])) pkgver = package_array['pkgver'];
  if (osver && pkgname && pkgver) {
    if (ubuntu_check(osver:osver, pkgname:pkgname, pkgver:pkgver)) flag++;
  }
}

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : ubuntu_report_get()
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'libunbound-dev / libunbound2 / libunbound8 / python-unbound / etc');
}