Debian DLA-2871-1 : lxml - LTS security update

#%NASL_MIN_LEVEL 70300
#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Debian Security Advisory dla-2871. The text
# itself is copyright (C) Software in the Public Interest, Inc.
#

include('deprecated_nasl_level.inc');
include('compat.inc');

if (description)
{
  script_id(156417);
  script_version("1.2");
  script_set_attribute(attribute:"plugin_modification_date", value:"2021/12/30");

  script_cve_id("CVE-2021-43818");

  script_name(english:"Debian DLA-2871-1 : lxml - LTS security update");

  script_set_attribute(attribute:"synopsis", value:
"The remote Debian host is missing a security-related update.");
  script_set_attribute(attribute:"description", value:
"The remote Debian 9 host has packages installed that are affected by a vulnerability as referenced in the dla-2871
advisory.

  - lxml is a library for processing XML and HTML in the Python language. Prior to version 4.6.5, the HTML
    Cleaner in lxml.html lets certain crafted script content pass through, as well as script content in SVG
    files embedded using data URIs. Users that employ the HTML cleaner in a security relevant context should
    upgrade to lxml 4.6.5 to receive a patch. There are no known workarounds available. (CVE-2021-43818)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version
number.");
  script_set_attribute(attribute:"see_also", value:"https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1001885");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/source-package/lxml");
  script_set_attribute(attribute:"see_also", value:"https://www.debian.org/lts/security/2021/dla-2871");
  script_set_attribute(attribute:"see_also", value:"https://security-tracker.debian.org/tracker/CVE-2021-43818");
  script_set_attribute(attribute:"see_also", value:"https://packages.debian.org/source/stretch/lxml");
  script_set_attribute(attribute:"solution", value:
"Upgrade the lxml packages.

For Debian 9 stretch, this problem has been fixed in version 3.7.1-1+deb9u5.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:N/C:P/I:P/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:R/S:C/C:L/I:L/A:L");
  script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C");
  script_set_attribute(attribute:"cvss_score_source", value:"CVE-2021-43818");

  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:"2021/12/13");
  script_set_attribute(attribute:"patch_publication_date", value:"2021/12/30");
  script_set_attribute(attribute:"plugin_publication_date", value:"2021/12/30");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:python-lxml");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:python-lxml-dbg");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:python-lxml-doc");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:python3-lxml");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:debian:debian_linux:python3-lxml-dbg");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:debian:debian_linux:9.0");
  script_end_attributes();

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

  script_copyright(english:"This script is Copyright (C) 2021 and is owned by Tenable, Inc. or an Affiliate thereof.");

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

  exit(0);
}

include('audit.inc');
include('debian_package.inc');

if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED);
if (!get_kb_item("Host/Debian/dpkg-l")) audit(AUDIT_PACKAGE_LIST_MISSING);

var release = get_kb_item('Host/Debian/release');
if ( isnull(release) ) audit(AUDIT_OS_NOT, 'Debian');
var release = chomp(release);
if (! preg(pattern:"^(9)\.[0-9]+", string:release)) audit(AUDIT_OS_NOT, 'Debian 9.0', 'Debian ' + release);
var cpu = get_kb_item('Host/cpu');
if (isnull(cpu)) audit(AUDIT_UNKNOWN_ARCH);
if ('x86_64' >!< cpu && cpu !~ "^i[3-6]86$" && 'aarch64' >!< cpu) audit(AUDIT_LOCAL_CHECKS_NOT_IMPLEMENTED, 'Debian', cpu);

var pkgs = [
    {'release': '9.0', 'prefix': 'python-lxml', 'reference': '3.7.1-1+deb9u5'},
    {'release': '9.0', 'prefix': 'python-lxml-dbg', 'reference': '3.7.1-1+deb9u5'},
    {'release': '9.0', 'prefix': 'python-lxml-doc', 'reference': '3.7.1-1+deb9u5'},
    {'release': '9.0', 'prefix': 'python3-lxml', 'reference': '3.7.1-1+deb9u5'},
    {'release': '9.0', 'prefix': 'python3-lxml-dbg', 'reference': '3.7.1-1+deb9u5'}
];

var flag = 0;
foreach package_array ( pkgs ) {
  var release = NULL;
  var prefix = NULL;
  var reference = NULL;
  if (!empty_or_null(package_array['release'])) release = package_array['release'];
  if (!empty_or_null(package_array['prefix'])) prefix = package_array['prefix'];
  if (!empty_or_null(package_array['reference'])) reference = package_array['reference'];
  if (release && prefix && reference) {
    if (deb_check(release:release, prefix:prefix, reference:reference)) flag++;
  }
}

if (flag)
{
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    extra      : deb_report_get()
  );
  exit(0);
}
else
{
  var tested = deb_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'python-lxml / python-lxml-dbg / python-lxml-doc / python3-lxml / etc');
}