Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : Dungeon Crawl Stone Stoup vulnerability (USN-7969-1)

#%NASL_MIN_LEVEL 80900
##
# (C) Tenable, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-7969-1. The text
# itself is copyright (C) Canonical, Inc. See
# <https://ubuntu.com/security/notices>. Ubuntu(R) is a registered
# trademark of Canonical, Inc.
##

include('compat.inc');

if (description)
{
  script_id(294896);
  script_version("1.1");
  script_set_attribute(attribute:"plugin_modification_date", value:"2026/01/21");

  script_cve_id("CVE-2020-11722");
  script_xref(name:"USN", value:"7969-1");

  script_name(english:"Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : Dungeon Crawl Stone Stoup vulnerability (USN-7969-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing a security update.");
  script_set_attribute(attribute:"description", value:
"The remote Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS host has packages installed that are affected by a vulnerability as
referenced in the USN-7969-1 advisory.

    David Mendenhall discovered that Dungeon Crawl Stone Soup was incorrectly handling Lua bytecode embedded
    in an uploaded .crawlrc file. An attacker could possibly use this issue to execute arbitrary code.

Tenable has extracted the preceding description block directly from the Ubuntu security advisory.

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://ubuntu.com/security/notices/USN-7969-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:N/AC:L/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:N/S:U/C:H/I:H/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-2020-11722");

  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:"2020/04/12");
  script_set_attribute(attribute:"patch_publication_date", value:"2026/01/19");
  script_set_attribute(attribute:"plugin_publication_date", value:"2026/01/21");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"cpe:/o:canonical:ubuntu_linux:16.04:-:lts");
  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:crawl");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:crawl-common");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:crawl-tiles");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:crawl-tiles-data");
  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) 2026 Canonical, Inc. / NASL script (C) 2026 and is owned by Tenable, Inc. or an Affiliate thereof.");

  script_dependencies("ssh_get_info.nasl", "ubuntu_pro_sub_detect.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 (! ('16.04' >< os_release || '18.04' >< os_release || '20.04' >< os_release)) audit(AUDIT_OS_NOT, 'Ubuntu 16.04 / 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 ubuntu_pro_detected = get_kb_item('Host/Ubuntu/Pro/Services/esm-apps');
ubuntu_pro_detected = !empty_or_null(ubuntu_pro_detected);

var pro_caveat_needed = FALSE;

var pkgs = [
    {'osver': '16.04', 'pkgname': 'crawl', 'pkgver': '2:0.17.1-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE},
    {'osver': '16.04', 'pkgname': 'crawl-common', 'pkgver': '2:0.17.1-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE},
    {'osver': '16.04', 'pkgname': 'crawl-tiles', 'pkgver': '2:0.17.1-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE},
    {'osver': '16.04', 'pkgname': 'crawl-tiles-data', 'pkgver': '2:0.17.1-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE},
    {'osver': '18.04', 'pkgname': 'crawl', 'pkgver': '2:0.21.1-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE},
    {'osver': '18.04', 'pkgname': 'crawl-common', 'pkgver': '2:0.21.1-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE},
    {'osver': '18.04', 'pkgname': 'crawl-tiles', 'pkgver': '2:0.21.1-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE},
    {'osver': '18.04', 'pkgname': 'crawl-tiles-data', 'pkgver': '2:0.21.1-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'crawl', 'pkgver': '2:0.24.0-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'crawl-common', 'pkgver': '2:0.24.0-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'crawl-tiles', 'pkgver': '2:0.24.0-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE},
    {'osver': '20.04', 'pkgname': 'crawl-tiles-data', 'pkgver': '2:0.24.0-1ubuntu0.1~esm1', 'ubuntu_pro': TRUE}
];

var flag = 0;
foreach var 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 (!empty_or_null(package_array['cves'])) cves = package_array['cves'];
  var pro_required = NULL;
  if (!empty_or_null(package_array['ubuntu_pro'])) pro_required = package_array['ubuntu_pro'];
  if (osver && pkgname && pkgver) {
    if (deb_check(release:osver, prefix:pkgname, reference:pkgver, cves:cves)) {
        flag++;
        if (!ubuntu_pro_detected && !pro_caveat_needed) pro_caveat_needed = pro_required;
    }
  }
}

if (flag)
{
  var extra = '';
  if (pro_caveat_needed) {
    extra += 'NOTE: This vulnerability check contains fixes that apply to packages only \n';
    extra += 'available in Ubuntu ESM repositories. Access to these package security updates \n';
    extra += 'require an Ubuntu Pro subscription.\n\n';
  }
  extra += ubuntu_report_get();
  security_report_v4(
    port       : 0,
    severity   : SECURITY_HOLE,
    extra      : extra
  );
  exit(0);
}
else
{
  var tested = ubuntu_pkg_tests_get();
  if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested);
  else audit(AUDIT_PACKAGE_NOT_INSTALLED, 'crawl / crawl-common / crawl-tiles / crawl-tiles-data');
}