Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : snapd vulnerabilities (USN-4424-1)

#
# (C) Tenable Network Security, Inc.
#
# The descriptive text and package checks in this plugin were
# extracted from Ubuntu Security Notice USN-4424-1. 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(138552);
  script_version("1.7");
  script_set_attribute(attribute:"plugin_modification_date", value:"2024/08/27");

  script_cve_id("CVE-2020-11933", "CVE-2020-11934");
  script_xref(name:"USN", value:"4424-1");

  script_name(english:"Ubuntu 16.04 LTS / 18.04 LTS / 20.04 LTS : snapd vulnerabilities (USN-4424-1)");

  script_set_attribute(attribute:"synopsis", value:
"The remote Ubuntu host is missing one or more security updates.");
  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 multiple
vulnerabilities as referenced in the USN-4424-1 advisory.

    It was discovered that cloud-init as managed by snapd on Ubuntu Core 16 and Ubuntu Core 18 devices ran on
    every boot without restrictions. A physical attacker could exploit this to craft cloud-init user-
    data/meta-data via external media to perform arbitrary changes on the device to bypass intended security
    mechanisms such as full disk encryption. This issue did not affect traditional Ubuntu systems.
    (CVE-2020-11933)

    It was discovered that snapctl user-open allowed altering the XDG_DATA_DIRS

    environment variable when calling the system xdg-open. A malicious snap

    could exploit this to bypass intended access restrictions to control how the host system xdg-open script
    opens the URL. This issue did not affect

    Ubuntu Core systems. (CVE-2020-11934)

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

Note that Nessus has not tested for these issues 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-4424-1");
  script_set_attribute(attribute:"solution", value:
"Update the affected packages.");
  script_set_cvss_base_vector("CVSS2#AV:L/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:P/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-2020-11933");

  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:"2020/07/29");
  script_set_attribute(attribute:"patch_publication_date", value:"2020/07/15");
  script_set_attribute(attribute:"plugin_publication_date", value:"2020/07/16");

  script_set_attribute(attribute:"plugin_type", value:"local");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:snapd");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:snapd-xdg-open");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:ubuntu-core-launcher");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:ubuntu-core-snapd-units");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:ubuntu-snappy");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:ubuntu-snappy-cli");
  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:golang-github-snapcore-snapd-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:golang-github-ubuntu-core-snappy-dev");
  script_set_attribute(attribute:"cpe", value:"p-cpe:/a:canonical:ubuntu_linux:snap-confine");
  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) 2020-2024 Canonical, Inc. / NASL script (C) 2020-2024 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 (! ('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 pkgs = [
    {'osver': '16.04', 'pkgname': 'golang-github-snapcore-snapd-dev', 'pkgver': '2.45.1ubuntu0.2'},
    {'osver': '16.04', 'pkgname': 'golang-github-ubuntu-core-snappy-dev', 'pkgver': '2.45.1ubuntu0.2'},
    {'osver': '16.04', 'pkgname': 'snap-confine', 'pkgver': '2.45.1ubuntu0.2'},
    {'osver': '16.04', 'pkgname': 'snapd', 'pkgver': '2.45.1ubuntu0.2'},
    {'osver': '16.04', 'pkgname': 'snapd-xdg-open', 'pkgver': '2.45.1ubuntu0.2'},
    {'osver': '16.04', 'pkgname': 'ubuntu-core-launcher', 'pkgver': '2.45.1ubuntu0.2'},
    {'osver': '16.04', 'pkgname': 'ubuntu-core-snapd-units', 'pkgver': '2.45.1ubuntu0.2'},
    {'osver': '16.04', 'pkgname': 'ubuntu-snappy', 'pkgver': '2.45.1ubuntu0.2'},
    {'osver': '16.04', 'pkgname': 'ubuntu-snappy-cli', 'pkgver': '2.45.1ubuntu0.2'},
    {'osver': '18.04', 'pkgname': 'golang-github-snapcore-snapd-dev', 'pkgver': '2.45.1+18.04.2'},
    {'osver': '18.04', 'pkgname': 'golang-github-ubuntu-core-snappy-dev', 'pkgver': '2.45.1+18.04.2'},
    {'osver': '18.04', 'pkgname': 'snap-confine', 'pkgver': '2.45.1+18.04.2'},
    {'osver': '18.04', 'pkgname': 'snapd', 'pkgver': '2.45.1+18.04.2'},
    {'osver': '18.04', 'pkgname': 'snapd-xdg-open', 'pkgver': '2.45.1+18.04.2'},
    {'osver': '18.04', 'pkgname': 'ubuntu-core-launcher', 'pkgver': '2.45.1+18.04.2'},
    {'osver': '18.04', 'pkgname': 'ubuntu-core-snapd-units', 'pkgver': '2.45.1+18.04.2'},
    {'osver': '18.04', 'pkgname': 'ubuntu-snappy', 'pkgver': '2.45.1+18.04.2'},
    {'osver': '18.04', 'pkgname': 'ubuntu-snappy-cli', 'pkgver': '2.45.1+18.04.2'},
    {'osver': '20.04', 'pkgname': 'golang-github-snapcore-snapd-dev', 'pkgver': '2.45.1+20.04.2'},
    {'osver': '20.04', 'pkgname': 'golang-github-ubuntu-core-snappy-dev', 'pkgver': '2.45.1+20.04.2'},
    {'osver': '20.04', 'pkgname': 'snap-confine', 'pkgver': '2.45.1+20.04.2'},
    {'osver': '20.04', 'pkgname': 'snapd', 'pkgver': '2.45.1+20.04.2'},
    {'osver': '20.04', 'pkgname': 'snapd-xdg-open', 'pkgver': '2.45.1+20.04.2'},
    {'osver': '20.04', 'pkgname': 'ubuntu-core-launcher', 'pkgver': '2.45.1+20.04.2'},
    {'osver': '20.04', 'pkgname': 'ubuntu-core-snapd-units', 'pkgver': '2.45.1+20.04.2'},
    {'osver': '20.04', 'pkgname': 'ubuntu-snappy', 'pkgver': '2.45.1+20.04.2'},
    {'osver': '20.04', 'pkgname': 'ubuntu-snappy-cli', 'pkgver': '2.45.1+20.04.2'}
];

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 (osver && pkgname && pkgver) {
    if (ubuntu_check(osver:osver, pkgname:pkgname, pkgver:pkgver)) flag++;
  }
}

if (flag)
{
  var extra = '';
  extra += ubuntu_report_get();
  security_report_v4(
    port       : 0,
    severity   : SECURITY_WARNING,
    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, 'golang-github-snapcore-snapd-dev / etc');
}